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K Welte

Publications and source records attributed to K Welte.

At least 145 records · Page 8Linked to original sources
PubMed1987

Antigen-induced human interferon-gamma production. Differential dependence on interleukin 2 and its receptor.

Once stimulated with Toxoplasma gondii or cytomegalovirus (CMV) antigens, peripheral blood mononuclear cells from healthy seropositive donors secrete comparable levels of interferon-gamma (IFN-gamma). Both antigens also stimulated specific production of interleukin 2 (IL-2), a lymphokine believed to be important in IFN-gamma generation. T. gondii antigen, however, induced ninefold more IL-2 than did CMV antigen suggesting different mechanisms for antigen-stimulated IFN-gamma production. Therefore, we examined for both antigens 1) the cellular sources of IL-2 and IFN-gamma, 2) the kinetics of IL-2 production and IL-2 receptor (IL-2R) expression, and 3) the effect of antibodies to IL-2 and IL-2R on IFN-gamma secretion. For both antigens, IL-2 and IFN-gamma secretion was T4+ cell-dependent. T. gondii antigen induced high levels of IL-2 at 24 hr which increased further at 48 hr, and IFN-gamma production was strongly inhibited by antibodies to both IL-2 (90 +/- 2%) and IL-2R (80 +/- 5%). In contrast, CMV antigen stimulated low levels of IL-2 at 24 hr which declined still further by 48 hr, and CMV-stimulated IFN-gamma generation was appreciably less well inhibited by antibodies to IL-2 (47 +/- 2%) and IL-2R (31 +/- 8%). These results suggest the possibility of two mechanisms for antigen-induced IFN-gamma production--one primarily dependent on and the other largely independent of IL-2 and its receptor. Both mechanisms, however, require the activity of sensitized T4+ cells.

Animals↗
PubMed1987

Stimulation of T lymphocyte proliferation by monoclonal antibodies against GD3 ganglioside.

Cell-surface gangliosides are presumed to play a role in cell growth and differentiation. With the use of monoclonal antibodies directed against GD3, a disialoganglioside expressed predominantly by cells of neuroectodermal origin, we have found that GD3 is expressed by a subpopulation of cells of the immune system including: 1) fetal thymocytes in subcortical regions and near vessels, 2) lymph node lymphocytes in interfollicular areas and near vessels, and 3) a small subset of T cells in the peripheral blood. Mouse monoclonal antibodies (two IgGs, one IgM, and F(ab')2 fragments) reacting with GD3 were found to stimulate proliferation of T cells derived from peripheral blood. Proliferation of T cells was observed even in cultures depleted of macrophages, suggesting that activation by anti-GD3 was not dependent on the presence of accessory cells. T cell proliferation was maximum between days 5 and 7 of stimulation and was preceded by expression of interleukin 2 receptors. No stimulation was observed with control antibodies of the identical isotype or with monoclonal antibodies recognizing the gangliosides GD2 or GM2. During stimulation by anti-GD3 monoclonal antibodies, there was an expansion of the GD3+ pool of T cells, but depletion of GD3+ T cells prior to stimulation abrogated the response. Proliferation induced by binding to GD3 could be augmented by exogenous interleukin 2 and phytohemagglutinin. Anti-CD3 (T3) monoclonal antibodies had little or no effect. These results demonstrate that binding to GD3 on the surface of T cells can elicit signals for T cell proliferation.

Antibodies, Monoclonal↗
PubMed1987

Purification and biochemical characterization of a human autocrine growth factor produced by Epstein-Barr virus-transformed B cells.

