High avidity periventricular IgG-Fc receptor activity in human and rabbit brain

Periventricular tissues from human and rabbit brains were examined for receptors for the Fc domain of immunoglobulin G (Fc receptors). Fc receptors were demonstrated using antibody-coated erythrocytes (EIgG) and covalently cross-linked rabbit IgG. EIgG adhered specifically to nonneuronal periventricular glial areas and was inhibited by IgG and Fc fragments, but not by Fab fragments or albumin. EIgG adherence was 50% inhibited with 6.7 X 10(-9) M IgG. This is 1/1000 the amount of IgG required to produce 50% inhibition of EIgG adherence to arachnoid FcR. Studies with covalently cross-linked IgG demonstrated a linear relationship between ligand size and inhibition of EIgG adherence. Uncoated erythrocytes, IgM-coated erythrocytes, or F(ab')2-coated erythrocytes failed to bind to periventricular tissue. Many nonspecific esterase-positive cells were found in the area of periventricular EIgG adherence; this esterase activity was sensitive to fluoride. These results provide, for the first time, evidence of inherent IgG receptor activity in the periventricular tissues, and suggest that the periventricular tissues play a protective role in the removal of IgG or IgG-antigen complexes which have entered the cerebral spinal fluid.