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K Welte

Publications and source records attributed to K Welte.

At least 127 records · Page 7Linked to original sources
PubMed1990

A quantitative colorimetric method to evaluate the functional state of human polymorphonuclear leukocytes.

The colorimetric assay previously described by Mosmann for the measurement of cell viability and proliferation has been modified for the assessment of the functional state of human polymorphnuclear cells (PMNs). The ability of PMNs to reduce the tetrazolium salt MTT to formazan reflects directly the degree of stimulation induced by various agents. The underlying mechanism of MTT-reduction to formazan seems to be similar to that of nitroblue tetrazolium (NBT)-reduction. In contrast to the NBT-reduction assay, the formazan produced from MTT can easily be measured by an ELISA reader. Parallel experiments revealed a qualitative correlation between the concentration of formazan produced from MTT and the concentration of cytochrome C reduced by PMNs. Although oxidative burst may not be the actual lytic mechanism in cellular cytotoxicity of PMN, we also observed an association between MTT-reduction capacity and the cytotoxic activity of PMNs from normal donors in antibody dependent cellular cytotoxicity. Our results indicate that the MTT-reduction assay can be employed to estimate the functional state of polymorphnuclear granulocytes.

Cell Division↗
PubMed1990

A novel autoregulatory cytokine is required for the regulation of autoaggressive responses.

Limiting dilution studies indicate that cells with the potential to lyse autologous target cells exist in the peripheral blood of all normal individuals. In contrast to allocytotoxic cells, autocytolytic cells are down-regulated by a second less frequent cell population. When recombinant interleukin 2 is substituted for crude lymphocyte conditioned medium in these limiting dilution experiments, autocytotoxicity develops normally. Under these conditions, however, the autocytotoxic response is not down-regulated. Mixing crude lymphocyte-conditioned medium together with recombinant interleukin 2 restores the regulation of autocytotoxicity normally seen at high responder cell dose. These findings indicate that a second soluble factor present in the conditioned medium is necessary either for the activation, growth, or differentiation of the regulatory cell population or alternatively, to render the cytotoxic population responsive to the activity of regulatory cells. Gel filtration studies indicate that the molecular weight of this factor is between 60 and 80 kd. This factor appears to be distinct from known immunologically active cytokines. It is conceivable that deficiencies of this cytokine may be relevant to the pathogenesis of autoimmune diseases or graft-versus-host reactions.

Biological Factors↗
PubMed1990

A simple assay for quantifying the inducible adherence of neutrophils.

By making use of the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) reducing ability of stimulated human neutrophils, we developed an alternative method to quantify the adherence of neutrophils in vitro. After discarding non-adherent neutrophils, the adherent cells were exposed to MTT solution containing 10 ng/ml phorbol 12-myristate 13-acetone (PMA). Subsequently, MTT reduced by this simultaneous stimulation was measured optically and used to calculate percent of adhesion. In these experiments, heat-inactivated autologous serum and tumor necrosis factor alpha (rhTNF-alpha) were observed to promote the adherence to polystyrene surfaces. In contrast, minimal or no effects on neutrophil adherence were achieved in case of treatment with native autologous serum, recombinant human granulocyte colony stimulating factor (rhG-CSF), recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF), or recombinant human interferon gamma (rhIFN-gamma).

Biological Assay↗
PubMed1990

[The role of hematopoietic growth factors in the regulation of normal and pathological hematopoiesis].

Normal hematopoiesis is regulated by a family of hematopoietic growth factors that mediate the proliferation and maturation of blood cell precursors and pluripotential stem cells. Several of these factors have been isolated, biochemically characterized and are now being produced by recombinant DNA techniques in quantities sufficient for preclinical studies and clinical use. Three factors in particular have recently received considerable attention for their potential clinical use: granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF) and Multi-CSF or Interleukin 3 (IL-3). G-CSF is apparently lineage-specific for the proliferation of and differentiation of neutrophil granulocyte precursors. GM-CSF and IL-3 are less restricted in their action, affecting various lineages, such as eosinophil granulocytes, neutrophil granulocytes, monocytes, erythrocytes and megakaryocytes. The CSFs have many potential clinical applications including enhancing granulocyte production and function in neutropenic patients and rendering myeloid leukemic cells more susceptible to killing by cycle-specific agents.

