A MONOCLONAL-ANTIBODY TO ASTROCYTES, SUBEPITHELIAL FIBROBLASTS OF SMALL-INTESTINAL VILLI AND INTERSTITIAL-CELLS OF THE MYENTERIC PLEXUS LAYER

A monoclonal antibody was developed, using cultured subepithelial fibr oblasts of rat duodenal villi as the antigenic material, by in vitro i mmunization. Hybridomas were selected on cryosections of rat brain and small intestine using indirect immunofluorescence techniques. The mon oclonal antibody, termed 8E1, was very useful to label GFAP-positive a strocytes in the adult rat brain, subepithelial fibroblasts of intesti nal villi and Thuneberg's fibroblast-like interstitial cells associate d with the myenteric plexus layer. These cells are known to be stellat e in shape, forming a cellular network with extended cell processes th at communicate via gap junctions. Immature astrocytes such as radial f ibers were not immunolabeled with mAb-8E1. Immunoelectron microscopy r evealed clustered gold labeling of 8E1 antigen on the intermediate fil aments of cultured astrocytes and cultured subepithelial fibroblasts. This staining pattern was different from the continuous and linear gol d labeling of GFAP and vimentin. MAb-8E1 did not immunoblot purified h uman brain GFAP nor bovine lens vimentin, and so was not neutralized b y preabsorption with these molecules. Immunoblot analysis after SDS-PA GE showed that the antigen recognized by mAb-8E1 was a Mr 50K protein in the rat cerebra, and a Mr 56K protein in the cultured subepithelial fibroblasts. This study showed that astrocytes and some types of stel late cells share distinct antigenic properties in the components of th eir intermediate filaments.