Effect of angiotensin II on the Fc receptor activity of rat macrophages

Angiotensin II (At II) in the concentration range of 10(-5) to 5 x 10(-7) M inhibited active and passive erythrocyte-antibody (EA) rosette formation on monolayers of rat peritoneal macrophages (PM) but stimulated it in the range of 10(-7) -10(08) M. Cytochalasin B (CB) and vinblastin (Vb) inhibited the dose-dependent biphasic effect of At II on the Fc receptor (FcR) expression of macrophages. The hormone acts on the last step of rosette formation, i.e. on the binding of sheep red blood cells (SRBC) but does not interfere with the binding of 125I-Ig to FcR. The influence of At II on macrophage rosette formation can be modified by changes in the density of FcR-Ig complexes on the surface of target cells, by the nature of the immunoglobulin (sub)classes involved in rosette formation, and by the biological properties of rosette-forming corpuscular antigen. Based upon the above results we suggest that At II exerts its effect on the contractile elements associated with the cytoskeleton of the macrophage.