Granulocyte Colony-Stimulating Factor↗
PubMed1990

[Bronchopulmonary diseases in primary immune deficiencies].

Data of 124 patients with primary immunodeficiencies were examined in a retrospective study in respect of incidence and severity of bronchopulmonary immunodeficiencies. Relapsing pneumonias were seen in 40 patients (32.3%) and bronchiectases in 15 cases (12.1%). Children with severe antibody deficiencies or combined immunodeficiencies were involved particularly often. Avoidance of pulmonary complications is of special prognostic importance with these patients.

Bronchitis↗
PubMed1989

Stimulation of human hematopoietic progenitor cell proliferation and differentiation by recombinant human interleukin 3. Comparison and interactions with recombinant human granulocyte-macrophage and granulocyte colony-stimulating factors.

Recombinant human interleukin 3 (IL3) produced in Escherichia coli was purified and its activities examined in cultures of highly enriched human bone marrow progenitor cells. Human IL3 stimulated multipotential (CFU-GEMM) and erythroid (BFU-E) progenitor cells, generating 95% more BFU-E than recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF). No further enhancement of BFU-E or CFU-GEMM occurred when IL3 and GM-CSF were used in combination. Human IL3 was more effective than GM-CSF in stimulating granulocyte-macrophage colony-forming cells (CFU-GM) in short-term suspension cultures, but did not induce an increase of CFU-GM, BFU-E, or CFU-GEMM above input levels. IL3 was more active on day-14 (d14) than on d7 CFU-GM, similar to GM-CSF, but generated fewer and smaller CFU-GM-derived clones than either GM-CSF or granulocyte CSF (CI-CSF). The simultaneous addition of plateau levels of IL3 and GM-CSF resulted in an infra-additive augmentation of d7 and d14 CFU-GM-derived clones, whereas IL3 and G-CSF enhanced the number and cellularity predominantly of d14 CFU-GM. In liquid cultures, IL3 induced a greater than 100-fold increase in the number of basophil-mast-like cells and eosinophils and allowed maintenance of these cultures for up to 7 weeks. Human GM-CSF was an almost equally potent, stimulus of eosinophil development but had only a marginal effect on basophilic precursors, whereas G-CSF lacked both activities. Therefore, human IL3 is a multilineage hemopoietic growth factor whose activities appear to encompass and extend beyond those of GM-CSF.

Adult↗
PubMed1988

The response of human marrow colony-forming units-granulocyte and macrophage to inhibition by prostaglandin E and acidic isoferritins is associated with expression of MHC class II antigens and requires the participation of a CD8+ T lymphokine.

The in vitro expression of MHC class II Ag by human bone marrow colony-forming unit-granulocyte and macrophage (CFU-GM) and their proliferative response to negative growth regulators in agar culture are transient and can be modulated in vitro by 24-h suspension culture in the presence of PGE. Analysis of the participation of accessory cells in this phenomenon indicates that the ability of PGE to modulate CFU-GM MHC class II expression, the proportion of CFU-GM in S-phase of the cell cycle and the responsiveness of CFU-GM to inhibition in vitro by two negative growth regulators, acidic isoferritin inhibitory activity and PGE itself, requires the participation of CD8+ T lymphocytes. This effect is mediated by a lymphokine of m.w. 27,000 that we have purified to apparent homogeneity. This lymphokine possesses neither colony stimulatory nor inhibitory activity, is produced by both peripheral blood and bone marrow CD8+ T lymphocytes, as well as the CEM T-ALL cell line, and requires the obligatory presence of PGE for activity.

Adult↗
PubMed1988

Radiosensitivity of NK lytic activities and NK-mediated hematopoietic colony inhibition: effect of activation with IL-2 and blocking of the T-200 molecule.

