Reactivity of Lymphoid Cells from Mice Humorally Tolerant to Histocompatibility Antigens

Abstract

WE have solubilised and partially purified the H-2^a histocompatibility antigen of the mouse. All of the detectable H-2^a serological specifIcities have been preserved¹ including those occurring in a single allelic form: four at the D locus and twenty-three at the K locus. The immunogenic character¹ as revealed in second set skin and embryonic heart rejection and specific immunological enhancing capacity² against two strain A tumours remained intact. Thus it was presumed that our soluble antigen, occurring in a single narrow peak (F2 fraction) following G-150 Sephadex column fractionation, represented a complete molecule since the H-2^d and H-2^k loci containing the determinants detected are located at opposite ends of the H-2 complex. This F2 fraction was capable of inducing humoral tolerance but not, however, cell-mediated tolerance³ in congenic B10.D2 mice treated with daily injections of the F2 fraction from birth. The B10.D2 mice made tolerant to this material were unable to produce cytotoxic, haemagglutinating or enhancing antibodies but nonetheless effectively rejected B10.A skin grafts. Presumably this antigenic material made tolerant the bone marrow derived B lymphocytes.