Impaired autologous mixed lymphocyte reaction (AMLR) reactivity of peripheral blood T cell subsets in rheumatoid arthritis.

We examined AMLR reactivity of unseparated T cells and CD4+ and CD8+ T cell subsets in peripheral blood from 11 rheumatoid arthritis (RA) patients and 10 healthy controls. T cell subsets were isolated by negative selection using complement mediated cytotoxicity. AMLR reactivity of six patients (designated RA-L was reduced below the range of the controls' responses. Five patients (designated RA-N) exhibited normal AMLR reactivity. We observed impaired AMLR reactivity of CD4+ T cells from RA-L relative to RA-N and healthy controls (P < 0.05). CD4+ T cell reactivity of RA-L was reconstituted to normal with pharmacological doses of recombinant interleukin-2 (IL-2) (100 U/ml). In contrast, CD8+ T cells from RA-L in the presence of 100 U/ml IL-2 exhibited markedly impaired AMLR reactivity relative to RA-N and healthy controls (P < 0.05). Dose-response studies revealed partial reconstitution of CD4 T cells with physiological concentrations of IL-2 (10 U/ml). To examine the possibility that in vivo pre-activation of T cells in RA accounted for the findings, T cells or subsets were cultured alone for 7 days in the presence of 100 U/ml IL-2. A trend toward enhanced reactivity of CD4+ and CD8+ T cells in L-RA relative to N-RA and healthy controls was observed, but the differences were not statistically significant. There was no correlation between reactivity of T cells alone in the presence of IL-2 and AMLR reactivity. The results suggest the possibility that abnormal AMLR reactivity of CD4+ and CD8+ T cell subsets in RA may arise as a consequence of different pathophysiological mechanisms.