Antigenic changes of DBA/2J mastocytoma cells when grown in the BALB/c mouse.

A 10-day growth period of the DBA/2J strain-specific P815-X2 mastocytoma in the BALB/c mouse altered the antigenicity of the tumor cell surface. The in vivo-modified mastocytoma cells differed from mastocytoma cells grown in the original DBA/2J mice in suspectibility to lysis by immune peritoneal exudate cells, in vitro antigenic recognition by cytotoxic T-cells, and immunizing capacity in allogeneic C57BL/6 mice. Propagation of the altered tumor cells in the original host or maintenance in tissue culture for 40 hours restored complete susceptibility to lymphocyte-mediated cytotoxicity.