Tumor immunity to murine plasma cell tumors. V. Demonstration of a unique tumor antigen that is not associated with the myeloma idiotype
MacKenzie, M.R.; Burton, R.C.; Warner, N.L.
International Journal of Cancer 21(6): 789-795
A plasma-cell tumor, Cl. 18 of C3H/He derivation, exhibited a unique tumor-associated antigen (TAA) which was detectable in vitro and also as a tumor-associated transplantation antigen (TATA) in vito. Immunoglobulin idiotypic determinants were thought to be prominent TATA. Studies were performed to determine whether the unique TAA of Cl. 18 is its immunoglobulin [Ig] idiotypic determinant. Mice immunized with Cl. 18 myeloma protein (Cl. 18 MP) exhibited some protection to subsequent challenge with Cl. 18 tumor cells indicating that the Cl. 18 idiotypic determinant can indeed act as a weak TATA. However, in vitro lysis of Cl. 18 tumor cells by cytotoxic T [thymus-derived] cells induced in vitro to Cl. 18-unique TAA was not blocked by Cl. 18 MP, in soluble form or when bound to sheep red blood cells. Spleen cells from mice immunized to Cl. 18 MP in vivo did not undergo a secondary cytotoxic response when stimulated in vitro by Cl. 18 tumor cells. When C3H mice were immunized with tumor cells they were highly resistant to a subsequent challenge with Cl. 18 tumor cells, and spleen cells from these mice showed a marked secondary cytotoxic response when stimulated in vitro by Cl. 18 tumor cells. Spleen cells from these mice, however, did not mount a secondary cytotoxic response when stimulated with Cl. 18 MP in vitro. The unique TAA present on Cl. 18 cells is probably not the idiotypic Ig determinant, although both antigens can act as TATA in vivo. Although some plasmacytomas may express cell surface Ig idiotypic antigens, these are probably not the major surface antigens that act as tumor-associated antigens.