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D von Steldern

Publications and source records attributed to D von Steldern.

12 recordsLinked to original sources
PubMed1988

Increased helper cell activity of NZB mice against H-2-identical allogeneic cells.

The T cells of NZB mice become hyperreactive after stimulation with minor histocompatibility (MIH) antigens. This hyperreactivity has previously been demonstrated only for cytotoxic T cells of NZB, although there was some evidence for an increase of their T-helper cell activity facilitating the response. Here we report a quantitative analysis of T-cell help and help of T-cell subpopulations against autologous, MIH, and H-2 antigens in a limiting dilution assay. After stimulation of NZB T cells with autologous and H-2 antigens, the T-helper cell frequencies did not differ from that of normal mice. After stimulation with MIH antigens however, Lyt 1+2+ T-cells of NZB showed a higher response than those of BALB/c origin. The same difference was seen after prestimulation with ConA or the specific antigen. This demonstrates that NZB-helper cells are more easily activated by weak antigenic differences, and it is possible that this contributes to the prevalence of autoimmune disease in this strain.

Animals↗
PubMed1986

Lymphocyte subpopulations in solvent-exposed workers.

To estimate the cellular immune response of workers highly exposed to mixtures of organic solvents, subpopulations of peripheral blood lymphocytes (PBLs) were analyzed. For this, the PBLs of nine floorers (aged 25-58 years, exposure time 8-35 years) were subsequently labelled with monoclonal antibodies OKT4, OKT8, OKT11, anti-Leu 7 and anti-Leu 12. Analysis was made by a FACS IV cell sorter (Becton-Dickinson, USA). The control group consisted of matched pairs of healthy donors. In the exposed group we found a decrease in the OKT11 (all) T cell fraction, a decrease in the OKT4 helper cells, an increase in the anti-Leu 7 positive cells, mostly natural killer cells, an important increase in anti-Leu 12 labelled T cells, i.e., human B-lymphocytes, and no differences in the OKT8 suppressor cells. Total fluorescence intensity profiles between the exposed and the unexposed group did not differ, i.e., the marker density on the cell surfaces remained unchanged. Similar changes in lymphocyte subpopulations are found in states of immunodeficiency and immunogenetic forms of aplastic anemia, a disease whose etiological relationship may be due to long-term exposure to organic solvents.

Adult↗
PubMed1986

Regulation of interleukin 2 receptor expression by interleukin 2.

The regulatory influence of Interleukin 2 (IL-2) on the expression of IL-2 receptors (IL-2R) was studied using long-term cultured T-cell lines and recombinant IL-2 (r-IL-2). Three T-cell lines with different growth requirements were used as model systems: insulin-specific BK-BI-1.2 cells express IL-2R transiently after antigenic restimulation, ovalbumin-reactive BK-OVA-1R cells express IL-2R permanently, and BK-BI-2.6.C6 cells bear IL-2R constitutively but do not exhibit antigen reactivity. All three T-cell lines exhibited the property of increased IL-2R expression in the presence of r-IL-2, as tested by cytofluorometry employing monoclonal antibody AMT-13 directed at the murine IL-2R. IL-2R density was influenced selectively by r-IL-2, because the level of Thy-1.2 molecules was similar in the presence and absence of r-IL-2. With BK-BI-2.6.C6 cells, r-IL-2 was shown to upregulate high-affinity receptors. Since BK-BI-2.6.C6 and BK-OVA-1R cells were grown in the absence of feeder cells, these data show that r-IL-2 can regulate the expression of its own receptor without the participation of monokines. Results obtained with the T-cell line BK-BI-1.2, representing insulin-specific T cells with transient IL-2R expression, show that the presence of r-IL-2 did not prevent a decline in IL-2R density occurring on day 5 after antigenic stimulus. This indicates that additional mechanisms besides antigen- and IL-2-induced IL-2R upregulation are operative in controlling IL-2R density on the cell surface.

Animals↗
PubMed1985

Postnatal development of functional T cell subsets in the mouse: a frequency analysis of mitogen reactive precursors of proliferating, of cytotoxic and of IL 2 producing T cells.

