Identification of FcγRI, II and III on normal human brain ramified microglia and on microglia in senile plaques in Alzheimer's disease

Using monoclonal antibodies to the three known human leukocyte IgG receptors, FcγR, we examined the expression of FcγR in normal brains and in Alzheimer's disease. We found FcγRI, II and III immunoreactivity in senile plaques and on ramified microglia throughout the cortex and white matter of normal and Alzheimer's disease brains. FcγRI expression was independently confirmed by a murine isotype binding study. These findings suggest that intrinsic FcγR may play an important role in normal and disordered immune-related processes in the brain. The support the idea that microglia are brain macrophages.