Two tumor-associated membrane antigens defined by monoclonal antibodies in a transplantable sarcoma induced by Rous sarcoma virus in rat.

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