Tumour-associated antigens on rat sarcoma cells identified by monoclonal antibodies

Two hybridoma clones have been produced by hybridization of murine myeloma cell line PAI and splenocytes from BALB/c mice immunized with the cells from a transplantable sarcoma induced in rat by SR-RSV. The antibody produced by hybridoma clo-ne 2C2 was of subclass IgG3 and recognized a cell surface antigen of 52 kD. It only cross-reacted with the cells from SR-RSV-induced sarcoma in hamster, but not with the cells from the chicken RSV-induced sarcoma, nor with a number of methylcholanthrene sarcomas and various other tumours of viral or another etiology developed in rat, mouse, hamster or chicken. The antibody produced by hybridoma clone 5G2 was of subclass IgG2A and recognized an antigen of 28 kD which was located under the plasma membrane and particularly in the cell protrusions and microvilli. Cross-reactions were found with all the sarcoma cells tested indicating that this antigen might represent a common sarcoma antigen of comparatively low molecular mass.