Autocrine growth factor for Epstein-Barr virus-transformed human B cells (aBGF), a protein that is constitutively produced by the human EBV-transformed B cell line 5/2, has been purified from serum-free conditioned medium. The purification involved sequential ammonium sulfate precipitation, ion exchange chromatography, gel filtration, and reversed-phase high performance liquid chromatography. The purified protein has a m.w. of 16,000 in NaDodSO4/polyacrylamide gel electrophoresis and an isoelectric point between 7.0 and 8.0. The relative molecular mass 16,000 form exists in equilibrium with dimeric and tetrameric forms. aBGF supports the growth of EBV-transformed B cells, which have been deprived of their own conditioned medium. The purified aBGF is fully effective at 0.5 ng/ml and has no interleukin 1 activity in the lymphocyte activation factor assay. Because several randomly selected lines of EBV-transformed cells and one EBV-negative lymphoma cell line both produce aBGF activity and show growth dependency on aBGF and because stimulation of normal B cells with anti-immunoglobulin M is increased by aBGF, we propose that aBGF has general significance for growth control of human B cells.

B-Lymphocytes↗
PubMed1987

Recombinant human granulocyte colony-stimulating factor. Effects on hematopoiesis in normal and cyclophosphamide-treated primates.

We examined the in vivo effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in primates (cynomolgus monkeys) treated with subcutaneous doses of rhG-CSF for 14-28 d. A dose-dependent increase in the peripheral white blood cells (WBC) was seen, reaching a plateau after 1 wk of rhG-CSF treatment. The elevation of WBC was due to an increase in the absolute neutrophil count. These results demonstrate that rhG-CSF is a potent granulopoietic growth and differentiation factor in vivo. In cyclophosphamide (CY)-induced myelosuppression, rhG-CSF was able to shorten the time period of WBC recovery in two treated monkeys to 1 wk, as compared to more than 4 wk for the control monkey. Its ability to significantly shorten the period of chemotherapy-induced bone marrow hypoplasia may allow clinicians to increase the frequency or dosage of chemotherapeutic agents. In addition, the increase in absolute numbers of functionally active neutrophils may have a profound effect in the rate and severity of neutropenia-related sepsis. Furthermore, the activities reported here indicate a potential role for rhG-CSF in the treatment of patients with myelodysplastic syndrome, congenital agranulocytosis, radiation-induced myelosuppression, and bone marrow transplantation.

Animals↗
PubMed1987

Experimental visceral leishmaniasis: production of interleukin 2 and interferon-gamma, tissue immune reaction, and response to treatment with interleukin 2 and interferon-gamma.

During the first 2 to 4 weeks of progressive visceral infection with the intracellular protozoan, Leishmania donovani, spleen cells from BALB/c mice failed in response to leishmanial antigen to produce either of the activating T cell-derived lymphokines, interleukin 2 (IL 2) or gamma-interferon (IFN-gamma). Four weeks after infection, however, antigen-induced IL 2 and IFN-gamma secretion emerged and coincided with the onset of control over parasite replication and the subsequent killing of greater than 80% of intrahepatic L. donovani. The development of this immunosecretory activity correlated with the hepatic tissue response at the site of parasitized Kupffer cells. This response progressed from Kupffer cell fusion (week 1) to fusion plus a mononuclear cell infiltrate (week 2) to well-organized granuloma formation (weeks 4 to 8). In contrast, T cell-deficient nude BALB/c mice exerted no control over L. donovani, their spleen cells failed to generate antigen-induced IFN-gamma, and at 4 weeks, their livers were devoid of any tissue reaction. Since spleen cells from 2-week infected normal mice did not produce antigen-stimulated IL 2 or IFN-gamma, these mice were treated with recombinant (r) lymphokines. Various protocols using both high and low dose human rIL 2 had no antileishmanial effect. Hepatic parasite replication was completely halted, however, by macrophage-activating doses of murine rIFN-gamma. These results reemphasize that an intact T cell-dependent response is required for successful defense against L. donovani, indicate that this immune response can be measured at both the cellular (secretory) and tissue levels, and confirm that IFN-gamma can exert an antileishmanial effect in vivo.

Animals↗
PubMed1987

T-cell activation defect in common variable immunodeficiency: restoration by phorbol myristate acetate (PMA) or allogeneic macrophages.

