Independent segregation of two functional markers expressed on the same B-cell subset in the mouse: the Mls determinants and LPS receptors.

Mice of the C3H/Tif strain display a mixed leukocyte reaction (MLR) with all H-2k strains carrying any of the known alleles of the Mls locus. In particular, C3H/Tif is incompatible with the related substrain C3H/HeJ, from which it also differs at the locus responsible for the recognition of lipopolysaccharides (LPS) as B-cell mitogens, and at the Mod-1 locus. Our genetic analysis indicates that the MLR incompatibility between these strains is not H-2-linked and segregates as controlled by a single locus, most probably identical to Mls, for which the C3H/Tif strain expresses a previously unidentified allele, Mlse. Moreover, segregation data show that this locus assorts independently of LPS responsiveness and that neither marker is closely linked to the Mod-1 locus in linkage group II.