The expression ofI-region gene products on lymphocytes

Mixed lymphocyte reaction (MLR) stimulation by purified T and B lymphocytes and thymocytes was studied. The MLR gene products involved were localized to theH-2 complex by the use of congenic mice differing atH-2, and to loci within theH-2 complex through the use of congenic mice bearing recombinant chromosome 17. Stimulation by T cells was investigated in detail. The role of small amounts of contaminating B lymphocytes, and that of backstimulation, was found to be of minor importance. T cells and thymocytes stimulated as well as or better than B cells in combinations differing in theI, S, and possibly parts of theD end, thus suggesting that these genetic regions control cell-surface products expressed on both T and B lymphocyte populations.Abbreviations used in this paper are MLR mixed lymphocyte reaction - GVHR graft-versus-host reaction - CML cell-mediated lympholysis - Thy-1 the gene for the T-cell antigens, synonymous with - Thy-1.1 synonym for^AKR - Thy-1.2 synonym for^C3H - MHC major histocompatibility complex - Ir genes immune response genes linked to the MHC - LPS E. coli 055.35 lipopolysaccharideFor the genetic nomenclature of theH-2 complex (H-2K, H-2D, I, S, D regions,Ia, etc.) see Kleinet al. 1974, and Shreffleret al. 1974.