Biomedical subjects

J Ritz

Publications and source records attributed to J Ritz.

At least 73 records · Page 4Linked to original sources

PubMed1997

Phase I evaluation of intravenous recombinant human interleukin 12 in patients with advanced malignancies.

A Phase I dose escalation trial of i.v. administered recombinant human interleukin 12 (rhIL-12) was performed to determine its toxicity, maximum tolerated dose (MTD), pharmacokinetics, and biological and potential antineoplastic effects. Cohorts of four to six patients with advanced cancer, Karnofsky performance >/=70%, and normal organ function received escalating doses (3-1000 ng/kg/day) of rhIL-12 (Genetics Institute, Inc.) by bolus i.v. injection once as an inpatient and then, after a 2-week rest period, once daily for five days every 3 weeks as an outpatient. Therapy was withheld for grade 3 toxicity (grade 4 hyperbilirubinemia or neutropenia), and dose escalation was halted if three of six patients experienced a dose-limiting toxicity (DLT). After establishment of the MTD, eight more patients were enrolled to further assess the safety, pharmacokinetics, and immunobiology of this dose. Forty patients were enrolled, including 20 with renal cancer, 12 with melanoma, and 5 with colon cancer; 25 patients had received prior systemic therapy. Common toxicities included fever/chills, fatigue, nausea, vomiting, and headache. Fever was first observed at the 3 ng/kg dose level, typically occurred 8-12 h after rhIL-12 administration, and was incompletely suppressed with nonsteroidal anti-inflammatory drugs. Routine laboratory changes included anemia, neutropenia, lymphopenia, hyperglycemia, thrombocytopenia, and hypoalbuminemia. DLTs included oral stomatitis and liver function test abnormalities, predominantly elevated transaminases, which occurred in three of four patients at the 1000 ng/kg dose level. The 500 ng/kg dose level was determined to be the MTD. This dose, administered by this schedule, was associated with asymptomatic hepatic function test abnormalities in three patients and an onstudy death due to Clostridia perfringens septicemia but was otherwise well tolerated by the 14 patients treated in the dose escalation and safety phases. The T1/2 elimination of rhIL-12 was calculated to be 5.3-9.6 h. Biological effects included dose-dependent increases in circulating IFN-gamma, which exhibited attenuation with subsequent cycles. Serum neopterin rose in a reproducible fashion regardless of dose or cycle. Tumor necrosis factor alpha was not detected by ELISA. One of 40 patients developed a low titer antibody to rhIL-12. Lymphopenia was observed at all dose levels, with recovery occurring within several days of completing treatment without rebound lymphocytosis. There was one partial response (renal cell cancer) and one transient complete response (melanoma), both in previously untreated patients. Four additional patients received all proposed treatment without disease progression. rhIL-12 administered according to this schedule is biologically and clinically active at doses tolerable by most patients in an outpatient setting. Nonetheless, additional Phase I studies examining different schedules and the mechanisms of the specific DLTs are indicated before proceeding to Phase II testing.

Adult↗

PubMed1996

TEL/AML-1 dimerizes and is associated with a favorable outcome in childhood acute lymphoblastic leukemia.

Polymerase chain reaction-based screening of childhood acute lymphoblastic leukemia (ALL) samples showed that a TEL/AML1 fusion transcript was detected in 27% of all cases, representing the most common known gene rearrangement in childhood cancer. The TEL/AML1 fusion results from a t(12;21)(p13;q22) chromosomal translocation, but was undetectable at the routine cytogenetic level. TEL/AML1-positive patients had exclusively B-lineage ALL, and most patients were between the ages of 2 and 9 years at diagnosis. Only 3/89 (3.4%) adult ALL patients were TEL/AML1-positive. Most importantly, TEL/AML1-positive children had a significantly lower rate of relapse compared with TEL/AML1-negative patients (0/22 v 16/54, P = .004). Co-immunoprecipitation experiments demonstrated that TEL/AML-1 formed homodimers in vitro, and heterodimerized with the normal TEL protein when the two proteins were expressed together. The elucidation of the precise mechanism of transformation by TEL/AML1 and the role of TEL/AML1 testing in the treatment of childhood ALL will require additional studies.

