Biomedical subjects

M J Robertson

Publications and source records attributed to M J Robertson.

At least 73 records · Page 4Linked to original sources

PubMed1993

Interleukin-12 augments cytolytic activity of peripheral blood lymphocytes from patients with hematologic and solid malignancies.

Interleukin-12 (IL-12) is a heterodimeric 70-kD cytokine that can enhance the activity of cytotoxic effector cells. Although IL-12 shares some functional properties with interleukin-2 (IL-2), it appears to act via a distinct mechanism. In this report, we examined the effects of IL-12 on the cytolytic activity and proliferation of peripheral blood mononuclear cells (PBMC) obtained from patients with malignant disease. PBMC from two groups of patients were evaluated. The first group consisted of 12 individuals with metastatic solid tumors. PBMC from these patients demonstrated a marked defect in their ability to lyse natural killer (NK)-sensitive targets (K562) compared with normal volunteers. Overnight incubation with IL-12 (35 pmol/L) corrected this defect. The effect of 35 pmol/L of IL-12 on cytotoxicity was similar to that of 3 nmol/L of IL-2. In contrast, this concentration of IL-12 had little effect on cytolytic activity against an NK-resistant cell line (COLO 205). When IL-12 was added to PBMC obtained from cancer patients who were being treated with low-dose IL-2 in vivo, a dramatic increase in cytolytic activity against both NK-sensitive and -resistant tumor targets was observed. Unlike IL-2, IL-12 failed to stimulate proliferation of resting PBMC from cancer patients significantly. The second group of patients we studied comprised 13 patients who had recently undergone allogeneic bone marrow transplantation (BMT) for hematologic malignancy. In resting PBMC from these transplant recipients, IL-12 was capable of enhancing cytotoxicity against both NK-sensitive and -resistant tumor targets. Our findings indicate that IL-12 can restore defective NK activity of PBMC from patients with metastatic cancer, as well as enhance cytolytic function of PBMC from patients after allogeneic BMT. The clinical use of IL-12 as an immunomodulator in patients with malignancy merits further consideration.

Adult↗

PubMed1993

Monoclonal antibody-purged bone marrow transplantation therapy for multiple myeloma.

Forty patients with plasma cell dyscrasias underwent high-dose chemoradiotherapy and either anti-B-cell monoclonal antibody (MoAb)-treated autologous, anti-T-cell MoAb-treated HLA-matched sibling allogeneic or syngeneic bone marrow transplantation (BMT). The majority of patients had advanced Durie-Salmon stage myeloma at diagnosis, all were pretreated with chemotherapy, and 17 had received prior radiotherapy. At the time of BMT, all patients demonstrated good performance status with Karnofsky score of 80% or greater and had less than 10% marrow tumor cells; 34 patients had residual monoclonal marrow plasma cells and 38 patients had paraprotein. Following high-dose chemoradiotherapy, there were 18 complete responses (CR), 18 partial responses, one non-responder, and three toxic deaths. Granulocytes greater than 500/microL and untransfused platelets greater than 20,000/microL were noted at a median of 23 (range, 12 to 46) and 25 (range, 10 to 175) days posttransplant (PT), respectively, in 24 of the 26 patients who underwent autografting. In the 14 patients who received allogeneic or syngeneic grafts, granulocytes greater than 500/microL and untransfused platelets greater than 20,000/microL were noted at a median of 19 (range, 12 to 24) and 16 (range, 5 to 32) days PT, respectively. With 24 months median follow-up for survival after autologous BMT, 16 of 26 patients are alive free from progression at 2+ to 55+ months PT; of these, 5 patients remain in CR at 6+ to 55+ months PT. With 24 months median follow-up for survival after allogeneic and syngeneic BMT, 8 of 14 patients are alive free from progression at 8+ to 34+ months PT; of these, 5 patients remain in CR at 8+ to 34+ months PT. This therapy has achieved high response rates and prolonged progression-free survival in some patients and proven to have acceptable toxicity. However, relapses post-BMT, coupled with slow engraftment post-BMT in heavily pretreated patients, suggest that such treatment strategies should be used earlier in the disease course. To define the role of BMT in the treatment of myeloma, its efficacy should be compared with that of conventional chemotherapy in a randomized trial.

Adult↗

PubMed1993

Prediction of graft-versus-host disease by phenotypic analysis of early immune reconstitution after CD6-depleted allogeneic bone marrow transplantation.

