Shedding of Fc receptor from mononuclear cells and their ability of binding IgG1 and IgG3 anti-Rh/D antibodies.

Fc receptors for IgG1 and IgG3 on peripheral blood lymphocytes and monocytes were studied before and after temperature shift from 4-37 degrees C. The investigations were performed in the EA test using human erythrocytes sensitized with anti-Rh/D/antibodies of IgG1 (EA IgG1) and IgG3 (EA IgG3) subclasses. It occurred that lymphocytes and monocytes were able to bind IgG1 and IgG3 antibodies before and after shedding, however, lower percentage of rosette was observed after temperature shift. This decrease was similar in the EAIgG1 and EAIgG3 tests. The supernatants obtained during shedding occurred to contain active Fc receptors since the inhibition of rosette formation was obtained after the incubation of sensitized erythrocytes with these supernatants. IgG1 as well as IgG3 myeloma proteins inhibited rosette formation in both EAIgG1 and EAIgG3 tests. Our data might suggest that IgG1 and IgG3 anti-D antibodies are able to bind to the same Fc receptor on lymphocytes as well as on monocytes.