Adolescent↗

PubMed1996

Prevention of transmission of hepatitis C virus in bone marrow transplantation by treating the donor with alpha-interferon.

Transmission of hepatitis C virus (HCV) in the setting of allogeneic bone marrow transplantation can occur through an infected marrow donor. Prevention of transmission may reduce the risks of peritransplant complications. We describe a 43-year-old patient with chronic myelogenous leukemia whose HLA-identical donor was found to be HCV antibody positive and HCV RNA positive by polymerase chain reaction (PCR). The patient was HCV antibody negative and HCV RNA negative by PCR of the serum. For 6 months before bone marrow transplantation, the donor was treated with alpha-interferon at a standard dose. After 3 months, HCV RNA was no longer detectable by PCR. Interferon was discontinued 1 week before harvest. Bone marrow cellularity was normal. Engraftment was prompt. The recipient's serum remained negative for HCV RNA at 1, 3, 5, and 10 months after transplantation. Hepatitis C transmission from a viremic donor to an HCV-seronegative recipient may be preventable by treating the donor with alpha-interferon.

Adult↗

PubMed1996

CD2-CD58 interaction and the control of T-cell interleukin-12 responsiveness. Adhesion molecules link innate and acquired immunity.

Interleukin-12 is an antigen-presenting cell (APC)-derived cytokine that stimulates T helper cell type 1 (Th1) differentiation as well as proliferation, cytolytic activity, and IFN-gamma production among T and natural killer (NK) cells. By immunizing mice with activated T cells and screening for antibodies that could inhibit IL-12-induced proliferation, CD2 was identified as a regulator of T-cell IL-12 responsiveness. Antibodies specific for the adhesion domain of either CD2 or its primary ligand, CD58, inhibited the major functional responses of T cells to IL-12 without affecting the response to IL-2. This inhibition did not involve any alteration in IL-12 binding to T cells. The CD2-CD58 interaction between activated T cells and monocytes was found to be a critical factor in the modulation of T-cell IL-12 responsiveness, and experiments using CD58-transfected Chinese hamster ovary (CHO) cells, and stimulatory pairs of CD2 antibodies confirmed the key role of CD2 ligation in optimizing T-cell IL-12 signaling. These findings illustrate how APCs, through the differential expression of a specific adhesion molecule, can control the T-cell response to a cytokine independent of cytokine receptor expression. This has important implications for an understanding of Th1 development and the conditions required to link innate with acquired immune responses.

Animals↗

PubMed1996

High-dose therapy and autologous bone marrow transplantation in patients with follicular lymphoma during first remission.

We report the results of a study in previously untreated advanced stage patients with follicular lymphoma (FL) who underwent uniform induction chemotherapy with cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) followed by myeloablative therapy and anti-B-cell monoclonal antibody purged autologous bone marrow transplantation (ABMT). Eighty-three patients with previously untreated, low-grade FL were enrolled. After CHOP induction, only 36% achieved complete remission (CR) and 77 patients underwent ABMT. Before BM harvest, 70 patients had a known t(14;18), as determined by polymerase chain reaction (PCR), and all remained PCR positive in the BM at harvest. After ABMT, the disease-free survival (DFS) and overall survival are estimated to be 63% and 89% at 3 years, respectively, with a median follow-up of 45 months. Patients whose BM was PCR negative after purging experienced significantly longer freedom from recurrence (FFR) than those whose BM remained PCR positive (P = .0006). Continued PCR negativity in follow-up BM samples was also strongly predictive of continued CR. This study suggests that a subset of patients with advanced FL may experience prolonged clinical and molecular remissions following high-dose ablative therapy, although longer follow-up will be necessary to determine potential impact on overall survival.

Adult↗

PubMed1996

Eradication of polymerase chain reaction-detectable chronic lymphocytic leukemia cells is associated with improved outcome after bone marrow transplantation.