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality following allogeneic bone marrow transplantation (BMT). Because GVHD is frequently refractory to treatment, the early identification of high-risk patients could have significant clinical value. To identify such patients, we examined early immunologic recovery in 136 patients with hematologic malignancies who received anti-T12 (CD6)-purged allogeneic bone marrow over a 9-year period. The majority of patients received marrow from HLA-matched sibling donors after ablation with cyclophosphamide and total body irradiation. No patients received any immune suppressive medications for GVHD prophylaxis. The fraction and absolute numbers of peripheral blood lymphocytes (PBL) expressing the CD3, CD4, CD8, and CD56 surface antigens were determined weekly by immunofluorescence analysis in patients beginning 8 to 14 days (week 2) after marrow infusion. Results in patients who did or did not subsequently develop GVHD post-BMT were compared. Within 2 weeks of marrow infusion, patients who developed grades 2-4 GVHD had significantly higher percentages and absolute numbers of CD8+ T cells and a lower fraction of CD56+ natural killer (NK) cells than individuals who remained free of GVHD. Thirty-five percent of patients whose PBL were greater than 25% CD8+ in the second posttransplant week developed GVHD, compared with only 3% of patients who had < or = 25% CD8+ cells (odds ratio 37.8; 95% confidence interval [CI] 4.1 to 397). A subgroup of patients at very high risk for GVHD could be identified based on the combined frequency of CD8+ T cells and NK cells in blood. Seventy-five percent of patients with greater than 25% CD8+ cells and < or = 45% CD56+ cells during week 2 post-BMT developed GVHD, compared with only 11% of the remaining patients (odds ratio 24.9; 95% CI, 5.3 to 117.0). None of the 23 patients with both less than 25% CD8+ cells and greater than 45% CD56+ cells in the second posttransplant week developed grades 2-4 GVHD. Our findings indicate that CD8+ T cells play an important role in the pathogenesis of GVHD in humans. Analysis of immune reconstitution early after BMT is useful in predicting the onset of GVHD and can help direct the implementation of treatment strategies before the appearance of clinical manifestations. Such interventions may decrease the morbidity and mortality associated with allogeneic BMT and ultimately improve overall survival.

Adult↗

PubMed1993

Costimulatory signals are required for optimal proliferation of human natural killer cells.

CD56dim NK cells, which comprise approximately 90% of human peripheral blood NK cells, respond to IL-2 with cytokine production, up-regulation of functionally relevant surface molecules, and augmented cytolytic activity. Nevertheless, CD56dim NK cells proliferate poorly in response to IL-2 alone. We found that other NK cell mitogens, including IL-4, IL-7, and IL-12, also induced little proliferation of CD56dim NK cells. Indeed, IL-2 stimulated at least 10-fold more NK cell proliferation than did IL-4, IL-7, or IL-12. In contrast, leukocyte-conditioned medium (LCM) induced two- to threefold greater proliferation of CD56dim NK cells than did optimal concentrations of IL-2. Although the calcium ionophore ionomycin did not stimulate proliferation by itself, it markedly augmented LCM-induced proliferation of CD56dim NK cells. Proliferation in response to either LCM alone or LCM together with ionomycin was almost completely abrogated by anti-IL-2R antibodies. Thus, IL-2 appears to be necessary but not sufficient for optimal proliferation of CD56dim NK cells. LCM-induced proliferation of ionomycin-activated CD56dim NK cells was inhibited 24% by anti-IL-1 heteroantisera and 57% by anti-TNF antisera; a combination of both antisera inhibited proliferation by 73%. Furthermore, although rIL-1 and TNF did not induce proliferation by themselves, both cytokines could augment IL-2-induced proliferation of resting or ionomycin-activated NK cells. Hence IL-1 and TNF do not appear to be primary NK cell mitogens, but rather accessory factors that can enhance IL-2-dependent NK cell proliferation. Stimulation through CD2 or CD16 Ag did not enhance LCM-induced NK cell proliferation. However, stimulation with NK-sensitive K562 cells strongly augmented CD56dim NK cell proliferation to LCM or to IL-2, IL-1, and TNF in combination. NK-resistant Daudi cells did not promote the proliferation of highly purified NK cells. Thus, NK cell proliferation may be enhanced by triggering through putative receptors for natural killing, and ionomycin may mimic such triggering. Although IL-2 by itself can induce NK cell proliferation, most NK cells resemble T and B lymphocytes in that they require multiple signals for optimal proliferation.

Animals↗

PubMed1993

Hematologic remission and cytogenetic improvement after treatment of stable-phase chronic myelogenous leukemia with continuous infusion of low-dose cytarabine.

