Murine lymphocyte alloantigens. II. The Ly-7 locus.

The murine Ly-7 locus was identified by the reactivity of alloantisera prepared as B6,C-H-2d x CXBG)F1 anti-CXBK. Most strains, except C57BL/6 and related strains, were Ly-7.2+. Absorption analysis demonstrated that the Ly-7 specificity was only found on lymphocytes and was absent from liver, kidney, brain, and red blood cells. Direct testing by cytotoxicity and protein A rosetting showed that Ly-7 is expressed in very low amounts on thymocytes, but is readily detectable on more mature T and B lymphocytes (including antibody-forming cells), with the greatest expression on B cells. Typing backcross mice with Ly-7.2 Ly-4.2, H-2.33 antisera showed that Ly-7 is not linked to the Ly-4 or H-2 loci. In raising the antisera by hyperimmunization, it was found that the antibody response to the Ly-7.2 specificity was influenced by an H-2-linked immune response gene.