In chronic lymphocytic leukemia (CLL), clonal rearrangement of the immunoglobulin heavy chain locus (IgH) provides a useful marker for the detection of minimal residual disease (MRD) after treatment. At the time of initial presentation, DNA from patients with CLL was polymerase chain reaction (PCR)-amplified using consensus Variable (VH) and Joining (JH) region primers using complementarity determining region III consensus region primers or a panel of VH family-specific framework region 1 (FR1) primers. The clonal product was directly sequenced and patient-specific probes constructed using N region nucleotide sequences. We amplified and sequenced the CDRIII region and designed patient specific oligonucleotide probes for the detection of MRD in 55 of 66 patients (84%, 90% Confidence Intervals (CI): 74% to 90%) with poor prognosis CLL referred for autologous and allogeneic bone marrow transplantation (BMT). To determine the clinical utility of this technique, PCR amplification was performed on patient samples at the time of and following autologous (21 patients) and allogeneic (10 patients) BMT in whom serial bone marrow samples obtained after BMT were available for analysis. We show that the persistence of MRD after BMT is associated with increased probability of relapse. In all cases that have relapsed to date, the IgH CDRII region was identical at the time of initial presentation and at relapse suggesting that clonal evolution of the IgH locus is unusual in this disease. The finding that a significant number of patients remain disease free and with no evidence of PCR-detectable MRD after BMT suggests that high-dose therapy may contribute to improved outcome in selected patients with CLL.

Base Sequence↗

PubMed1996

Defective activation of mitogen-activated protein kinase after allogeneic bone marrow transplantation.

Allogeneic bone marrow transplant (BMT) recipients have increased susceptibility to infections for prolonged periods after phenotypic reconstitution of donor cells. This immunodeficiency status is characterized by multiple T-cell functional abnormalities. This study was designed to investigate several signaling pathways involved in T-cell activation during this period of immune deficiency. In initial experiments using equal numbers of CD3+ cells or highly purified T-cell subpopulations obtained from normal controls and BMT recipients, we confirmed that abnormal T-cell proliferation after CD3 cross-linking, phytohemagglutinin stimulation, or phorbol myristate acetate (PMA) stimulation of peripheral blood mononuclear cells from BMT recipients was due to a qualitative T-cell deficiency rather than to low numbers of circulating T cells. We next investigated the ability of the T-cell receptor/CD3 complex to transduce signals via receptor-associated protein tyrosine kinases. In all BMT recipients, CD3 cross-linking induced protein tyrosine phosphorylation of several proteins in a similar fashion to that seen in controls, including phosphorylation of a 21-kD protein that represents the zeta subunit of the receptor itself. Further investigation showed that CD3 cross-linking and PMA stimulation did not increase 42-44-kD mitogen-activated protein kinase (MAPK) activity. The failure of MAPK activation in BMT recipients occurred despite tyrosine phosphorylation of the 42-44-kD proteins, which, in normal controls, parallels enzyme activation. Our results indicate that T-cell immunodeficiency in BMT recipients is associated with a selective failure of MAPK activation, possibly related to abnormal posttranslational positive regulation of this enzyme.

Adult↗

PubMed1996

Molecular interaction between CD58 and CD2 counter-receptors mediates the ability of monocytes to augment T cell activation by IL-12.

IL-12 stimulates both T and NK cells and is pivotal in the development of the Th1 immune response. In this work, we show that an interaction between CD2 and CD58 on activated T cells and monocytes, respectively, regulates the T cell response to IL-12. B cells provide little IL-12-specific costimulation, and this correlates with the low level of CD58 on B cells relative to monocytes and the lack of significant up-regulation in response to IFN-gamma or PHA activation. CHO cell transfectants expressing CD58 at a level comparable with that found on monocytes restore IL-12 responsiveness to APC-depleted T cells. This effect is not observed with CHO cells expressing CD48, a second CD2 ligand with a low avidity for CD2 relative to CD58. Thus, in addition to augmenting adhesion between T cells and their cognate APCs and facilitating TCR-triggered activation, the CD2-CD58 interaction uniquely optimizes the T cell response to IL-12.

Adjuvants, Immunologic↗

PubMed1996

Transcript synthesis and surface expression of the interleukin-2 receptor (alpha-, beta-, and gamma-chain) by normal and malignant myeloid cells.

