Demonstration of a heterophile antigen on clone 929-L cells and their variant,LE cells,by an indirect fluorescent antibody technique

Summary It has been demonstrated that the heterophile antigen present on the surface of mouse cells can be visualized by means of the indirect fluorescent antibody technique. Depending on the fixatives used, the antigen could be demonstrated on the cell surface or intracellularly. Treating the cells with proteolytic enzymes did not affect either the reactivity of the antigen or its demonstration by the indirect fluorescent antibody technique. The pattern of immunofluorescence on the surface of clone 929-L cells, was different from that on the surface of their variant, L_E cells. The difference was probably due to a decrease in the number of heterophile antigen sites on the surface of L_E cells. This may explain the greater resistance of L_E cells to the effects of cytotoxic antibody. This investigation was supported by Research Grant MT1024 from the Medical Research Council of Canada.