In order to study the postnatal development of functional T cell subsets in the mouse, a mitogen-driven limiting dilution culture system was used for a precursor frequency analysis of proliferating, of cytolytic and of IL 2-producing T cells, respectively, present in spleen and thymus of mice from neonatal to adult age. In adult mice, the majority (up to 100%) of splenic T cells was capable to respond to Concanavalin A. In contrast, an up to tenfold lower frequency of mitogen-reactive precursors was found within positively selected Thy-1+ spleen cells of neonatal mice. Within this fraction of Con A reactive neonatal T cells, there was an apparent imbalance in the CTLp/PTLp ratio within the first to second week after birth. Accordingly, significant numbers of immunocompetent precursors of HTLp were detected in the spleen shortly after birth, while the vast majority of CTLp developed later on. This differential development of CTLp and PTLp was not seen with thymocytes of the same mice, where from the age of two to three days on up to the adult age the frequency of both CTLp and PTLp remained largely unchanged. Analysis of the Lyt-antigen expression, in addition, revealed phenotypical differences between neonatal and adult Thy-1+ spleen cells, such that Lyt-2 antigen density but not the proportion of Lyt-2 positive T cells, was considerably lower in newborn mice. An age related increase in both Lyt-2 antigen density and CTLp frequency was parallelled by the rapid increase in the total number of splenic T cells during the second and third postnatal week, reaching 60-70% of adult values. At this time, a normalisation of the CTLp/PTLp ratio at approximately 0.4 had occurred.

Age Factors↗
PubMed1985

In vitro maturation of B cells in chronic lymphocytic leukemia. I. Synergistic action of phorbol ester and interleukin 2 in the induction of Tac antigen expression and interleukin 2 responsiveness in leukemic B cells.

Recent evidence indicates that interleukin 2 (IL 2), formerly thought to serve as growth factor exclusively for activated T cells, is directly involved in human B cell differentiation. We have investigated the role of IL 2 and IL 2 receptors (as defined by monoclonal anti-Tac antibody) in the phorbol ester-induced in vitro maturation of leukemic B cells from patients with chronic lymphocytic leukemia (CLL). Peripheral blood lymphocytes from B cells from CLL patients with high (greater than 10(5)/microliters) white blood cell counts were depleted of residual T lymphocytes and low-density cells (primarily macrophages) by consecutive steps of E rosetting, complement-mediated lysis of OKT3+ and OKT4+ cells, and Percoll density gradient centrifugation. No OKT3+ T cells were detectable in these cell populations before or after culture. When incubated for 3 days with phorbol ester plus recombinant human IL 2 (rIL 2), 12 to 57% of highly purified B cells from four of five tested patients expressed Tac antigen. Both phorbol ester and rIL 2 were required for maximal Tac antigen expression. Functional studies revealed that phorbol ester-activated (but not resting) CLL B cells responded to rIL 2 with [3H]thymidine incorporation and with enhanced secretion of IgM. Tac+ B cells were isolated in two cases on a fluorescence-activated cell sorter. In one patient, stimulation of Tac+ B cells with rIL 2 resulted in enhanced [3H]thymidine incorporation but no change in IgM secretion, as compared with Tac- B cells; in the second patient, stimulation of Tac+ B cells with rIL 2 did not result in [3H]thymidine uptake, but did result in significant IgM secretion. These findings indicate that certain leukemic B lymphocytes can be induced to express IL 2 receptors and respond to IL 2. The use of resting clonal B cell populations arrested at distinct stages of differentiation may help to better define the stage(s) at which IL 2 acts directly on B cells to induce proliferation and/or terminal differentiation.

Antibodies, Monoclonal↗
PubMed1985

Cell surface antigens on the guinea-pig macrophage: identification by monoclonal antibodies and association with the activation state.