Common variable immunodeficiency (CVI) represents a group of familial and sporadic diseases characterized by a range of B-cell, T-cell, and macrophage defects. A defect in T-cell activation, involving reduced proliferation and IL-2 production after stimulation with OKT3 antibody, has been described previously. In the present study we found that these defects could be corrected in vitro by adding phorbol myristate acetate (PMA) to OKT3-stimulated peripheral blood mononuclear cells (PBMC) of 14 patients with CVI. PBMC of 6 out of 7 patients with CVI studied also exhibited a profound defect in IL-2 receptor expression when incubated with OKT3 antibody. IL-2 receptor expression after stimulation with PMA alone was normal, indicating that the OKT3- but not the PMA-induced pathway of IL-2 receptor expression was defective. On the RNA level, the genes for IL-2 and IL-2 receptor were expressed after stimulation with OKT3 antibody. IL-2 and IL-2 receptor gene expression were normal, indicating a possible post-transcriptional defect. To investigate whether the defect in T-cell activation was at the macrophage or the T-cell level, we prepared adherent cells and monocyte-depleted T cells (E+) from 3 patients with CVI and from normal blood donors. Incubating CVI E+ cells with normal adherent cells resulted in normal proliferation and IL-2 production in the presence of OKT3, whereas incubation of normal E+ cells with adherent cells from patients with CVI under the same conditions showed reduced IL-2 production and proliferation, suggesting the macrophage as the origin of the failure in T-cell activation in the patients with CVI studied. Inhibition by macrophage-secreted prostaglandins was excluded by failure to correct the IL-2 production and proliferation defects in the presence of indomethacin.

Adult↗
PubMed1987

Analysis of prostaglandin E2 effect on T lymphocyte activation. Abrogation of prostaglandin E2 inhibitory effect by the tumor promotor 12.0 tetradecanoyl phorbol-13 acetate.

We have investigated the inhibitory potential of prostaglandin E2 (PGE2) with respect to intracellular messengers implicated in the signaling system of T-lymphocyte activation pathway. Using the fluorescent indicator Quin 2, it is demonstrated that PGE2 inhibits the increase in cytosolic-free calcium concentration [Ca2+]i. Reconstitution of calcium mobilization in the presence of PGE2 by the calcium ionophore A23187 results in a partial restoration of both interleukin 2 (IL2) production and cell proliferation and has no effect on the inhibition of transferrin receptor expression. In contrast, the treatment of cell cultures with the tumor promotor 12.0 tetra decanoyl phorbol-13-acetate (TPA) abrogates the suppressor activity of PGE2. When T lymphocyte stimulation is provided by the combination of A23187 and TPA, the PGE2 inhibitory effect does not occur. These data also indicate that the down regulation of transferrin receptor by PGE2 is proximal to protein kinase C activation and is not associated with decreased expression of the functional IL2 receptor.

Calcimycin↗
PubMed1987

Interleukin-2- and mitogen-activated NK-like killer cells from highly purified human peripheral blood T cell (CD3+ N901-) cultures.

In this study, highly purified (HP) CD3-positive N901-negative T lymphocytes could be induced to become natural killer (NK)-like in culture in the presence of recombinant interleukin-2 (rIL-2) and phytohemagglutinin (PHA). Thus, purified CD3+ N901- T cells from fresh human peripheral blood were obtained by negative selection using an indirect panning technique. To ensure that T lymphocyte fractions were completely devoid of any detectable NK cells, two additional purification procedures were employed: incubation of post-pan T cells with the NK-cytotoxic lysomotropic agent L-leucinemethylester, and complement-mediated lysis using the NK cell specific NKH1a monoclonal antibody. Purity of CD3+ N901- cells could be confirmed by surface marker analysis, whereby two NK-associated antigens, N901 and H-25, were undetectable, while 94 +/- 1% of cells expressed the CD3 (Leu-4) antigen. On functional analysis, fresh HP CD3+ N901- cells exhibited no cytotoxic activity against the standard NK target K562. When HP NK-depleted T lymphocytes were cultured for 7 days in the presence of rIL-2 (100 U/ml), neither surface antigen expression nor cytotoxic activity against K562 changed significantly. However, significant cytotoxicity against K562 [18 +/- 5% specific lysis at 25:1 effector:target (E/T) ratio] could be induced when HP CD3+ N901- cells were grown for 7 days in the presence of rIL-2 and PHA (0.5% v/v). Concomitantly, antigens N901 and H-25 were found to be coexpressed on a minor proportion (22 +/- 16 and 22 +/- 6%, respectively) of CD3+ (88 +/- 2% on day 7) cells. Four-week long-term culture of HP NK-depleted T cells in the presence of rIL-2 and PHA yielded a continuous increase in cytotoxicity against K562 cells (0 up to 46% specific lysis at 25:1 E/T ratio). Of particular interest was the emergence of cytotoxicity against the NK-resistant Daudi cell target (15 +/- 8% specific lysis at 25:1 E/T ratio on day 21). Expression of antigens N901 and H-25 as well as CD3 remained essentially unchanged in long-term culture. In sorting experiments, the H-25+ cell fraction was significantly enriched for cytotoxicity against K562, when compared to both H-25- and unseparated cell fractions. In summary, our results suggest that a proportion of HP CD3+ N901- T lymphocytes may give rise to cells that exhibit NK-like functional and phenotypic properties.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1987