NK cells are capable of a variety of effector functions including the unprimed lysis of certain tumor cell targets and the nonspecific suppression of hematopoietic colony formation. In this study we have evaluated in parallel the radiosensitivity of lytic and colony inhibitory activity (CIA) by peripheral blood lymphocytes and large granular lymphocytes before and after activation by 72-96 hr of culture in medium containing interleukin 2 (IL-2). Our results show that (1) cells exhibiting CIA and lytic activities have almost identical patterns of radioresistance both before and following activation by IL-2; (2) the amount of preculture irradiation which completely blocks IL-2-stimulated cell proliferation only minimally affects CIA and lytic activities; (3) lysis of K562 and inhibition of CFU-GM are more resistant to preculture irradiation than is the killing of NK insensitive targets; (4) both the CIA and the lytic activities of PBL, but not of LGL, can be increased by 500-1000 rad of gamma-irradiation; and (5) NK lytic activity and CIA both before and following activation by IL-2 are primarily mediated by cells bearing the NKH1A antigen. Evidence that suggests NK cells mediate both the lysis of K562 and the inhibition of myeloid cells by a common mechanism came from experiments which showed that a monoclonal antibody to the T-200 molecule (13.3) could block both activities.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1988

Differential in vitro activation of CD8-CD4+ and CD4-CD8+ T lymphocytes by combinations of anti-CD2 and anti-CD3 antibodies.

Purified peripheral blood T lymphocytes and the CD8-CD4+ and CD4-CD8+ T cell subsets, exhaustively depleted of APC have been studied for their capacity to respond to mAb directed against the CD3-Ti Ag-specific TCR complex and against the CD2 SRBCR. It is demonstrated that high affinity IL-2R can be readily induced by either anti-CD3 and/or anti-CD2 stimulation. However, IL-2 production can be observed only in the CD4+CD8- T cell subset. These results clearly contrast data obtained with purified CD4-CD8+ T cells, which are able to proliferate when the CD3-Ti complex is activated in the presence of APC. The data presented in the present study demonstrate that a simplified model for T cell activation and clonal expansion of the two major T cell subsets involve only the CD3-Ti complex and the CD2 Ag. Under conditions where the activation signals for the T cells are restricted only to the activation of CD3-Ti and CD2, the CD4+CD8- T cells respond with IL-2 production and expression of high affinity IL-2R, whereas the CD4-CD8+ T cell subset depends on exogenous IL-2 provided by the CD4+CD8- cells. These data do not, however, exclude an involvement of other cell-surface signals for regulation and control of T cell activation and T cell effector functions.

Antibodies, Monoclonal↗
PubMed1988

Distinction of partially purified human natural killer cytotoxic factor from recombinant human tumor necrosis factor and recombinant human lymphotoxin.

Natural killer cell cytotoxic factor (NKCF), a cytotoxic factor contributing to human natural killer cell-mediated cytotoxicity, was generated from lymphocyte-conditioned medium using various stimuli. Crude NKCF activity was concentrated, and partially purified by ammonium sulfate precipitation and gel filtration. NKCF activities eluted as two molecular weight peaks, corresponding to Mr 33,000-43,000 (pool I) and approximately Mr 5,000 (pool II). The cytotoxic activity and target specificity of the partially purified NKCFs were found to be different from both recombinant human TNF and recombinant human lymphotoxin. In the NKCF assay, up to 10(6) units/ml of TNF and lymphotoxin had virtually no effect, whereas both NKCFs lysed 22% (range 17-33%) of the NK-sensitive target K562. In contrast, TNF and lymphotoxin were active in a standard assay against the sensitive murine L929 fibroblast cell line in all concentrations tested (10(-1)-10(6) units/ml). In addition, the effect of these cytotoxic factors in a short-term (4-h) chromium-release assay using peripheral blood mononuclear cells as effector cells was tested: only NKCF (pool I), but not TNF, lymphotoxin, or low molecular weight NKCF (pool II), enhanced NK and lymphokine-activated killer cell cytolysis, both against the NK-sensitive target K562 and the NK-resistant melanoma cell line SK-MEL 30. Results were not affected in the presence of neutralizing antibodies against TNF. NKCF could, therefore, be distinguished from TNF and lymphotoxin with respect to their biological activities.

Cell Line↗
PubMed1988

A phase I trial of intraperitoneal recombinant interleukin 2 in patients with ovarian carcinoma.

