Human leucocytes express at least two different Fc receptors specific for IgG (Fc gamma R). A low avidity receptor (Fc gamma Rlo) is found on tissue macrophages, neutrophils and NK cells. This receptor is recognized by monoclonal antibody 3G8, which does not react with a high avidity Fc receptor (Fc gamma Rhi) found on blood monocytes and macrophages. We have been interested in the physiological function of these two receptors, which have been shown to differ by more than 200-fold in avidity. Since Fc gamma Rhi is virtually saturated by IgG present in the serum, we felt that it would not function efficiently for clearance of immune complexes, whereas Fc gamma Rlo binds monomer very poorly. Immunoperoxidase staining with MAb 3G8 of frozen sections reveals the presence of Fc gamma R10 on Kupffer cells and in the red pulp of the spleen. Evidence will be presented demonstrating that infusion of MAb 3G8 into chimpanzees dramatically alters clearance times of autologous erythrocytes opsonized with chimpanzee IgG. These results suggest that Fc gamma Rlo is primarily responsible for immune complex clearance in vivo, and that MAb 3G8 may be of clinical use in the treatment of certain autoimmune diseases.
|Number of pages||13|
|Journal||Ciba Foundation symposium|
|State||Published - 1986|