Interleukin 2-activated killer cells in patients following transplants of soybean lectin-separated and E rosette-depleted bone marrow.

During the early period following bone marrow transplantation before the immune system has reached full functional maturity, unprimed, nonspecific lytic systems may play a critical role as antiviral or antitumor effectors. The reconstitution of cells with this potential is of particular importance in recipients of bone marrow that has been depleted of mature T lymphocytes to prevent graft v host disease (GVHD). We examined the recovery of natural killer (NK) cells and interleukin 2 (IL 2)-augmented lymphokine-activated killer cells (LAK) in 48 patients at various intervals following transplantation of bone marrow depleted of mature cellular elements by treatment with soybean agglutinin and sheep RBCs (SBA-E- BMT). We found normal levels of both NK and LAK activity as early as 3 weeks following SBA-E- BMT. When compared with cells from controls, NK and LAK precursors from transplant recipients appeared to be activated in vivo in that freshly isolated peripheral blood mononuclear cells (PBMCs) from patients had an elevated cytolytic activity toward NK-insensitive targets and a more rapid response to activation by IL 2. In patients as well as controls, both LAK precursors and LAK effectors lacked antigens present on mature T lymphocytes (CD3, CD4, or CD8) but expressed antigens present on NK cells (CD2, CD16, and NKH1A). The LAK cells did not lyse either donor or host peripheral blood T cell targets. The activity of NK effectors but not LAK precursors survived the in vivo total body irradiation used for pretransplant conditioning in three patients studied. LAK precursors could be demonstrated as early as 18 days following transplant at a time when the bone marrow contained primarily donor-derived cells. Little or no LAK activity could be generated from cells of the SBA-E- BM graft itself, suggesting that LAK precursors differentiate rapidly from more primitive progenitors in the marrow graft. Thus, our data indicate that the NK and LAK lytic systems are among the earliest activities to recover during immune reconstitution following T cell-depleted BMTs.

Bone Marrow Cells↗
PubMed1987

Interleukin-2 production and response to interleukin-2 by peripheral blood mononuclear cells from patients after bone marrow transplantation: II. Patients receiving soybean lectin-separated and T cell-depleted bone marrow.