Seven patients with refractory stage III ovarian carcinoma were treated with escalating doses of human recombinant interleukin 2 (rIL-2) administered via the intraperitoneal (IP) route in an attempt to establish a dose and schedule of rIL-2 suitable for prolonged outpatient IP administration. Three patients went on to receive outpatient maintenance treatment twice weekly for 2-3 months. Doses ranged from 10(5) to 5 x 10(7) U/m2. The dose found most suitable for twice weekly outpatient IP administration was 10(6) U/m2. Dose-limiting toxicities consisted of diarrhea resulting in hypovolemia (5 patients) fever and chills (4 patients), nausea and vomiting (1 patient), mental status changes (2 patients), and azotemia (1 patient). These side effects were not prevented by indomethacin. Significant hypotension was not observed. Pharmacokinetic studies revealed extremely high IP concentrations of IL-2 which persisted for more than 24 hours. After a dose of 10(6) U/m2, the IP concentrations ranged from 670 to 760 U/ml. In one patient in whom concurrent serum concentrations were determined, the IP concentrations were over 100-fold higher than serum levels. After a dose of 10(7) U/m2, the IP concentrations of IL-2 ranged from 8700 to 14000. Concurrent serum levels in one patient revealed IP concentrations over 500-fold higher than serum levels. There were no consistent changes in T cell surface and activation markers on mononuclear cells from peripheral blood in 3 patients tested. Natural killer cell (NK) activity in peripheral blood increased in the three patients in whom it was measured. Four of the 7 patients progressed on treatment; 3 patients remained stable. We conclude that 10(6) U/m2 of rIL-2 is well-tolerated when administered by the IP route and that concentrations of IL-2 well in excess of that required to enhance cell-mediated cytotoxicity in vitro persist in the IP fluid for at least 24 hours.

Adult↗
PubMed1988

Anti-tumor efficacy of interleukin-2-activated killer cells in human neuroblastoma ex vivo.

We studied the ex vivo sensitivity of continuously cultured neuroblastoma cells from 3 different patients towards interleukin-2-induced cell-mediated cytotoxicity. A mean (+/- SD) target cell lysis (4 h 51Cr release) of 49 +/- 11, 46 +/- 8, and 32 +/- 11% in SMS-SAN, LA-N-1, and SK-N-BE2 cell lines, respectively, was achieved when neuroblastoma cells were co-cultured at an effector-to-target (E:T) ratio of 50:1 with peripheral blood mononuclear cells (PBMC) that had been preincubated for 4 days in the presence of recombinant interleukin-2 (rIL-2; 100 U/ml). Under identical conditions, 93 +/- 9% of Daudi cells (a standard target for rIL-2-activated killer cells) were lysed. Preincubation of rIL-2-induced PBMC cultures in the presence of irradiated neuroblastoma targets (LA-N-1, SK-N-BE2) resulted in a significant cytolytic augmentation. At E:T ratios of 50:1 and 10:1, day-4 rIL-2/LA-N-1-stimulated PBMC produced 69 +/- 7 and 41 +/- 11% lysis of LA-N-1 cells, as compared to 46 +/- 8 and 22 +/- (mean +/- SD) 7% lysis by untargeted PBMC that were preincubated with rIL-2 (100 U/ml) in the absence of LA-N-1 target cells (p less than 0.05). Co-incubation of rIL-2-induced PBMC preparations with irradiated LA-N-1 and SK-N-BE2 cells, respectively, did not significantly enhance the cytolytic activity against other neuroblastoma targets and the standard Daudi cell line (p greater than or equal to 0.3).(ABSTRACT TRUNCATED AT 250 WORDS)

Cytotoxicity, Immunologic↗
PubMed1988

Chemotactic activity of recombinant human granulocyte colony-stimulating factor.

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) induced migration across polycarbonate filters of human polymorphonuclear leukocytes (PMN). rhG-CSF was active in inducing PMN migration at concentrations greater than or equal to 10 to 100 U/mL (7 to 70 ng/mL). rhG-CSF did not contain appreciable levels of endotoxin contamination as assessed by Limulus amebocyte assay, and Polymixin B did not affect the chemotactic activity of rhG-CSF. A monoclonal anti-G-CSF antibody blocked the induction of migration by G-CSF, thus establishing that the cytokine was responsible for the activity of the recombinant preparation. Checkerboard analysis was performed by seeding different concentrations of G-CSF above and/or below the filter and revealed that the migratory response to this cytokine was best observed in the presence of a positive concentration gradient between the lower and upper compartments of the chamber, thus indicating an actual chemotactic effect. When different migrating cells were examined, rhG-CSF was inactive on large granular lymphocytes and endothelial cells under conditions in which appropriate reference attractants were active. In contrast, rhG-CSF elicited a chemotactic response in monocytes inhibited by specific antibody. Thus, G-CSF is a chemotactic signal for phagocytes. This cytokine, when produced at inflammatory sites, may contribute to the recruitment of phagocytes from the blood compartment to amplify resistance against certain noxious agents.

