II-BLOOD GROUP ANTIGENS ON FIBROBLAST CELL-SURFACES

Six cold agglutinin-containing sera, directed against I or i antigens, gave immunofluorescent staining of stromal cells in frozen sections of tissues in vivo and in monolayer cultures of fibroblasts in vitro. Microcytotoxicity tests showed that the cold agglutinins were cytotoxic to fibroblasts. The immunofluorescent staining probably represents serum reactivity with Ii antigens on fibroblast cell surfaces because the reactions were neutralized by serum absorption with fibroblasts or red blood cells, but not by absorption with hepatocytes. The sites on fibroblasts binding to cold agglutinins were resistant to tryptic digestion and remained on the glass substratum after cell detachment induced by trypsin. © 1979.