The ability of peripheral blood mononuclear cells (PBMC) to produce and respond to interleukin-2 (IL-2) was evaluated in 50 recipients of HLA-identical bone marrow (BM) depleted of mature T cells by soybean agglutination and E rosetting (SBA-E-BM). In contrast to our previous findings in recipients of unfractionated marrow, during weeks 3 to 7 post-SBA-E-BM transplantation (BMT), PBMC from the majority of patients spontaneously released IL-2 into the culture medium. This IL-2 was not produced by Leu-11+ natural killer cells, which were found to be predominant in the circulation at this time, but by T11+, T3+, Ia antigen-bearing T cells. The IL-2 production could be enhanced by coculture with host PBMC frozen before transplant but not by stimulation with mitogenic amounts of OKT3 antibody, thus suggesting an in vivo activation of donor T cells or their precursors by host tissue. Spontaneous IL-2 production was inversely proportional to the number of circulating peripheral blood lymphocytes and ceased after 7 to 8 weeks post-SBA-E-BMT in most of the patients. In patients whose cells had ceased to produce IL-2 spontaneously or never produced this cytokine, neither coculture with host cells nor stimulation with OKT3 antibody thereafter induced IL-2 release through the first year posttransplant. Proliferative responses to exogenous IL-2 after stimulation with OKT3 antibody remained abnormal for up to 6 months post-SBA-E-BMT, unlike the responses of PBMC from recipients of conventional BM, which responded normally by 1 month post-BMT. However, the upregulation of IL-2 receptor expression by exogenous IL-2 was found to be comparable to normal controls when tested as early as 3 weeks post-SBA-E-BMT. Therefore, the immunologic recovery of proliferative responses to IL-2 and the appearance of cells regulating in vivo activation of T cells appear to be more delayed in patients receiving T cell-depleted BMT. Similar to patients receiving conventional BMT, however, the ability to produce IL-2 after mitogenic stimulation remains depressed for up to 1 year after transplantation.

Adult↗
PubMed1987

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

The results presented in this paper demonstrate that recombinant human granulocyte-colony stimulating factor (rhG-CSF) is a potent myelopoietic growth and differentiation factor in vivo. RhG-CSF was able to shorten the time period of neutrophil recovery in both cyclophosphamide (CY)-induced myelosuppression and following bone marrow transplantation (BMT) in primates. Its ability to significantly shorten the period of chemotherapy-induced bone marrow hypoplasia may allow clinicians to increase the frequency or dosage of chemotherapeutic agents. In addition, the increase in absolute numbers of functionally active neutrophils may have a profound effect on the rate and severity of neutropenia-related sepsis. Furthermore, the activities reported here indicate a potential role for rhG-CSF in the treatment of patients with myelodysplastic syndrome, congenital agranulocytosis, radiation-induced myelosuppression, and after bone marrow transplantation.

Animals↗
PubMed1987

Activities of four purified growth factors on highly enriched human hematopoietic progenitor cells.

The activities of four purified human growth factors: biosynthetic (recombinant) granulocyte-macrophage colony-stimulating factor (GM-CSF); recombinant erythroid-potentiating activity (EPA); natural and recombinant pluripoietin (Ppo); and natural pluripoietin alpha (Ppo alpha), were compared on the growth of hematopoietic colonies from enriched populations of human marrow and blood progenitor cells. Conditioned medium from the Mo T cell line (MoCM) was used as a standard positive control. We found that activities of GM-CSF and Ppo alpha on the growth of hematopoietic colonies were indistinguishable; Ppo alpha is now believed to be identical to GM-CSF. Both factors were able to promote the growth of colonies derived from subpopulations of CFU-GM, BFU-E, and CFU-GEM. Colonies derived from CFU-GM and CFU-GEM in cultures stimulated by GM-CSF and Ppo alpha were much smaller than in cultures stimulated by MoCM. In contrast to previous reports in which less highly enriched progenitors were used as target cells, Ppo had no detectable activity on the growth of colonies derived from BFU-E or CFU-GEM but promoted the growth of a subpopulation of CFU-GM derived colonies. Ppo is now recognized to be identical to G-CSF. The GM colonies in cultures stimulated by G-CSF (Ppo) were much smaller than in cultures stimulated by MoCM. EPA had no detectable activity on either the size or number of colonies derived from CFU-GM, BFU-E, or CFU-GEM. Results from experiments using target cell populations of marrow fractions separated by velocity sedimentation and marrow populations following freezing suggested that GM-CSF (Ppo alpha) and G-CSF (Ppo) primarily affect the growth of relatively mature subpopulations of progenitor cells. It is clear from these results that additional factor(s) are present in MoCM that are necessary to stimulate CFU-GM, BFU-E, and CFU-GEM maximally in vitro.

Bone Marrow↗