The role of xenoantigen in the human autologous mixed lymphocyte reaction: ability to respond in the absence of exposure to xenoantigen depends on the method of T-cell preparation

Selection of human TcR V gene families in autologous mixed lymphocyte reactions: relevance to autoimmune immunopathology

We have postulated that in vivo autologous mixed lymphocyte reactions (AMLRs) are one mechanism in the development of the intrathyroidal lymphocytic infiltration of human autoimmune thyroid disease. Such a mechanism would explain the significant numbers of self-reactive T cells present in thyroid infiltrates as evidenced by cloning studies. However, infiltrating T cells in a variety of autoimmune disease including autoimmune thyroid disease, demonstrate bias in their use of T cell receptor (TcR) V gene families. In order to examine whether such TcR V gene bias may occur secondary to non-antigen specific in vivo AMLRs rather than secondary to specific autoantigen driven mechanisms we have examined the human TcR repertoire after prolonged AMLRs in vitro. Using 5 healthy donors in 1, 2 and 3 weeks AMLRs we showed stimulation indices of 3.1-6.5 after 3 weeks. The hTcR V alpha and V beta gene repertoire was assessed using the PCR technique and revealed an almost complete repertoire of V gene families at the beginning of the studies while at the end of 3 weeks a mean of only 5.2 V alpha genes were transcribed. Less restriction was seen in the hTcR V beta repertoire with a mean of 9 V beta genes used. These data demonstrate that the AMLR is able to mimic the marked bias in hTcR V gene family use seen within the inflammatory infiltrates of autoimmune diseases.

Further characterization of the autologous mixed lymphocyte reaction: induction of double negative gamma delta T lymphocytes

To investigate the specific nature of the autologous mixed lymphocyte reaction (AMLR), we applied a method in which mixtures of NY-nonadherent responder cells and NY-adherent stimulator cells were treated with neuraminidase before culture and then cultured to assay the AMLR. This method produced a marked enhancement of DNA replication in the responder cells and the results were reproducible, regardless of the individuals tested. Using this method, we were able to make the following observations regarding the specific nature of the AMLR. (i) The AMLR is an IL-2-independent reaction, as revealed by bioassay to detect the presence of IL-2 by a blocking test using anti-IL-2R sera and as shown by the absence of mRNA for IL-2 in Northern hybridization. (ii) It is also HLA-DR dependent as proven by the fact that anti-DR sera almost completely inhibited the reaction. (iii) The AMLR was also found to induce the generation of activated CD4+ helper T cells in direct response to stimulation by NY-adherent cells, in which HLA-DR antigens were involved. (iv) Also, it induced the generation of CD4-CD8- double-negative (DN) lymphocytes, including gamma delta T cells with a cytotoxic activity against NK-resistant target cells and with a variety of lymphocyte activation markers (CD56, HLA-DR, CD25, transferrin receptors, CD38, and LFA-1). However, the AMLR did not induce the generation of NK cell markers CD16 and CD57. (v) The DN lymphocytes and gamma delta T cells appeared to be generated from the precursors of CD4-CD8- DN cells, in direct response to the stimulator cells. These results strongly suggest that the AMLR may be a phenomenon which induces the proliferative response of gamma delta T cells and their precursors, in addition to that of alpha beta T cells, particularly of CD4+ helper T cells.

Defective suppression in the autologous mixed lymphocyte reaction in patients with Crohn's disease

T helper and suppressor cell control of autologous immunoglobulin production was measured in 14 patients with Crohn's disease (CD) using autologous B cells or monocytes to stimulate regulatory T-cell activity. A pronounced defect in suppressor cell function was observed in the patient group but not in matched controls irrespective of whether B cells or monocytes were used as the stimulus. This defect was observed for IgG, A and M. This defect was seen both in patients with active disease and with inactive CD suggesting the possibility that a primary regulatory defect might exist in this disease. The patient group displayed normal helper cell function.

Possible regulation of autologous mixed lymphocyte reaction by OKM1+ NK cells

T cells are stimulated by autologous non-T cells and interleukin 2 (IL-2) is produced in the conventional autologous mixed lymphocyte reaction (AMLR) in young healthy controls. The role of cells with natural killer (NK) cell markers (OKM1+ cells or Leu 7+ cells) in the AMLR was studied. There were significant inverse correlations between the percentage of input OKM1+ cells minus monocyte (OKM1+ NK cells) and either AMLR proliferation (gamma = -0.9, P less than 0.001) or IL-2 production (gamma = -0.75, P less than 0.01) in the AMLR cultures after 7 days measured at 7 days. A statistically significant correlation was observed between the percentage of input Leu 7+ cells and AMLR proliferation (gamma = -0.64, P less than 0.05), but not IL-2 production. These results suggest that the AMLR is controlled by OKM1+ NK, perhaps acting through IL-2 regulation.

Production of a cytokine with interleukin 3-like properties and cytokine-dependent proliferation in human autologous mixed lymphocyte reaction

The autologous mixed lymphocyte reaction (AMLR) was assayed in a medium containing fresh autologous serum, by using nylon-adherent stimulator cells and nonadherent responder T cells, which were prepared from human peripheral blood mononuclear cells in the absence of fetal calf serum (FCS) to avoid any sensitization to xenogeneic protein antigens. DNA replication without a background proliferative response was induced by stimulator cells in the responder cells. The addition of monoclonal anti-HLA-DR antibody to the culture or treatment of the responder cells with complement plus anti-T4 but not anti-T8 monoclonal antibody suppressed the AMLR, suggesting that this specific AMLR involves an interaction between HLA-DR antigens and helper/inducer T cells. Regardless of this specific DNA replication, the AMLR generated no production of interleukin 2 (IL-2) and interferon gamma (IFN-gamma), both of which could be found in the allogeneic (allo) MLR. In addition, DNA replication in the AMLR was not inhibited by the addition of specific antisera for IL-2 and IFN-gamma, both of which significantly inhibited the DNA replication in allo-MLR. The AMLR was accompanied by production of a soluble factor, which could stimulate the proliferation of murine interleukin 3 (IL-3)-dependent cell line 32Dcl but not the proliferation of IL-2-dependent cell lines. This factor was also found to be responsible for proliferation of responder nonadherent cells in the AMLR. It strongly stimulated bone marrow cells, as did the murine IL-3. The factor had an Mr range, as determined by gel filtration, of 15,000-28,000, but it did not bind to fast protein liquid chromatography (FPLC)-MonoQ column. Thus, the factor is distinguishable from IL-2 in physicochemical or biological properties, but similar to murine IL-3. These results suggest that the human AMLR may be primarily a phenomenon in which non-T cells mediated by the HLA-DR antigens on the cell stimulate helper/inducer T cells to produce a lymphokine with IL-3-like properties, but no IL-2, which in turn stimulates the factor-dependent cells to proliferate.