IDENTIFICATION OF FC-GAMMA-RI, II AND III ON NORMAL HUMAN BRAIN RAMIFIED MICROGLIA AND ON MICROGLIA IN SENILE PLAQUES IN ALZHEIMERS-DISEASE

Using monoclonal antibodies to the three known human leukocyte IgG rec eptors, FcgammaR, we examined the expression of FcgammaR in normal bra ins and in Alzheimer's disease. We found FcgammaRI, II and III immunor eactivity in senile plaques and on ramified microglia throughout the c ortex and white matter of normal and Alzheimer's disease brains. Fcgam maRI expression was independently confirmed by a murine isotype bindin g study. These findings suggest that intrinsic FcgammaR may play an im portant role in normal and disordered immune-related processes in the brain. They support the idea that microglia are brain macrophages.