Characterization of “H‐2K,D‐like structures” on MM2 × mouse L cell hybrids. II. An “H‐2K d ‐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° lymph node cells as well as on somatic cell hybrids between MM2 tumor and mouse L cells. Preclearing of lysates from C3H.H‐2° 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‐2K d 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‐2K d reactivity. The hybid cells could induce antibodies against the H‐2K d 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‐2K d private specificity. Absorption of anti‐MM2 serum with EL4 cells did not affect the capacity of the serum to detect the H‐2K d antigen on C3H.H‐2° lymph node cells, indicating that the “H‐2K d ‐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.