Ten monoclonal antibodies (moAb) directed against cell surface antigens of guinea-pig monocytes and macrophages (mph) were produced and characterized. The corresponding antigens are not present on granulocytes, T lymphocytes, an Ia-positive B-cell line or other haematopoietic cells. In binding or cytotoxicity assays, the moAb demonstrated characteristics patterns of reactivity, with mph being in different stages of differentiation or activation. Three moAb (342, 322, 249) recognized 'lineage antigens' (i.e. antigens continuously expressed during maturation of monocytes to mph and after stimulation or activation of the cells). MoAb 342 possibly defines a major cell surface determinant, being present on 90% of mph. The antigens detected by moAb 305, 320, 321 and 344 characterize mature mph. They were not expressed on monocytes, but were expressed on the majority of resident, elicited or activated peritoneal mph. MoAb 253, 310 or 257 defined discrete subpopulations of elicited and--with the exception of moAb 257--activated mph. The corresponding antigens were not present on monocytes or resident mph, but appeared on the cell surface during in vivo or in vitro stimulation of the cells. There was no indication of a contribution of the moAb-defined antigens to the presentation of antigen, mitogen or alloantigen by the mph to T cells. The functional significance of the antigens thus remains to be elucidated. Our studies indicate that cells committed to the monocyte/mph lineage share a family of differentiation antigens, distinguishing them from other cell lines. The moAb provide useful tools for further investigation of the activation of mph and allow the rapid detection of mph in different tissues.

Animals↗
PubMed1984

Equal distribution of T-lymphocyte subpopulations in thymus and spleen cells of NZB and BALB/c mice.

NZB mice develop an autoimmune disease of unknown etiology. Since the detection of immunoregulatory T-cells it has been speculated that disbalances of these cells may be important in the course of the NZB disease. By utilization of monoclonal antibody defining immunoregulatory Lyt subsets and a FACS IV system we investigated whether differences in the number and/or marker densities of given subsets exist between NZB and the normal reference strain BALB/c. Newborn animals and animals up to 60 weeks of age were tested. No significant difference in the percentages nor in the marker densities of theta+, Lyt 1+, and Lyt 2+ cells was observed at any age or sex, neither in spleen nor in thymus. It is concluded the autoimmune disease of NZB is not influenced by the parameters investigated.

Aging↗
PubMed1984

Perpetual proliferation of LYT-1 cells requires repetitive signals for IL-2 receptor induction by antigen-presenting cells.

T cell lines with specificity for bovine insulin and ovalbumin were maintained by serial stimulation with antigen presented on irradiated syngeneic spleen cells, alternating 3 days later with subculture in IL-2 containing medium (CM). When the cultures were repetitively split in CM, with concomitant dilution of antigen-presenting cells, a gradual loss of proliferative capacity of the cells in the presence of CM was observed. Absorption studies revealed a 20-fold reduction of IL-2 receptors on the surface of T blasts assayed 12 days after antigenic stimulation as compared with day 5 blasts. This decrement in the number of IL-2 acceptor sites reflected an actual decrease in cell surface density of IL-2 receptors. Restimulation of the T blasts with antigen and spleen cells induced both a substantial increase in IL-2 receptor density and responsiveness to CM. Furthermore, the permanent presence of antigen and spleen cells during splitting of the T blasts in CM prevented the loss of responsiveness to IL-2. As an interpretation we propose that the Lyt-1 cells studied here clear their IL-2 receptors from the cell surface after interaction with IL-2. Thus, each new round of replication of the daughter cells would be dependent on induction of IL-2 receptors by activating signals provided by antigen/Ia structures on accessory cells as well as possibly accessory cell products such as IL-1, rendering Lyt-1 cells sensitive to regulatory influences.

Absorption↗
PubMed1984

Interleukin 2 receptors on an insulin-specific T cell line: dynamics of receptor expression.

