Autologous mixed lymphocyte reaction in man. XIII. Characterization of the T-T autologous mixed lymphocyte reaction

The effect of carbamazepine and its reactive metabolite, 9-acridine carboxaldehyde, on immune cell function in vitro

Carbamazepine, a widely used anticonvulsant, is associated with a wide range of adverse reactions including agranulocytosis, aplastic anemia and drug-induced lupus. It has also been reported to alter immune function in a variety of ways. We had previously demonstrated that carbamazepine is oxidized by activated neutrophils to several metabolites and this leads to covalent binding of the drug to the cells. It appears that the major metabolite responsible for this binding is 9-acridine carboxyaldehyde. In this study the effects on leukocyte function of carbamazepine and its leukocyte-generated metabolites were compared. Incubation of lymphocytes with 100 microM 9-acridine carboxaldehyde resulted in 40% cell death while carbamazepine at this concentration had no effect on viability. The effect on the immune cell function was investigated using the autologous mixed lymphocyte reaction (AMLR), allogeneic mixed lymphocyte reaction (MLR), lymphocyte transformation test (LTT) and mitogenesis assays. Alteration of immune cell function by the reactive metabolite, 9-acridine carboxyaldehyde, was demonstrated by an increased proliferation at low concentrations (0.08-1.0 microM) and inhibition at high concentrations (20-100 microM) in the allogeneic MLRs. Carbamazepine had no measurable effect. 9-Acridine appears to have more of an effect on B-cells since this augmentation-suppression phenomenon was also observed in mitogenesis assays with Staphylococcus aureus, a B-cell mitogen, in contrast to mostly inhibition observed in the mitogenesis assay with phytohemagglutinin, a T-cell mitogen. Again, carbamazepine had no measurable effects at comparable concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

CD8+/DR+ T gamma cells inhibit the autologous mixed lymphocyte reaction

The proliferative response of T cells during autologous mixed lymphocyte reactions (AMLR) was affected by depletion of IgG Fc receptor+ T lymphocytes (Tg). Removal of Tg cells resulted in enhanced proliferation, and EA-rosette isolated Tg cells, when added to AMLR cultures as irradiated third components, reduced the uptake of 3H-thymidine by 63-87% in a dose-dependent manner. Negative selection using an avidin-biotin affinity chromatography technique demonstrated that the suppression was mediated by DR+ Tg cells; the major proportion of which also expressed the CD8 antigen. By comparing AMLR supernatants collected from control (lacking Tg) and suppressed (containing Tg) cultures on days 2, 3, and 4, it was established that supernatants from suppressed cultures had significantly reduced levels of cytokine activity. These data indicate that the CD8+/DR+ Tg cells function as suppressor cells during an AMLR and reduce the proliferative response by inhibiting AMLR responder T cells from producing the cytokines necessary for in vitro growth.

The autologous mixed lymphocyte reaction in primary biliary cirrhosis: analysis of activation and blastogenesis of autoreactive T lymphocytes

Blastogenesis of autoreactive T lymphocytes in the autologous mixed lymphocyte reaction has been shown to be decreased in patients with primary biliary cirrhosis, but the mechanisms underlying this abnormality are not known. To investigate further the abnormal autologous mixed lymphocyte reaction in primary biliary cirrhosis, we measured the activation of autoreactive helper/inducer and suppressor/cytotoxic T lymphocytes concurrently with blastogenesis in 35 patients with primary biliary cirrhosis and 18 healthy controls. Blastogenesis was diminished in autologous mixed lymphocyte reaction cultures from primary biliary cirrhosis patients compared to the control subjects (25,273 +/- 20,259 dpm vs. 36,004 +/- 14,951 dpm, p less than 0.02), but cultures from patients with primary biliary cirrhosis contained significantly increased percentages of activated helper/inducer and suppressor/cytotoxic T lymphocytes: 20.6 +/- 7.9 vs. 15.5 +/- 5.3%, p less than 0.008, and 9.8 +/- 7.8 vs. 5.4 +/- 3.0%, p less than 0.02, respectively. These findings were not related to the histologic stage of liver disease or to the serum bilirubin concentration and were not associated with abnormalities of lymphocyte subsets in fresh peripheral blood specimens. We conclude that the percentage of autoreactive T lymphocytes in autologous mixed lymphocyte reaction cultures from peripheral blood is increased in patients with primary biliary cirrhosis and diminished blastogenesis in autologous mixed lymphocyte reaction cultures is not due to the loss of autoreactive T lymphocytes from peripheral blood. Diminished blastogenesis reflects a diminished proliferative response of activated, autoreactive T lymphocytes in primary biliary cirrhosis. Possible mechanisms that may account for the paradoxical findings of decreased blastogenesis and increased activation of autoreactive T lymphocytes in primary biliary cirrhosis are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Autologous mixed lymphocyte reaction in man. XX. The cellular and molecular basis of deficient T-T AMLR in aging humans

