Molecular heterogeneity of D-end products detected by anti-H-2.28 sera. II. B10.D2(M504) (H-2dm1) mutant fails to express one of the two H-2.4-, 28 + Dd region molecules.

By the technique of antibody-induced redistribution of cell surface antigens (capping), two serologically distinct molecules that do not react with anti-D-private sera were detected in the products of Dd and Dq regions. One of them is H2L, H-2Ld and H-2Lq. The other molecule is different from H-2L as well as from any known Qa molecule and it is either an H-2-like or Qa-like molecule. We designate it provisionally L2d and L2q, respectively. All these molecules carry the specificity H-2.28. Nevertheless, one antiserum against a H-2.28-like specificity, D29 (s X k anti-m) shows differences between these molecules. This antiserum reacted with H-2Ld and H-2Lq but not with L2d and Leq molecules. The same antiserum reacted, however, only with the H-2.4 positive (H-2D) molecule in mutant B10.D2 (M504) (H-2dml) cells. No antipublic serum was found that was able to distinguish different H-2.4 negative molecules in dml haplotype. The serological characterization of H-2.4 negative molecule in dml mutant indicated that this molecule is similar to the L2d molecule detected in the parental H-2d haplotype. Thus, dml mutant fails to express the H-2Ld molecule but does express H-2.4 negative, H-2.28 positive molecule, analogical to L2d. Together with our recent data demonstrating previously unknown molecules in the products of Dd and Kd regions, six serologically distinct molecules other than Qa-2 controlled by H-2d haplotype could be detected -- H-2K1d, H-2K2d, H-2Dd, H-2Md, H-2Ld, and L2d. BALB/c-H-2dm2 mutant fails to express H-2Ld and L2d molecules, while B10.D2(M504) (H-2dm1) mutant fails to express H-2Md and H-2Ld molecules.