Prolonged exposure to low concentrations of cytarabine preferentially inhibits in vitro growth of neoplastic myeloid progenitors from patients with chronic myelogenous leukemia (CML) compared to that of normal myeloid progenitors. Continuous infusions of cytarabine in doses of 15-30 mg/m2/day were therefore administered for extended periods to patients with CML in stable phase to determine if this treatment could achieve selective cytoreduction of Philadelphia chromosome (Ph)-positive cells. Five patients demonstrating > 90% Ph-positive metaphases before treatment received a total of 43 cycles of cytarabine infusional therapy. Cytarabine was administered on an outpatient basis using a portable, battery-operated syringe pump until the total leukocyte count reached 2500/microliters or the platelet count reached 75,000/microliters. A new cycle was begun when the total leukocyte count exceeded 4,000/microliters and the platelet count exceeded 100,000/microliters. The median duration of cytarabine administration per cycle was 29 days (range 15-72 days). Leukocytosis was readily controlled by low-dose cytarabine therapy in all patients. All five patients experienced complete hematologic responses during cytarabine therapy. The fraction of Ph-positive metaphases in the marrow of the five patients was reduced to 0, 10%, 43%, 72%, and 84%, respectively, during therapy. The median time to achieve optimal cytogenetic response was 4.8 months (range 2.8-8.6 months). One patient demonstrated a complete cytogenetic response after three cycles of cytarabine. Another patient demonstrated persistent cytogenetic improvement during 20 cycles of cytarabine, with a median 38% Ph-positive marrow metaphases (range 10-53%) over 32 months. Cytarabine therapy was generally well-tolerated, but was discontinued in one patient because of persistent asymptomatic elevations in hepatic enzymes, which resolved within 2 months after discontinuing therapy. There were no episodes of fever during neutropenia, and platelet transfusions were not required. However, symptomatic anemia requiring transfusion of red cells occurred during most cycles of treatment. In summary, treatment of CML with low-dose cytarabine can induce prolonged cytogenetic improvement in some patients with acceptable toxicity. Further evaluation is needed to ascertain the effect of this treatment on duration of stable phase and overall survival.

Adult↗

PubMed1993

Role of angiotensin AT1 and AT2 receptors in mediating the renal effects of angiotensin II in the anaesthetized dog.

1. Experiments were performed using the selective AT1 receptor antagonist, GR117289, and the selective AT2 receptor antagonist, PD123177, to assess the relative importance of AT1 versus AT2 receptors in mediating the renal effects of angiotensin II (AII) in vivo, in salt-replete pentobarbitone-anaesthetized dogs. 2. The AT1 receptor antagonist, GR117289 (0.5 mg kg-1 + 1 microgram kg-1 min-1, i.v.), caused renal vasodilatation, characterized by a mean increase of 21 +/- 5% in renal blood flow, 45 min post-dose. GR117289 also caused a fall in mean blood pressure (12 +/- 4%), but despite this, sodium and urine excretion were not reduced. Indeed, there was a tendency for urine output and sodium excretion to increase, although the changes were not statistically significant. GR117289 caused a reduction in plasma aldosterone levels (-35 +/- 16%) 45 min post-dose, despite increasing plasma renin activity (+ 173 +/- 42%). In contrast to GR117289, the AT2 receptor antagonist, PD123177 (20 micrograms kg-1 min-1 intra-renal artery; i.r.a.) caused no significant change in blood pressure, renal blood flow, or sodium and urine excretion, indicating that the renal effects of endogenous AII in these salt-replete animals are mediated predominantly by AT1 receptors. 3. Intra-renal artery infusion of AII (1-300 ng kg-1 min-1) caused dose-related renal vasoconstriction, and decreases in urine output, sodium excretion, fractional excretion of sodium, and glomerular filtration rate (GFR). The AT1 receptor antagonist, GRI 17289 (0.5 mg kg-1 + 1 microg kg-1 min-1, i.v.)antagonized these renal effects of AII, causing 15-38 fold rightward displacements of mean dose response curves for these parameters. In contrast, PD123177 (20 microg kg-1 min-1, i.r.a.) failed to antagonize the renal haemodynamic and excretory effects of lower doses of All (1-10 ng kg-1 min-1,i.r.a.). However, at higher doses of AII (30-300 ng kg-l min-1, i.r.a.), while PD123177 still failed to antagonize the effects of the peptide on urine output, sodium excretion and GFR, it did cause a small,but significant, degree of inhibition of All-induced renal vasoconstriction. In addition, at a higher dose(50 microg kg-1 min-1, i.r.a.), PD123177 caused a greater degree of antagonism of AII-induced renal vasoconstriction, while renal excretory responses to AII remained unaffected.4. This study shows that the renal haemodynamic and excretory effects of AII in salt-replete anaesthetized dogs are mainly mediated by angiotensin AT1 receptors. However, the inhibitory effect of PD123177 on renal vasoconstrictor responses to high doses of AII, raises the possibility that functionally important AT2 receptors are present in the canine renal vasculature.

Anesthesia↗

PubMed1993

Selective modulation of human natural killer cells in vivo after prolonged infusion of low dose recombinant interleukin 2.

