Serological characterization of previously unknown H-2 molecules identified in the products of the Kd and Dk region.

The molecular relationship between H-2 private and some public specificities was studied in C3H.OH (H-202) mice using surface-antigen re-distribution methods. Besides the Kd- and Dk-region antigens, which can be capped by antisera against the private and public specificities characteristic for a given allele, a previously unknown type of molecule was found in the products of both the Kd and Dk regions. These can be capped by the respective anti-private serum but not by antisera against some public specificities. The two Kd-region molecules are provisionally named H-2K1d and H-2K2d. We detected them on H-202 (Kd, Id, Sd, Dk) and also on H-2dx (Kd, If, Sf, Ddx) T lymphocytes. Similarly, the two types of molecules detected on the products of the Dk region are provisionally named H-dD1k and H-2D2k. The serological characteristics of these molecules are described. When compared with the products of the Dd region, in which we previously described three different molecules (H-2Dd, H-2Md, and H-2Ld), the mutual relationship between H-2K1d and H-2K2d as well as between H-2D1k and H-2D2k appears to be similar to that between H-2Dd and H-2Md. In the absence of relevant recombinants or informative biochemical data, it is, however, difficult to establish homology between molecules produced by different K- and D-region alleles.