MMGT1, also known as EMC5, is comparable with primary microglial cells with respect to morphology, presence of acetylated low density lipoprotein receptor, non-specific esterase, CD63, major histocompatibility complex antigens and CD11, and binding for Ricinus communis agglutinin. Primary microglia as well as MMGT1 cells are negative for glial fibrillary acidic protein. Different MMGT1 strains are obtained after subcloning, two of which resembled histiocytes (F4/80 and BM-8). These cell strains, MMGT12 and 16, are able to opsonize latex beads, and could be induced by endotoxins (LPS) to secrete TNF-alpha, IL-1, IL-6, TGF-beta, and EGF.