The immunologic consequences of prolonged infusions of rIL-2 in doses that produce physiologic serum concentrations of this cytokine were investigated. rIL-2 in doses of 0.5-6.0 x 10(6) U/m2 per d (3.3-40 micrograms/m2 per d) was administered by continuous intravenous infusion for 90 consecutive days to patients with advanced cancer. IL-2 concentrations (25 +/- 25 and 77 +/- 64 pM, respectively) that selectively saturate high-affinity IL-2 receptors (IL-2R) were achieved in the serum of patients receiving rIL-2 infusions of 10 micrograms/m2 per d and 30 micrograms/m2 per d. A gradual, progressive expansion of natural killer (NK) cells was seen in the peripheral blood of these patients with no evidence of a plateau effect during the 3 mo of therapy. A preferential expansion of CD56bright NK cells was consistently evident. NK cytotoxicity against tumor targets was only slightly enhanced at these dose levels. However, brief incubation of these expanded NK cells with IL-2 in vitro induced potent lysis of NK-sensitive, NK-resistant, and antibody-coated targets. Infusions of rIL-2 at 40 micrograms/m2 per d produced serum IL-2 levels (345 +/- 381 pM) sufficient to engage intermediate affinity IL-2R p75, which is constitutively expressed by human NK cells. This did not result in greater NK cell expansion compared to the lower dose levels, but did produce in vivo activation of NK cytotoxicity, as evidenced by lysis of NK-resistant targets. There was no consistent change in the numbers of CD56- CD3+ T cells, CD56+ CD3+ MHC-unrestricted T cells, or B cells during infusions of rIL-2 at any of the dosages used. This study demonstrates that prolonged infusions of rIL-2 in doses that saturate only high affinity IL-2R can selectively expand human NK cells for an extended period of time with only minimal toxicity. Further activation of NK cytolytic activity can also be achieved in vivo, but it requires concentrations of IL-2 that bind intermediate affinity IL-2R p75. Clinical trials are underway attempting to exploit the differing effects of various concentrations of IL-2 on human NK cells in vivo.

Antibody-Dependent Cell Cytotoxicity↗

PubMed1993

Life-styles, adaptive strategies, and sexual behaviors of homeless adolescents.

OBJECTIVES: The purpose of this study was to gather information about homeless adolescents, a largely invisible and understudied population. METHODS: Highly trained interviewers conducted structured face-to-face field interviews with 93 homeless adolescents between the ages of 13 and 17 in the Hollywood area of Los Angeles. RESULTS: Seventy-nine percent of the sample had experienced more than one homeless episode in their lifetime, and almost a fourth reported more than ten episodes. Mean length of time homeless was 440 days (median of 201 days). Aggressive and violent behaviors, including stealing, destruction of property, and physical fights, were common. The sample had a high prevalence of several mental disorders, including conduct disorder with aggression, major depression, and alcohol and drug abuse. Almost half had attempted suicide. Nearly all the adolescents were sexually active; about a third had more than ten partners in the previous year. About a third reported trading sex for money, food, or drugs. Although most had basic knowledge of HIV transmission and used some form of birth control, little more than half had used a condom in the most recent sexual encounter, and 18 percent reported sex with intravenous drug users. CONCLUSIONS: Further research on this population is needed, and follow-up contacts in particular are essential in developing appropriate and successful service programs for them.

Adaptation, Psychological↗

PubMed1993

Autologous bone marrow transplantation in poor-prognosis intermediate-grade and high-grade B-cell non-Hodgkin's lymphoma in first remission: a pilot study.

PURPOSE: Using high-dose therapy and autologous bone marrow transplantation (ABMT) to overcome cellular resistance and eradicate minimal disease, we initiated a pilot study during first remission in patients with non-Hodgkin's lymphoma (NHL) to examine whether the long-term disease-free survival (DFS) rate can be improved for patients with poor-prognosis intermediate/high-grade NHL. PATIENTS AND METHODS: Twenty-six patients with advanced-stage diffuse intermediate/high-grade B-cell NHL (including 16 patients with diffuse small cleaved-cell [DSC]) were selected at presentation by histologic and clinical characteristics to have less than a 25% probability of long-term DFS with conventional treatment. After induction chemotherapy, 16 patients were in complete remission (CR) and 10 were in a minimal disease state. Patients were then treated with high-dose cyclophosphamide, total-body irradiation (TBI), and anti-B-cell monoclonal antibody-purged ABMT. RESULTS: Following ABMT, no acute in-hospital treatment deaths occurred, and engraftment of granulocytes and platelets was significantly faster than for patients undergoing ABMT who were in second or subsequent remission. Of 26 patients, 21 remain in CR maintained without continued therapy, three relapsed in sites of prior nodal disease (4.8, 5.4, and 28 months post-ABMT), and two died in remission. The DFS rate is estimated to be 85% at 28 months and thereafter. The median follow-up period for the 21 patients who are alive and disease-free is 32 months. CONCLUSION: This pilot study suggests that consolidation of first remission with ABMT may improve the long-term DFS rate for diffuse intermediate/high-grade NHL patients at high risk for relapse.