Antibodies, Monoclonal↗
PubMed1988

Recombinant human granulocyte-colony stimulating factor: in vivo effects on myelopoiesis in primates.

G-CSF belongs to a family of hematopoietic growth factors, also known as colony stimulating factors. It supports the growth and differentiation of predominantly committed neutrophil precursors and activates the function of peripheral blood neutrophils in vitro. In vivo studies in primates (Cynomolgus monkeys) demonstrated that G-CSF is a potent myeloid growth and differentiation factor causing a dose-dependent increase predominantly in the peripheral blood neutrophils. To assess the effects of G-CSF in chemotherapy induced cytopenias, we administered G-CSF to monkeys that had been treated with cyclophosphamide (60 mg/kg/dx2), or repeated cycles of busulfan (4, 6 or 10 mg/kg/dx3). In both, cyclophosphamide and busulfan induced myelosuppression, G-CSF in doses between 10 and 30 micrograms/kg/d was able to significantly shorten the time of neutropenia. In addition, monkeys were treated with G-CSF (50 or 100 micrograms/kg/d) for one month post autologous bone marrow transplantation following total body irradiation. The time of neutropenia (less than 1,000 neutrophils/mm3) was shorter in the G-CSF treated monkeys (10 days in the 100 micrograms/kg/d treated monkey) compared to two controls (21 days). The post transplant absolute neutrophil count of approximately 30,000/mm3 could be maintained for the entire period of G-CSF exposure.

Animals↗
PubMed1988

Phase I trial of recombinant interleukin-2 and cyclophosphamide: augmentation of cellular immunity and T-cell mitogenic response with long-term administration of rIL-2.

Long-term subcutaneous (s.c.) administration of recombinant Interleukin-2 (rIL-2) was evaluated in 18 patients with advanced malignancy who received escalating doses of rIL-2 (1.0-9.8 X 10(6) U/m2) s.c. five times per week for a median of 38 days (range 5-228 days). Prior to the s.c. phase of the study, 24 patients received low doses (50 or 350 mg/m2) of cyclophosphamide (CPM) i.v. on day 1 followed by 10 doses (days 5-9 and 12-16) of rIL-2 (1 X 10(6) U/m2) given by 6 h i.v. infusion. There were no major antitumor effects. Toxicity was not clearly dose-related, with pain and induration at s.c. injection sites, fatigue, malaise, and palpitations most often observed. Pretreatment baseline ranges (PBR), which are 95% prediction intervals that reflect both intra- and interpatient variability, were calculated for nine hematologic and immunologic variables derived from 21 of the 24 patients. While pretreatment with CPM had no significant effect on these variables during the i.v. phase of the study as compared to a prior study using an identical rIL-2 i.v. infusion schedule, prolonged administration of s.c. rIL-2 was associated with (a) enhancement of natural killer (NK) cytotoxicity against K562 in 13 of 21 patients (p less than 0.00001), (b) increases in cytotoxicity against K562 (15 patients) and against Daudi (9 patients) in the presence of 10 U/ml of rIL-2 (p = 0.007), (c) increases in the proliferative response in vitro to OKT3 and rIL-2 in 12 patients (p less than 0.00001), (d) lymphocytosis with increase in percentage of Tac (13 patients, p less than 0.00001), T8 (11 patients, p = 0.0005), and T9 (8 patients, p = 0.021) expression, and (e) eosinophilia. While initial rises in some of these variables occurred during the i.v. phase of the study, maximum increases for all variables except T9 positivity occurred during prolonged s.c. therapy. Nine of 10 patients studied while on therapy greater than 50 days had anti-rIL-2 antibodies in an enzyme-linked immunosorbent assay; in only one case was the antibody neutralizing. This study demonstrates that significant enhancement of cytotoxicity against both NK-sensitive and -resistant targets and improvements in T-cell mitogenic response occur with long-term administration of rIL-2. Further evaluation of long-term administration of tolerable doses of rIL-2 is warranted.

Antibodies, Monoclonal↗