Expression Of Fcigg Receptors On Cultured Fetal Rat-Brain Cells - Studies On Normal, Preneoplastic And Malignant-Cells

The expression of FcIgG receptor (FcR) was studied during various stages of growth and subculturing of: (1) fetal rat brain cells (FBC); (2) FBC during in vitro neoplastic transformation after a transplacental pulse of the alkylating carcinogen ethylnitrosurea in vivo, and (3) an established neoplastic brain tumor cell line. Hemadsorption of antibody-coated sheep erythrocytes was used for the detection of FcR-positive cells. Such cells were not detected in cryostat sections of fetal rat brains, but in primary cultures of FBC 1 day after the explantation. FcR-positive cells were present throughout the logarithmic-growth phase. When reaching confluency after 5–7 days in culture, FcR-positive cells could not be detected. In the secondary cultures the occurrence of FcR-positive cells showed a similar variation related to growth: The growth-related receptor was also present on cells growing into arteficial defects in confluent cultures, while the resting cells in the same cultures were FcR-negative. With further subculturing the cells became epithelioid and slowly growing without FcR. Morphologically induced differentiation of such epithelioid cells by 12-O-tetra-decanoyl phorbol-13-acetate did not change the FcR expression. We did not detect any change in the receptor expression related to the malignant transformation, and the malignant cell line was FcR-negative. Expression of FcR on FBC undergoing malignant transformation therefore seems to be mainly connected to the mode of growth (log-phase versus confluence).