Characterization of "H-2K,D-like structures" on MM2 x mouse L cell hybrids. II. An "H-2Kd-like" structure on C3H-derived tumor

Anti-MM2 serum, which had been prepared by immunizing C3H/He mice with syngeneic MM2 mouse mammary ascites tumor, immunoprecipitated "H-2K,D-like" molecules on DBA/2 and C3H.H-2 degrees lymph node cells as well as on somatic cell hybrids between MM2 tumor and mouse L cells. Preclearing of lysates from C3H.H-2 degrees lymph node cells with anti-H-2.31 serum removed all "H-2K,D-like" molecules reactive with anti-MM2 serum, indicating that the molecules detected by anti-MM2 serum are H-2Kd antigens. The anti-H-2.31 serum detected an "H-2K,D-like structure" on the hybrid cells and absorption of the anti-H-2.31 serum with the hybrid cells deprived the serum of anti-H-2Kd reactivity. The hybrid cells could induce antibodies against the H-2Kd antigen in C3H/He mice. These results indicate that on the hybrid cells, whose parental cells were both derived from C3H mice, there is an "H-2K,D-like structure" that has the H-2Kd private specificity. Absorption of anti-MM2 serum with EL4 cells did not affect the capacity of the serum to detect the H-2Kd antigen on C3H.H-2 degrees lymph node cells, indicating that the "H-2Kd-like structure" is distinct from "H-2K,D-like structure A" which was previously reported. Nine isozymes were examined and MM2 cells, mouse L cells, and the hybrids were found to have the same isozyme markers as those of the C3H/He mouse.