In the T-T AMLR, suppressor functions are generated, and because in human aging a deficiency of suppressor function has been observed, we examined the T-T AMLR in aging humans. Non-T cells were irradiated and used as stimulators against fresh autologous responder T cells to generate activated T cells (TA). TA cells were irradiated and used as stimulators against fresh autologous responder T cells (T-TA AMLR), CD4+ cells (CD4-TA AMLR), or CD8+ cells (CD8-TA AMLR) in the presence or absence of recombinant interleukin 2 (rIL-2). T cells from young and aging subjects were stimulated with phytohemagglutinin and examined for the expression of IL-2 receptors (IL-2R) and transferrin receptors. A significant decrease in T-TA, CD4-TA, and CD8-TA AMLR was observed in aging humans when compared with simultaneously studied sex-matched young controls. In vitro addition of rIL-2 resulted in an enhanced AMLR in both young and aging subjects; however, the total [3H]thymidine incorporation by T cells and T-cell subsets from aging in the presence of rIL-2 was lower than that of young subjects' T cells and T-cell subsets in the presence of rIL-2. The net increase (over the baseline values) in [3H]thymidine incorporation in T-TA and CD8-TA by rIL-2 was significantly less in the aging group when compared to the young group. In contrast, the rIL-2-induced net increase in [3H]thymidine incorporation in CD4-TA AMLR in both groups was comparable. T cells expressing IL-2R and transferrin receptors were of similar proportions in two groups. These data show a deficiency of the T-T AMLR in aging humans that appears to be, at least in part, due to deficient response to rIL-2. This deficiency of the T-T AMLR might be responsible for deficient suppressor activity, hyperimmunoglobulinemia, and the presence of autoantibodies in aging humans.

Autologous mixed-lymphocyte reaction in man. XVII. In vitro effect of ion channel-blocking agents on the autologous mixed-lymphocyte response

The in vitro effect of ion channel-blocking agents verapamil (V), 4-aminopyridine (4AP), tetraethylammonium (TEA), and quinine (Q) was examined on the proliferative response of human peripheral blood T lymphocytes in the autologous mixed-lymphocyte reaction (AMLR). All the above channel blockers in a dose-dependent manner inhibited the AMLR. Tetramethylammonium (TMA), an analog of TEA that does not block K+ channel currents, did not inhibit the AMLR. 4AP at 1 mM/ml concentration inhibited the expression of IL-2 receptors, as defined by monoclonal antibody anti-Tac, on T-cell activated in the AMLR. In vitro addition of recombinant interleukin 2(rIL-2) completely corrected the inhibition of the AMLR by channel blockers. Furthermore, the concentrations of ion channel blockers required for blocking 50% response of T cells in the AMLR was much lower than that reported for 50% block of T-cell proliferation in response to phytohemagglutinin or in allogeneic mixed-lymphocyte culture (MLC). These data suggest a role of ion channels in T-cell functions and show that the AMLR provides a more sensitive system, as compared to lectin stimulation or MLC, to examine any immunosuppressive effects of ion channel-blocking agents in disease states where they are used as therapeutic modalities.

In the murine syngeneic mixed lymphocyte reaction, one T cell subset replicates in the presence of B cells or macrophages and replication is inhibited by simultaneous presence of both stimulator cells

The murine T-non-T cell syngeneic mixed lymphocyte reaction has been examined to determine whether B cells and macrophages stimulate the same or different subpopulations of T cells. By using experiments in which replicating T cells were suicided, we found that the two different stimulators caused replication of what appears to be the same subset(s) of T cells. Since B cells and macrophages carry the same stimulating antigens (class II plus mls or others), one would expect them to stimulate the same T cell subpopulations were it not that they have been reported to stimulate two different subpopulations in humans. When B cells and macrophages were simultaneously used as stimulators, diminished T cell replication occurred. We have found the reduced response is not attributable to exhaustion of culture nutrients or to displacement of the response peak. Other possibilities to account for this marked reduction have been discussed from the viewpoint of suppression emanating from macrophages and/or T cells.