Expression of the interleukin-2 receptor alpha-(IL-2Ralpha-), IL-2Rbeta-, and the recently identified IL-2Rgamma-chain was examined on a wide range of cells of myeloid origin including neutrophils, monocytes, normal bone marrow-derived myeloid progenitors enriched for CD34+ cells, bone marrow blasts obtained from acute myelogenous leukemia (AML) patients, and permanent myeloid leukemia cell lines by reverse transcriptase-polymerase chain reaction and surface membrane analysis using receptor chain-specific monoclonal antibodies and flow cytometry. Expression of the p75 IL-2Rbeta- and the p64 IL-2Rgamma-chain was a common finding in most of the myeloid cell samples investigated, whereas IL-2Ralpha-chain was less frequently expressed. Although the high-affinity IL-2R form (ie, the alpha+, beta+, gamma+ IL-2R form) was detectable in a small minority of primary AML samples as well as the KG-1 cell line and IL-2 binding to these cells was sufficient to initiate signal transduction as evidenced by an increase in overall protein tyrosine phosphorylation and more specifically in tyrosine phosphorylation of the Janus kinase (JAK) 3, in none of these cell types did exposure to IL-2 affect cell growth kinetics. These results suggest that, in myeloid cells, the IL-2R may not stimulate mitogenic responses or that its components may be expressed in a combinational association with receptors for other cytokines and that IL-2Rgamma may play a regulatory role in normal and malignant myelopoiesis possibly independent from IL-2. Because recent studies by others have indicated that the IL-2Rgamma- chain may be shared by the IL-4R, the IL-7R, and most likely the IL-9R, expression of mRNA of these receptor types was also investigated in these cell samples. Surprisingly, in a substantial part of the myeloid lineage cells examined, an IL-2Rgamma+, IL-4R-, IL7R- configuration was noted that was, however, frequently associated with expression of IL-9R. Sharing of IL-9R/IL-2R components was furthermore suggested by inhibition of 125I-IL-2 binding to primary AML cells with excess of unlabeled IL-9.

Acute Disease↗

PubMed1996

R24 anti-GD3 ganglioside antibody can induce costimulation and prevent the induction of alloantigen-specific T cell clonal anergy.

R24 is a monoclonal antibody directed against the cell surface ganglioside GD3. It can detect GD3 on the surface of a subset of T lymphocytes and can stimulate proliferation and secretion of cytokines in vitro. In the present report, we examined the effects of the R24 antibody upon antigen-specific T cell response, employing an HLA-DR7-specific T cell clonal model. As previously shown, primary stimulation of HLA-DR7-specific alloreactive T cell clones by transfectants expressing HLA-DR7 alone (t-DR7) in the absence of B7 co-stimulation resulted in anergy. Binding of cell surface GD3 on HLA-DR7-specific alloreactive T cell clones with R24 under these anergizing conditions resulted in interleukin-2 (IL-2) accumulation and prevented the induction of alloantigen-specific T cell clonal anergy. Binding of GD3 by R24 also prevented anergy under conditions where B7:CD28 interactions were blocked by CTLA4-Ig. The effect of R24 was abrogated in the presence of a combination of monoclonal antibodies for the alpha and beta chains of the IL-2 receptor (IL-2R) or a neutralizing anti-IL-2 antibody. R24 does not appear to interact directly with the IL-2R since incubation of T cell clones with R24 did not induce early activation of IL-2R associated Jak kinases, Jak1 and Jak3, as was induced following incubation with IL-2. In contrast, incubation of HLA-DR7-specific clones with t-DR7 in the presence of R24 did result in phosphorylation of IL-2R related Jak kinases after 24 h. Our data indicate that the membrane ganglioside GD3 structure recognized by R24 may play an important role in antigen-specific T cell clonal response.

3T3 Cells↗

PubMed1996

Surgical therapy of gastrointestinal non-Hodgkin's lymphomas.

