H-2 haplotypes carrying identical D but different L alleles.

The B10.SAA48 congenic line was derived by transferring the H-2 haplotype of a wild mouse onto the background of the inbred strain C57BL/10Sn (abbreviated as B10). The line carries the Dw3 allele in combination with an L allele different from that present in other Dw3 strains. One possible explanation of this finding is that crossing over occurred between the D and L loci. The determinants H-2.m64 and H-2.m65 represent an inclusion doublet in which the latter never occurs without the former. Typing of B10.W lines with Ld-specific CTLs reveals the absence of this allele in all the lines, including those carrying an allele serologically similar to Ld.