Characterization of the CD8 + CD45R + (2H4+) suppressor effector cell

In the present study, we have investigated the molecular basis for immunoregulatory function of CD8 cells after autologous mixed lymphocyte reaction (AMLR) activation. We demonstrated that the CD8+CD45R+ but not the CD8+CD45R- subset of cells was a subpopulation, with the majority of suppressor activity after AMLR activation. In contrast, cytotoxic activity against alloantigens resided in both the CD8+CD45R+ and CD8+CD45R- subsets of cells. Importantly, the treatment of AMLR-activated CD8 cells with anti-CD45R antibody or anti-CD3 antibody abolished the suppressor function of these cells, which contrasts with earlier studies showing that treatment of AMLR activated CD4 suppressor inducer cells could be blocked with anti-CD45R but not with anti-CD3 antibody. The results suggest that the CD45R antigen as well as the CD3-T cell receptor (TCR) complex have an important role in the suppressor function of AMLR-activated cells.