Fc receptors of rat peritoneal macrophages: immunoglobulin class specificity and sensitivity to drugs affecting the microfilament or microtubule system.

Macrophage-cytophilic antibody activity of various immunoglobulin classes and subclasses was tested in two different rosetting systems. Cytophilic antibody activity of IgM, IgG2a and IgG1 was verified in the SRBC system, while IgM, IgG2a and IgG2c were found to be active in the trypanosome system. Sensitivity to cytochalasin B treatment of SRBC rosette formation was dependent on the class of antibody and decreased in the following order: IgM > IgG1 > IgG2a. Trypanosome rosette formation was prevented by the same drug regardless the type of antibody. Vinblastin caused an enhancement of rosette formation in the SRBC system in low concentration, except when the antibody belonged to subclass IgG1. The enhancing effect was less pronounced in the trypanosome system.