Within a period of 13 years 39 patients underwent surgery for primary gastrointestinal non-Hodgkin's lymphoma. The stomach was the most frequent site of involvement (26 cases) followed by the small intestine (10 cases) and the large bowel (three cases). Operative procedures included: total gastrectomy (n = 19), subtotal gastrectomy (n = 5), partial gastrectomy (n = 2), small bowel resection (n = 7), right hemicolectomy (n = 5) and sigmoid resection (n = 1). According to Musshoff's modification of the Ann Arbor system, we found stage I in nine, stage II in 12, stage III in two and stage IV in 16 patients. Histological typing according to the Kiel classification showed low-grade malignancy in 11 cases and high-grade in 28. Twenty-eight patients received chemotherapy and/or radiation in accordance with the tumour staging and type of malignancy. The follow-up data were analysed by the method of Kaplan and Meier. Including five patients who died post-operatively from perforated or bleeding lymphomas, the overall 5-year survival rate was 53.8%.

Adult↗

PubMed1996

Evidence against T-cell development in the adult human intestinal mucosa based upon lack of terminal deoxynucleotidyltransferase expression.

Several lines of evidence indicate that a subset of murine intestinal intraepithelial lymphocytes (iIEL), particularly those which express the CD8 alpha alpha homodimer, mature extrathymically. This study confirms that a small fraction of adult human iIEL also express the CD8 alpha alpha homodimer and demonstrates that most of these cells in the small intestine are T cells using the alpha beta T-cell receptor (TCR). Whether these cells or other subsets of adult human iIEL mature extrathymically in the intestine was assessed by measuring the expression of terminal deoxynucleotidyltransferase (TdT), an enzyme expressed exclusively by immature lymphocytes. Very low levels of TdT message could be detected by polymerase chain reaction (PCR) amplification in some iIEL samples. The level of TdT expression was assayed by competitive PCR amplification and compared with thymocytes and peripheral blood lymphocytes. These measurements indicated that the number of immature T cells expressing TdT in the intestinal epithelium was less than one cell per 10(7) lymphocytes. This demonstrates that there are few if any TdT expressing immature T cells in the adult human intestinal mucosa and indicates, therefore, that T-cell development in the intestinal mucosa does not contribute significantly to the T-cell repertoire of the adult human intestine.

Adult↗

PubMed1996

Sources and sequelae of bacterial contamination of hematopoietic stem cell components: implications for the safety of hematotherapy and graft engineering.

BACKGROUND: It is important to compare the incidence of bacterial contamination of components collected from the peripheral blood or bone marrow (BM), as well as of components processed with or without cell selection or depletion, and to evaluate the sequelae of such contamination. STUDY DESIGN AND METHODS: Bacterial contamination rates were compared in 1380 untreated autologous peripheral blood progenitor cells (PBPCs), 291 untreated autologous BM samples, 916 monoclonal antibody (MoAb)-treated autologous and allogeneic BM samples, and in 45 autologous PBPC components from which the CD34+ cells were selected. Bacterial cultures were performed at sequential time points during the processing of MoAb-treated BM. RESULTS: Bacterial contamination was documented in 44 of 2632 components from 1593 patients (1.67% of components, 2.76% of patients) before cryopreservation. Although only 0.65% of untreated PBPCs were contaminated before cryopreservation, each patient was more likely to have given a contaminated PBPC component than a contaminated BM component (2.41% vs. 0%, p < 0.01). Bacterial contamination of MoAb-treated BM was greater during or after manipulation than it was before (2.33% vs. 0.77%, p < 0.05). At thawing, contamination was documented in 42 (1.97%) of 2136 components cultured. Ten (13.7%) of 73 patients who received hematopoietic progenitor cells that were contaminated before cryopreservation or at thawing developed fever or positive blood cultures within 48 hours of transfusion. Fever was associated with bacteremia in two cases, but no irreversible clinical sequelae were noted. CONCLUSION: These studies suggest that, despite careful attention to sterile procedures, low-level contamination of hematopoietic stem cell components can be introduced before or during manipulation as well as at thawing, and that standards for monitoring of the procedures for collection, processing, cryopreservation, thawing, and transfusion of hematopoietic progenitor cells are necessary.

Antibodies, Monoclonal↗

PubMed1996

Interleukin 12: Basic Biology and Potential Applications in Cancer Treatment.

