Inhibition of T gamma rosette formation by the sera from patients with systemic lupus erythematosus. Relation to T gamma-specific antilymphocyte antibody.

The cytotoxic activities of lupus sera were measured against IgG Fc-receptor-bearing T lymphocytes (T gamma cells) and T lymphocytes lacking this receptor [T gamma (-) cells], and the activities were compared with the inhibitory activities of the sera for the formation of rosettes (T gamma rosettes) between T lymphocytes and ox erythrocytes sensitized with IgG antibody. The cytotoxic activities of the sera against both T gamma and T gamma (-) cells well correlated with their T gamma rosette inhibitory rates. Also, the cytotoxic activities after the removal of IgM antibodies strongly correlated with the inhibitory rates. Among them, the highest correlation was observed between IgG T gamma-specific cytotoxic antibodies and T gamma rosette inhibitory rates of the sera. Gel filtration, ultracentrifugation, pepsin digestion, and reduction and alkylation of the sera revealed that main inhibitory activities were contained in IgG fractions. These results suggested that IgG T gamma-specific antibody suppressed T gamma rosette formation and might contribute to the reduction of T gamma cell number in patients with systemic lupus erythematosus.