Discrete association of CD3 and CD4 molecules in T-cell stimulation acting through the autologous mixed lymphocyte reaction and the CD3/T-cell receptor complex in human autoreactive T-cell clones

Abstract

To investigate autologous antigen recognition, we developed two autoreactive CD4+ T-cell clones, A2 and A10, maintained with non-T cells and IL-2. Autologous non-T-cell stimulation of the T-cell clones resulted in a decrease in cell surface expression of CD4, whereas the expression of CD2, CD3, and WT31 was unchanged. Activation of the autoreactive T-cell clones by cell surface binding anti-CD3 MoAb, as a specific antigen stimulator of the T-cell receptor complex, induced cell surface antigen comodulation of CD3, CD4, and WT31. These data suggest a discrete association of CD3 and CD4 molecules in T-cell stimulation, acting through the autologous mixed lymphocyte reaction and the CD3/T-cell receptor complex. PMA treatment resulted in concomitant down-regulation of CD3 and CD4 but calcium ionophore treatment did not. Thus, it appears that phosphorylation of CD3 leads to the down-regulation of surface antigens of CD4.