Interleukin 12 is a heterodimeric cytokine that has potent effects on innate and adaptive immunity. Interleukin 12 induces interferon g secretion by T cells and natural killer cells, enhances the proliferation of activated T cells and natural killer cells, augments the cytolytic activity of cytotoxic T lymphocytes and natural killer cells, and supports the differentiation of Th1 helper effector cells. Interleukin 12 stimulates in vitro antitumor activity of lymphocytes from patients with cancer and in vivo antitumor activity in many murine tumor models. Current data indicate that CD4 T cells, CD8 T cells, natural killer cells and interferon g may contribute to the antitumor effects of interleukin 12 therapy. However, further investigation is required to elucidate the precise mechanisms involved in the antitumor activity of interleukin 12.

Journal Article↗

PubMed1996

Characterization of a cell line, NKL, derived from an aggressive human natural killer cell leukemia.

Cell line NKL was established from the the peripheral blood of a patient with CD3-CD16+CD56+ large granular lymphocyte (LGL) leukemia. The neoplastic LGL of this patient mediated natural killing and antibody-dependent cellular cytotoxicity (ADCC) and exhibited proliferative responses similar to normal CD16+CD56dim natural killer (NK) cells. The Morphology of NKL cells resembles that of normal activated NK cells. The karyotype of NKL is 47, XY, add (1) (q42), +6 del (6) (q15 q23), del (17) (p11). NKL cells express CD2, CD6, CD11a, CD26, CD27, CD29, CD38, CD43, CD58, CD81, CD94, CD95, class II MHC, and the C1.7.1 antigen, but do not express detectable levels of CD3, CD4, CD5, CD8, CD14, CD19, CD20, CD28, alpha/beta or gamma/delta T cell receptors on the cell surface. The density of the CD16, CD56, and CD57 antigens declined markedly on NKL cells during prolonged im vitro culture. Nevertheless, NKL cells can mediate ADCC as well as natural killing. NKL cells are strictly dependent on interleukin-2 (IL-2) for sustained growth and die if deprived of IL-2 for more than 7 days. NKL cells proliferate in response to concentrations of IL-2 as low as 1 pM, but an optimal proliferative response requires approximately 100 pM IL-2. NKL cells growing in the presence of IL-2 express abundant IL-2R alpha with little or no detectable IL-2 beta or gamma chain on the cell surface; NKL cells deprived of IL-2 express high levels of both IL-2R alpha and beta. IL-4, IL-7, and IL-12, unlike IL-2, do not maintain the viability of NKL cells. Furthermore, IL-1, IL-4, IL-6, IL-7, IL-12, tumor necrosis factor-alpha (TNF-alpha), interferon-alpha (IFN-alpha) and IFN-gamma do not support the growth of NKL cells. The NKL cell line may prove useful for studies of human NK cell biology.

Antigens, CD↗

PubMed1996

Expression of CD95 antigen and Bcl-2 protein in non-Hodgkin's lymphomas and Hodgkin's disease.

CD95 (APO-1/Fas) is a member of the superfamily that includes the nerve growth factor and tumor necrosis factor receptors, OX40, CD27, CD30, and CD40. Present on a minority of resting blood lymphocytes, CD95 expression is upregulated on activated T and B lymphocytes and natural killer cells, where binding of the antigen by anti-Fas and anti-APO-1 antibodies has been shown to induce apoptosis. This CD95-mediated apoptosis is at least partially inhibited by expression of the Bcl-2 protooncogene. To evaluate possible roles of CD95 and Bcl-2 in growth regulation of lymphoid neoplasms, we studied by immunohistochemistry the expression of CD95 and Bcl-2 in 67 B- and 5 T-cell lymphomas, and 10 cases of Hodgkin's disease. In all, 29 B and 2 T cell lymphomas, and 9 cases of Hodgkin's disease expressed CD95. Compared with diffuse large B-cell and Burkitt-like lymphomas, lowgrade B-cell lymphomas more frequently expressed CD95 (52% versus 26%; P < .005). None of the B-cell small lymphocytic lymphomas or mantle cell lymphomas expressed CD95, whereas the majority of follicle center lymphomas, extranodal marginal zone B-cell lymphomas, and immunocytomas were CD95+. Of the 29 CD95+ B-cell lymphomas, only 33% of the high-grade group coexpressed Bcl-2, compared with 87% of the low-grade group (P < .04). Two of three peripheral T-cell lymphomas--including one anaplastic large cell lymphoma--expressed CD95. Staining for CD95 was seen in 9 of 10 cases of Hodgkin's disease. The infrequent expression of CD95 in high-grade B-cell lymphomas suggests an association between loss of CD95 expression/function and a more aggressive tumor grade. Whereas frequent coexpression of Bcl-2 with CD95 may protect low-grade B-cell lymphomas against CD95-mediated apoptosis, in the high-grade group such coexpression is infrequent, and other regulators besides Bcl-2 may be involved in modulating the apoptosis signal delivered by CD95.