Long-term cultured T blasts with specificity for bovine insulin (BK-BI-1.2), which cease growing in IL 2 supplemented medium and require periodic antigenic challenge to resume proliferation, were selected as a model system to analyze the regulation of the growth of activated T cells. The use of AMT-13, a monoclonal antibody (mAb) directed at the murine IL 2 receptor, in indirect binding experiments and in FACS analysis allowed us to examine the time-dependent expression of IL 2 receptors on BK-BI-1.2 blasts after antigenic stimulation. The data reveal a transitory expression of IL 2 receptors, attaining maximal levels on day 2 after antigenic induction and having declined to low levels by day 6. mAb 10-2.16, reactive with I-Ak, did not inhibit T cell-proliferative capacity when the cells were subcultured in IL 2. This result suggests that, once induced to maximal levels by antigen, the transitory expression of IL 2 receptors on the descendent cells is not dependent on the continual presence of antigen-presenting cells. Thus, the progressive loss of IL 2 receptors apparently is not due to a mechanism operating by clearance of receptors from the cell surface on completion of each cell cycle, leading to dependency of the descendent cells on repeated contact with antigen for renewed receptor expression. The disappearance of IL 2 receptors from the surface of antigen-stimulated T cells might provide a basis for the control of immunologic specificity in vivo.

Animals↗
PubMed1984

Expression of Ia antigens on macrophages is reduced after stimulation with homologous C3b.

The complement cleavage product C3b was examined for its ability to influence the expression of Ia antigens on macrophages. Monoclonal anti-Ia antibodies were applied for quantitation of Ia antigens by using FACS analysis. Albumin-elicited guinea pig peritoneal macrophages were cultured for 48 hr in the presence of C3b. C3b at final concentrations varying from 10 to 80 micrograms/ml reduced the proportion of Ia-positive macrophages from 87 to 25%. The C3b-stimulated loss of Ia antigens from the macrophage surface was mediated by metabolites of the cyclooxygenase pathway as shown by the inhibitory effect of indomethacin. Exposure of macrophages to C3b for 5 min was sufficient to induce Ia reduction, seen after subsequent 48-hr incubation. C3b generated in vivo in the course of inflammatory reactions might therefore influence the interaction of immunocompetent cells by modulating macrophage Ia expression.

Animals↗
PubMed1983

Identification and characterization of gp TFA-1, a guinea pig T cell surface antigen associated with T cell function.

Monoclonal antibodies (Ab) were produced that specifically recognized guinea pig T cells. FACS analysis revealed that Ab 188 bound to the majority of peripheral T lymphocytes of strain 2 and strain 13 guinea pigs and to a minor population of thymocytes. It failed to react with the Ia-bearing guinea pig B cell leukemia line EN-L2C, with macrophages, bone marrow cells, erythrocytes, or thrombocytes. Treatment of T cells with Ab 188 and complement prevented T cell activation. Culturing primed T cells with antigen- or mitogen-pulsed syngeneic or with allogeneic macrophages in the continuous presence of Ab 188 produced a marked, dose-dependent inhibition of T cell proliferation. The antigen defined by Ab 188 was therefore designated guinea pig T lymphocyte function-associated antigen-1, gp TFA-1. The magnitude of inhibition by Ab 188 varied between 65 and 85% whereas three other antibodies to guinea pig T cells had no inhibitory effect on T cell proliferation. Time course experiments revealed that gp TFA-1 is critically involved in an early phase of T cell activation. Maximal inhibition was achieved only if the antibody was present from the beginning of the cell culture; the addition of antibody after 24 hr of culture no longer had an inhibitory effect. Ab 188 did not induce T cell mitogenesis. Two-dimensional analysis (one-dimensional, IEF; two-dimensional, SDS-PAGE) of immunoprecipitates obtained from NP40 lysates of [35S]methionine-labeled T cell blasts indicated that a molecule was specifically precipitated that consisted of two noncovalently associated polypeptide chains with apparent m.w. of 43,000 and 38,000. Both subunits displayed extensive charge heterogeneity focusing at an average isoelectric point of 5.0 and 6.5, respectively. The gp TFA-1 molecule exhibits striking similarities in its functional and structural properties to recently described clonotypically expressed T cell glycoproteins, which were shown to be involved in antigen recognition by T cells in the murine and human systems.

Animals↗