Adult↗

PubMed1993

Monoclonal antibody-purged autologous bone marrow transplantation in adults with acute lymphoblastic leukemia at high risk of relapse.

The prognosis for adults with B lineage ALL who have relapsed after an initial remission is poor. High-dose chemoradiotherapy followed by autologous BMT can induce prolonged clinical remissions in some children with recurrent ALL. In this study, we evaluated the efficacy of autologous BMT in adults. Autologous marrow was treated in vitro with J5 and J2 monoclonal antibodies (CD10/CD9) plus rabbit complement to purge residual ALL cells. Twenty-two adults with B lineage ALL were treated with high-dose chemoradiotherapy followed by infusion of J2/J5 purged autologous BM. The median age was 28 years (range 18-54 years). Twenty-one of 22 patients had experienced at least one relapse prior to BMT. All patients achieved complete hematologic engraftment. Disease-free survival (DFS) in this cohort of patients was 20%, with all survivors alive and free of disease between 2.5 and 7.5 years post-BMT. Age at the time of BMT was an important prognostic factor, with patients < 28 years old faring much better than older individuals (DFS, 45% vs 0%, p = 0.01). Our experience suggests that high-dose chemoradiotherapy followed by infusion of J2/J5 purged autologous marrow is as efficacious in young adults as it is in children and is a reasonable alternative for patients who lack HLA-matched donors. Results in older adults are poor, however, and demonstrate the need for more effective transplant strategies in these individuals.

Adolescent↗

PubMed1992

Participation of the CD27 antigen in the regulation of IL-2-activated human natural killer cells.

The CD27 Ag is expressed by the majority of resting T lymphocytes and appears to play a crucial role in T cell activation. We found that some resting peripheral blood NK cells also express CD27. Furthermore, CD27 expression was up-regulated on NK cells stimulated by IL-2. The cytolytic activity of IL-2-activated, but not resting, NK cells was inhibited by an anti-CD27 mAb (anti-1A4). However, anti-1A4 did not affect conjugate formation between IL-2-activated NK cells and tumor cell targets. In contrast, anti-1A4 inhibited CD2-mediated calcium mobilization and the serine esterase activity of NK cell granules. These inhibitory effects could be mediated in part by increase in intracellular cAMP levels induced by anti-1A4. Our results suggest that the CD27 Ag plays an important role in the regulation of activated NK cells.

Antigens, CD↗

PubMed1992

Human bone marrow depleted of CD33-positive cells mediates delayed but durable reconstitution of hematopoiesis: clinical trial of MY9 monoclonal antibody-purged autografts for the treatment of acute myeloid leukemia.

The CD33 antigen, identified by murine monoclonal antibody anti-MY9, is expressed by clonogenic leukemic cells from almost all patients with acute myeloid leukemia; it is also expressed by normal myeloid progenitor cells. Twelve consecutive patients with de novo acute myeloid leukemia received myeloablative therapy followed by infusion of autologous marrow previously treated in vitro with anti-MY9 and complement. Anti-MY9 and complement treatment eliminated virtually all committed myeloid progenitors (colony-forming unit granulocyte-macrophage) from the autografts. Nevertheless, in the absence of early relapse of leukemia, all patients showed durable trilineage engraftment. The median interval post bone marrow transplantation (BMT) required to achieve an absolute neutrophil count greater than 500/microL was 43 days (range, 16 to 75), to achieve a platelet count greater than 20,000/microL without transfusion was 92 days (range, 35 to 679), and to achieve red blood cell transfusion independence was 105 days (range, 37 to 670). At the time of BM harvest, 10 patients were in second remission, one patient was in first remission, and one patient was in third remission. Eight patients relapsed 3 to 18 months after BMT. Four patients transplanted in second remission remain disease-free 34+, 37+, 52+, and 57+ months after BMT. There was no treatment-related mortality. Early engraftment was significantly delayed in patients receiving CD33-purged autografts compared with concurrently treated patients receiving CD9/CD10-purged autografts for acute lymphoblastic leukemia or patients receiving CD6-purged allografts from HLA-compatible sibling donors. In contrast, both groups of autograft patients required a significantly longer time to achieve neutrophil counts greater than 500/microL and greater than 1,000/microL than did patients receiving normal allogeneic marrow. CD33(+)-committed myeloid progenitor cells thus appear to play an important role in the early phase of hematopoietic reconstitution after BMT. However, our results also show that human marrow depleted of CD33+ cells can sustain durable engraftment after myeloablative therapy, and provide further evidence that the CD33 antigen is absent from the human pluripotent hematopoietic stem cell.

