Enumeration of H-2-gene products: failure to detect L molecules in the H-2b haplotype

Sequential immunoprecipitation analyses have been performed in an attempt to demonstrate products of the H-2L locus of the H-2b haplotype. Antisera to the private H2Db specificity, H-2.2, were used to pretreat antigens preparations, and the supernatants were then examined with antisera to public H-2b specificities, including antisera cross-reactive with H-2Ld. In no case was a separate molecule detected. These findings are in marked contrast to the results of similar sequential precipitation analyses o;n H-2d and H-2q antigen preparations, in which L molecules are readily detected. Other sequential precipitation analyses were also performed on H-2k- and H-2s-antigen preparations and also failed to demonstrate distinct L molecules (data not included). We conclude that L molecules are either present in too low amount to be detected among the products of these other haplotypes, or that the H-2L gene represents a recent duplication and is present only in the H-2d and H-2q haplotypes among the inbred mouse strains surveyed.