Animals↗

PubMed1996

Expansion and manipulation of natural killer cells in patients with metastatic cancer by low-dose continuous infusion and intermittent bolus administration of interleukin 2.

Interleukin 2 (IL-2) administered at low doses for prolonged periods can markedly expand the number of CD56(+) natural killer (NK) cells in patients with metastatic cancer. The cytotoxic capacity of NK cells obtained from patients receiving IL-2 in vivo can be dramatically augmented by additional exposure to IL-2 in vitro. These observations formed the basis of a clinical trial in which patients with metastatic cancer were treated with low-dose continuous daily infusions of IL-2 to increase the number of their NK cells in conjunction with intermittent boluses of additional IL-2 to stimulate this expanded pool of cytotoxic cells. Twenty-three patients were registered to receive IL-2 at 4.5 x 10(5) units/m2/day for 8 weeks by continuous i.v. infusion. After 4 weeks of "priming" with low-dose continuous infusion IL-2, cohorts of three to five patients received 5 weekly 2-h boluses of IL-2 at doses ranging from 2.5 x 10(5) units/m2 to 1.0 x 10(6) units/m2. Low-dose continuous infusion IL-2 was usually well tolerated; 2-h bolus infusions of IL-2 were often associated with high fevers and constitutional symptoms that resolved after several hours. Low-dose continuous infusion IL-2 resulted in the progressive expansion of circulating CD56(+)CD3(-) NK cells. In contrast, each bolus infusion of IL-2 resulted in an immediate dramatic decrease in both the number of NK cells and activated T lymphocytes with recovery noted within 24 h. Bolus doses of IL-2 as low as 2.5 x 10(5) units/m2 were capable of producing these effects. Cytolytic activity against NK-sensitive and -resistant targets correlated with the presence of circulating activated NK cells. Our results demonstrate that NK cells expanded by low-dose continuous infusions of IL-2 can be further activated in vivo by exposure to very low doses of IL-2 as a 2-h i.v. bolus. This capacity to manipulate human NK cells in vivo through varying the dose and schedule of IL-2 administration may help in defining the therapeutic potential of these cytotoxic effectors in the treatment of both neoplastic and infectious diseases.

Adult↗

PubMed1995

Phosphorylation of src family lck tyrosine kinase following interleukin-12 activation of human natural killer cells.

Interleukin-12 (IL-12) is a heterodimeric cytokine that augments the cytolytic activity of human NK cells and T cells but has little mitogenic activity on resting lymphocytes. The intracellular signaling pathways involved in NK cell activation by IL-12 have not been fully characterized. In the present studies we found that IL-12 induces tyrosine phosphorylation of a 56-kDa protein, identified in Western blot experiments as p56lck, in resting NK cells. IL-12 was active in the range of 0.1 to 1000 U/ml, with maximal activity between 10 and 100 U/ml (30 and 300 pM). The maximal effect was noted 5 min after stimulation and was almost completely inhibited by genistein. IL-12 induced similar effects in resting and IL-2 activated NK cells. Following IL-12 stimulation of resting NK cells, immunoprecipitated lck kinase exhibited increased in vitro autophosphorylation activity 5 and 10 min after activation. Several additional substrates were phosphorylated in vitro following IL-12 stimulation, including proteins of 70 and 110 kDa. These studies indicate that lck tyrosine kinase is involved in the IL-12 signaling pathway in human NK cells. As the primary functional effect of IL-12 on resting NK cells is the enhancement of cytolytic activity and secretory function rather than cell proliferation, these findings suggest that lck tyrosine kinase is involved in these signaling pathways in human NK cells.

Animals↗