Proliferation of gemistocytic cells and glial fibrillary acidic protein (GFAP)-positive oligodendroglial cells in gliomas: a MIB-1/GFAP double labeling study.

Large gemistocytic cells are well-known elements of glial tumors. Recently, miniature gemistocytic cells and neoplastic glial fibrillary acidic protein (GFAP)-positive oligodendroglial cells, which are regularly seen in oligodendrogliomas, have been termed "transitional cells". The proliferative activity of the gemistocytic cell types and the GFAP-positive (gliofibrillary) oligodendrocytes was determined in eight astrocytomas, seven gemistocytic astrocytomas, eight glioblastomas, two monstrocellular glioblastomas, seven oligodendrogliomas and three mixed oligo-astrocytomas by immunohistochemical staining of the proliferation marker MIB-1 in combination with immunostaining for GFAP. Both large gemistocytic cells and the transitional cells showed cytoplasmic GFAP-positive staining. Neither in the classic gemistocytes nor in the minigemistocytes nuclear immunostaining for the MIB-1 antibody was observed. In contrast, MIB-1 staining was seen in the gliofibrillary oligodendrocytes. It is concluded that both large and miniature gemistocytic cell types contrast with gliofibrillary oligodendrocytes by their inability to proliferate.