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

In this study we have demonstrated that in the T-TA autologous mixed lymphocyte reaction (AMLR), OKT4+ T cells are the major responders; however, in the presence of additional interleukin-2 (IL-2), OKT8+ T cells also respond by proliferation. Both OKT4+ and OKT8+ T cells, activated in the T-non-T AMLR, act as stimulators in the T-TA AMLR. OKT4+ T cells activated in the T-TA AMLR suppress the proliferative response of the fresh T-non-T AMLR; control OKT4+ cells show no immunoregulatory activity in this system. In contrast, control OKT8+ T cells spontaneously suppress the proliferation of the T-non-T AMLR, but activation of OKT8+ T cells in the T-TA AMLR does not result in a further increase in the suppressor activity of OKT8+ T cells. In summary, in the T-non-T and T-TA AMLR phenotypically similar T-cell subpopulations proliferate but express distinct immunoregulatory functions and perhaps regulate the tempo of the AMLR.