Factors influencing the autologous mixed leukocyte reaction in normal subjects

Renal transplant patients show variations in their self-reactive repertoires: a serial study

We addressed the question of whether allo-transplantation (Tx) induces breakdown of tolerance to self-antigens or alteration of the autoreactive T cell repertoire in humans. The serial variation of T cell autoreactivity was studied in the peripheral blood of 12 renal transplant patients, by autologous limiting dilution assay and autologous mixed lymphocyte reaction. Ten of 12 patients presented a positive response in autologous peripheral blood mononuclear cells in the post-Tx period, in contrast to four of 12 patients before Tx (P = 0.038). Multi-hit kinetics was found in 57% of the assays analyzed, indicating frequent regulatory control of the autologous response. Quantitative analysis performed in eight patients showed an increase in precursor frequency at >1 year post-Tx in five patients. These data indicate that autoreactivity increases or develops following Tx, in humans. Post-Tx events such as alloreactivity, infections or immunosuppression could interfere with the balance of autoreactive and regulatory cells, leading to changes in the T cell repertoires to self-antigens and eventually breakdown of self-tolerance. Further investigation is needed to elucidate whether post-Tx autoreactivity contributes to rejection, plays a regulatory role over alloreactivity or both, at separate times.

In vitro enhancement of the proliferative response of human T cells to autologous non-T cells by hydralazine

While high doses of hydralazine inhibit the proliferative response of T lymphocytes to mitogens and antigens, low doses (0.15 microgram/ml) selectively enhance the proliferative response of T cells to autologous non-T cells. The effect is especially pronounced on lymphocytes which express the HLA-DR4 allospecificity. These results suggest that the autologous mixed lymphocyte response with non-T cells may represent a useful in vitro model to analyse the mechanism(s) of the immunologic abnormalities induced by hydralazine.

Homogeneity of HLA-DQ,DR phenotypes in lymphocyte subsets of normal individuals

The study was performed to evaluate the association of HLA-DQ and DR antigens with the composition of peripheral blood lymphocytes. B cells, T cells, and T subsets were enumerated in 200 normal individuals by indirect immunofluorescence microscopy using the monoclonal antibodies OKT3, OKT4, OKT8, and OKIa1. Results were related to the HLA-DQ,DR phenotypes of the investigated population. No significant correlation between any of the lymphocyte subsets and of the HLA-DQ,DR antigens was found.

Circadian variations of autologous mixed lymphocyte reactions and endogenous cortisol

The degree of proliferation of human T cells stimulated with autologous PHA-T cells and with autologous non-T cells displays circadian variations. The highest proliferation occurs with cells isolated from blood drawn at 8 a.m. in mixed lymphocyte reactions (MLR) with autologous PHA-T cells and from blood drawn at 8 p.m. in MLR with autologous non-T cells. The circadian variations of autologous MLRs appear to reflect changes in the proliferative response of T cells. In autologous MLRs with non-T cells as stimulators the extent of proliferation was inversely correlated with the level of endogenous cortisol. The circadian variations of autologous MLRs do not reflect non-specific changes in the proliferative and stimulatory properties of T and non-T cells, since circadian variations were not observed in the proliferative response of T cells to mitogens and in allogeneic MLRs. Circadian variations of autologous MLRs must be taken into account when analyzing abnormalities of these reactions in pathological conditions.

Association of HLA-DR antigens with the autologous mixed lymphocyte reaction

A study was performed to evaluate the association of HLA-DR antigens with the proliferative response of T cells in autologous mixed lymphocyte cultures. Peripheral blood mononuclear cells from 100 normal healthy individuals were typed for HLA-DR antigens and autologous mixed lymphocyte cultures were established. A low proliferative response from autologous cultures was found with individuals bearing HLA-DR3 antigens and in individuals with only one identifiable HLA-DR antigen. In contrast, a strong proliferative response was associated with HLA-DR6 and two identifiable HLA-DR antigens. These data are consistent with the hypothesis that HLA-DR3 antigens are associated with a weak immune response gene and HLA-DR6 antigens are associated with a strong immune response gene.