Adult↗

PubMed1992

Response of human natural killer (NK) cells to NK cell stimulatory factor (NKSF): cytolytic activity and proliferation of NK cells are differentially regulated by NKSF.

Natural killer cell stimulatory factor (NKSF) is a 70-kD heterodimeric cytokine that was initially isolated from conditioned medium of human B lymphoblastoid cell lines. The effects of recombinant NKSF on the function of human peripheral blood NK cells were examined. NKSF directly augmented the cytolytic activity of freshly isolated NK cells. Both CD56dim and CD56bright NK cells demonstrated enhanced cytotoxicity after brief exposure to NKSF. In contrast, highly purified T lymphocytes did not exhibit major histocompatibility complex-unrestricted cytotoxicity after short-term culture with NKSF. Like interleukin 2 (IL-2), NKSF augmented the lysis of NK-sensitive, NK-resistant, and antibody-coated targets. Both NKSF and IL-2 induced marked upregulation of several NK cell adhesion molecules known to participate in cytolysis, including CD2, CD11a, and CD54. However, NKSF activates NK cells through a pathway distinct from that of IL-2, since the presence of anti-IL-2 receptor (anti-IL-2R) antibodies or IL-4 did not inhibit the effects of NKSF. NKSF by itself induced very little proliferation of resting NK cells. NK cells preactivated in vitro with IL-2 demonstrated enhanced proliferation to NKSF, but the degree of proliferation was always inferior to that induced by IL-2 alone. Moreover, NKSF strongly inhibited IL-2-induced proliferation of either resting or preactivated NK cells. This inhibition was not the result of decreased IL-2R expression, because NKSF-activated NK cells expressed higher levels of both IL-2Rs p75 and p55. Furthermore, NKSF did not inhibit the proliferation of mitogen-activated T cells, indicating a selective effect on NK cell proliferation. Human NK cells expanded in vivo by prolonged continuous infusions of IL-2 remained fully responsive to NKSF. Picomolar concentrations of NKSF were as effective as nanomolar concentrations of IL-2 in augmenting the cytolytic activity of NK cells expanded in vivo by IL-2. NKSF may play an important role in the regulation of human NK cell function, and its possible use as a therapeutic cytokine deserves further investigation.

Humans↗

PubMed1992

Differential responses to interleukin 2 define functionally distinct subsets of human natural killer cells.

Human natural killer (NK) cells can be subdivided into two populations based on the density of cell surface CD56 antigen. The great majority (approximately 90%) of NK cells express CD56 at low levels (the CD56dim phenotype), whereas a small NK cell subset (approximately 10%) exhibits approximately fivefold greater density of surface CD56. Exposure to exogenous interleukin 2 (IL 2) induces tenfold greater proliferation of CD56bright cells compared to CD56dim lymphocytes, even though both subsets constitutively express similar levels of intermediate affinity IL 2 receptor (IL 2R) p75 chains. Incubation with IL 2 alone or irradiated target cells alone could induce expression of the IL 2R p55 chain by both CD56bright and CD56dim NK cells; a combination of both stimuli was most effective. IL 2R p55 induction was evident after co-culture of NK cells with both NK-sensitive and NK-resistant cell lines or with antibody-coated target cells. Activation of NK cells with IL 2 plus target cells resulted in enhanced proliferation compared to activation with IL 2 alone; target cells alone did not induce significant proliferation. Although both NK cell subsets appeared to express high-affinity IL 2R p75/p55 heterodimers after stimulation with target cells and IL 2, proliferation of CD56dim cells remained minimal after such activation; activated CD56dim cells consistently demonstrated less proliferation to IL 2 than did resting CD56bright cells. In contrast, CD56bright NK cells exhibited even greater proliferation after stimulation with target cells. Almost all CD56dim NK cells expressed CD16 (Fc gamma R III) as well as the NK zeta chain, whereas less than 50% of CD56bright cells express either CD16 or zeta. CD56bright and CD56dim lymphocytes, thus, appear to represent distinct subpopulations of NK cells with different functional activities. Unlike CD56bright cells, CD56dim NK cells do not proliferate optimally to IL 2, even after the latter have been stimulated to express both IL 2R p55 and IL 2R p75. Efficient proliferation of CD56dim NK cells may, thus, require additional or alternative signals.

Antibody-Dependent Cell Cytotoxicity↗

PubMed1992

A comparison of the characteristics of angiotensin receptors in the renal and mesenteric vascular beds of the anesthetized cat.

