Glycoproteins of the AKR leukaemia cell surface and their relevance to leukaemia-specific surface antigens.

An attempt has been made to prepare antibodies against leukaemia-specific surface antigens by immunizing (C57 B1/6 X C3H/He)F1 mice with formaldehyde-stabilized AKR leukaemic cells. The presence of antibodies was examined by indirect immunofluorescence microscopy (IFM) and the indirect antiglobulin rosetting reaction (IARR). Galactose oxidase treatment destroyed the ability of leukaemic cells to react with antibodies prepared in the hybrid mice, an effect that was reversed by treating the enzyme-modified cells with borohydride. Analysis by immunoprecipitation and polyacrylamide gel electrophoresis of leukaemic cells, labelled by the galactose oxidase/[3H]-NaBH4 technique, indicated that a group of glycoproteins of apparent molecular weight greater than 70 000 was involved. Antibodies could be raised in AKR mice to the same group of glycoproteins by immunization with irradiated leukaemic cells or irradiated neuraminidase-treated leukaemic cells. The level of antibody raised in AKR mice had no effect on the growth of leukaemic lymphoblasts introduced subcutaneously into the host. Antibodies prepared in hybrid mice against leukaemic cells also were absorbed by lymphoid cells of pre-leukaemic 6-month-old AKR mice, indicating that contrary to previous claims in the literature antigens detected by such antisera are not related to malignancy. Hybrid mouse serum cross-reacted with antigens from purified RNA virus isolated from Abelson lymphoma, as demonstrated by the immunoelectrophoretic blotting technique. The pattern of reactivity was not appreciably altered following the absorption of antibodies directed against leukaemic cells. It is concluded that the glycoproteins detected by us may not be viral antigens but normal high molecular weight lymphoid glycoproteins with altered glycosylation patterns that are induced when the viral genomes are expressed.