Expression of FcIgG receptors on cultured fetal rat brain cells. Studies on normal, preneoplastic and malignant cells.

Abstract

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).