Experiments were performed in anesthetized cats to compare the characteristics of angiotensin receptors in the renal and mesenteric vascular beds. Injection of either angiotensin II (Ang II; 0.3-30 ng) or angiotensin III (Ang III; 0.3-30 ng) directly into the superior mesenteric or renal artery caused dose-related, reproducible reductions in mesenteric and renal blood flow, respectively. Ang II and Ang III were equipotent as vasoconstrictors in both vascular beds. The peptide angiotensin receptor antagonists saralasin and Ile7-Ang III (1 microgram/kg/min intravenously, i.v.) and the nonpeptide angiotensin receptor antagonist DuP 753 (3 mg/kg plus 20 micrograms/kg/min i.v.) caused a rightward displacement of dose-response curves to Ang II or Ang III in both the mesenteric and renal vasculature. Vasoconstrictor responses to Ang II or Ang III in either vascular bed were blocked to similar extents by each antagonist. In separate cats, the dose of the antagonists required to cause a 10-fold rightward displacement of the Ang II dose-response curve (DR10) in both vascular beds was determined. The DR10 values indicated that the potency of each antagonist was similar in the renal and mesenteric vascular beds. These results provide no evidence to suggest that angiotensin receptors mediating vasoconstriction in the renal and mesenteric vasculature have different characteristics.

Angiotensin II↗

PubMed1992

Pharmacological profile of GR117289 in vitro: a novel, potent and specific non-peptide angiotensin AT1 receptor antagonist.

1. This paper describes the effects of GR117289 (1-[[3-bromo-2-[2-(1H-tetrazol-5-yl)phenyl]-5-benzo-furanyl]methyl ]-2-butyl-4-chloro-1H-imidazole-5-carboxylic acid) at angiotensin receptors and binding sites in rabbit aorta, rat liver and bovine cerebellum preparations in vitro. 2. In rabbit isolated aortic strips, GR117289 (0.3, 1 and 3 nM) caused a concentration-related, insurmountable suppression of the concentration-response curve to angiotensin II (AII). When the contact time was increased, a greater degree of antagonism of AII was observed, suggesting that GR117289 is slow to reach equilibrium. A pKB of 9.8 +/- 0.1 was calculated for GR117289 after 3 h incubation. GR117289 (1 microM) did not affect contractile responses to phenylephrine or 5-hydroxytryptamine (5-HT) in the rabbit aorta. 3. GR117289 (1 nM) alone caused a marked suppression and a slight rightward displacement of the AII concentration-response curve. Co-incubation with the competitive, surmountable AT1 receptor antagonist, losartan (10 nM, 100 nM and 1 microM), resulted in a concentration-related upward and rightward displacement of the concentration-response curve to subsequently administered AII. In separate experiments in which preparations were pre-incubated with GR117289 (1 nM), subsequent addition of losartan (1 microM) for 2, 15 or 45 min caused a further, but similar, rightward displacement of the concentration-response curve to subsequently administered AII with a time-dependent increase in the maximum response.4. Suppression of All-induced contractile responses, caused by superfusion with GRI17289 (0.3, 1 or 3 nM) was not reversed by continuously washing the tissues for 3 h; in fact, the potency of GRI 17289 was slightly enhanced after this period.5. In rat liver membranes, GRI17289 was a potent competitor with [3H]-AII for AT, binding sites(pKi = 8.7 +/- 0.1) but in bovine cerebellum membranes, it was a very weak competitor for AT2 binding sites (pKi<6). Pre-incubation of rat liver membranes with GRI17289 had little effect on its affinity(pKi = 9.1 +/- 0.21), but increasing the concentration of bovine serum albumen in the assay buffer from 0.001% to 0.1% w/v decreased affinity (pKi= 7.5 +/- 0.1).6. In saturation binding experiments in rat liver membranes, GRI 17289 (12 nM) increased the Kd of[3H]-AII from 0.28 +/- 0.06 nM to 0.37 +/- 0.02 nM, and decreased Bm. from 10.0 +/- 0.1 to 5.6 +/-0.3 fmol mg' tissue. In other experiments, GR1 17289 (1 jIM) did not alter the rate of dissociation of[3H]-AII from AT1 binding sites, following addition of excess unlabelled All.7. In rabbit aorta vascular smooth muscle membranes, GR1 17289 competed with ['25I]-Sar'1le8 All for binding to AT, binding sites. In the presence of 0.1% w/v bovine serum albumen, a pIC50 of 7.6 +/- 0.1 was calculated. Under the same conditions, but with rat liver membranes, a pIC50 of 7.8 +/- 0.1 was determined.8. Taken together, these results show that GRI17289 is a potent, specific, selective and insurmountable antagonist at angiotensin AT, receptors. Its profile in the rabbit aorta is consistent with the proposalthat GRI17289 is a slowly reversible (pseudo-irreversible) antagonist at these receptors.

