Detection of Fc-receptor-bearing human lymphocytes. The majority of Tμ cells carry HLA-DR antigens

Abstract

The Fc receptors of peripheral blood mononuclear cells were studied. The cells detected with anti-Rh Ripley-coated erythrocytes (EA Hu) were the same as those detected with rabbit IgG-coated ox erythrocytes (EA Ra), since depletion of EA-RFC with one system caused an almost complete removal of EA-RFC as detected with both systems. For the isolation of Fc-receptor-bearing T lymphocytes (Tγ and Tμ cells) untreated, AET-treated, and neuraminidase-treated sheep red blood cells were equally good. The effect of anti-HLA-DR antibodies and anti- β 2 microglobulin (anti- β 2m) antibodies on EA-rosette formation was also studied. Anti-HLA-DR antibodies completely inhibited EA IgM-rosette formation of T lymphocytes, whereas no inhibition of EA IgG-rosette formation was observed in any mononuclear cell population. Anti- β 2m antibodies completely inhibited both EA IgM- as well as EA IgG-rosette formation. Less than 5% of freshly isolated T lymphocytes formed EA IgM rosettes and were HLA-DR positive. In contrast approximately 50% of T lymphocytes formed EA IgM rosettes and were HLA-DR positive after overnight incubation. More than 90% of the Tμ cells were HLA-DR positive. Thus, overnight cultivation of T lymphocytes induce expression of HLA-DR antigens along with the Fcμ receptors. This is first report of HLA-DR antigens detected on the majority of nonstimulated human T cells.