Angiotensin II↗

PubMed1992

Effects of peptidase inhibition on angiotensin receptor agonist and antagonist potency in rabbit isolated thoracic aorta.

1. Experiments were performed with peptidase inhibitors on rabbit aortic strip preparations, to determine whether endogenous peptidase activity can influence the potency estimates for angiotensin receptor agonists and antagonists in this tissue. 2. Angiotensin II (A II) and angiotensin III (A III) both induced concentration-related contractions of rabbit aortic strip preparations. A III was approximately 38 fold less potent than A II, and the gradient of the A III concentration-response curve (1.00 +/- 0.04) was significantly more shallow than that (1.76 +/- 0.05) of the A II curve. 3. Neither the aminopeptidase-A and -M inhibitor, amastatin, nor the aminopeptidase-B and -M inhibitor, bestatin, affected the potency of, or the maximum response to, A II. In contrast, the potency of A III was increased by both amastatin and bestatin. Amastatin had the most marked effect and at 10 microM caused approximately a 12 fold increase in the potency of A III (EC50 values, 102 nM and 8.6 nM in the absence and presence of amastatin, respectively), and also significantly steepened the gradient of the A III concentration-response curve. Amastatin did not affect the position or shape of the concentration-response curve to the alpha 1-adrenoceptor agonist, phenylephrine. Finally, the carboxypeptidase-N inhibitor, D-L-mercaptomethyl-3-guanidine-ethylpropanoic acid (MERGETPA) did not change the position or shape of the concentration-response curves to either A II or A III.4. In the presence of amastatin, the potency of the peptide angiotensin receptor antagonist, Ile7-A III (100nM-l microM ), was increased approximately 13 fold (pA2, with A II as the agonist, 7.0 +/- 0.1 and 8.1 +/- 0.1, in the absence and presence of amastatin, respectively). However, the potency of the nonpeptide angiotensin receptor antagonist, DuP 753 (30-300 nM), was little affected by amastatin (pA2, 8.2 +/- 0.1 and 8.1 +/- 0.1 in the absence and presence of amastatin, respectively).5. The results of this study suggest that endogenous aminopeptidase activity in the rabbit thoracic aorta can profoundly affect estimates of the potency of peptide angiotensin receptor agonists and antagonists.A suitable aminopeptidase inhibitor should therefore be included in studies, using this tissue, which aim to classify angiotensin receptor subtype(s) based on the rank order of peptide angiotensin receptor agonist and/or antagonist potencies.

3-Mercaptopropionic Acid↗

PubMed1992

Prevention of graft-versus-host disease by selective depletion of CD6-positive T lymphocytes from donor bone marrow.

PURPOSE: Acute and chronic graft-versus-host disease (GVHD) continues to be the major causes of morbidity and mortality after allogeneic bone marrow transplantation (BMT). In this study, we have evaluated the clinical effects of selective in vitro T-cell depletion of donor allogeneic bone marrow by using a single monoclonal antibody ([MoAb] anti-T12, CD6) and rabbit complement. This antibody recognizes mature T cells, but not other cellular elements such as natural-killer (NK) cells, B cells, and myeloid precursors. PATIENTS AND METHODS: From August 1983 to April 1991, 112 consecutive adult patients with hematologic malignancies underwent BMT with bone marrow from HLA-identical sibling donors. Marrow was harvested and depleted of mature T lymphocytes ex vivo by the use of three rounds of incubation with an anti-T12 antibody and rabbit complement. The preparative regimen consisted of cyclophosphamide and fractionated total body irradiation (TBI) in 108 patients. No patients received prophylactic immune suppression post-BMT. Purgation by anti-T12 was used as the only method for the prevention of GVHD. RESULTS: Twenty patients (18%) developed acute GVHD (grade 2 to 4); only eight patients developed chronic GVHD. The incidence of GVHD did not increase significantly with age. Only three of 112 patients (2.7%) exhibited acute graft failure. One patient developed late graft failure that was associated with cytomegalovirus (CMV) infection. Within the subset of 50 patients who had not previously undergone unsuccessful conventional therapy (acute leukemia in first remission or chronic myelogenous leukemia [CML] in stable phase), we estimated by the Kaplan-Meier method that the probability of disease-free survival was 50% at 3 years post-BMT, with a median follow-up of 44 months. The treatment-related mortality rate in this group was only 14% and was independent of patient age. CONCLUSIONS: We conclude that selective in vitro T-cell depletion with an anti-T12 monoclonal antibody effectively reduces the incidence of both acute and chronic GVHD after allogeneic BMT without compromising engraftment. Moreover, depletion of CD6-positive cells from donor marrow obviates the need to administer immune suppressive medications to the majority of patients. This approach reduces the morbidity and mortality of allogeneic BMT and permits the BMT of older patients.

Adult↗