Preparation of dialyzable histocompatibility antigen from BALB-c mice (cell-membrane fragments-proteolytic digestion-detergent solubilization).

Histocompatibility antigens solubilized from cell-membrane fragments of BALB/c mouse spleen and liver, by Triton X-100 and butyl alcohol, were subjected to digestion by proteolytic enzymes in an effort to obtain smaller molecular species that retained antigenic activity. Digestion with both trypsin and papain yielded two antigens of smaller molecular weights that retained the specificity of BALB/c histocompatibility antigen, as determined by the inhibition of allogeneic antibodies, agglutination of BALB/c erythrocytes, adsorption-hemagglutination versus the soluble histocompatibility antigen, and suppression of the ability of BALB/c spleen cells to produce hemolytic plaques to sheep erythrocytes. The two active products of trypsin digestion were, respectively, excluded by Sephadex G-50 but not by G-75, and excluded by G-25 but not by G-50. Papain digestion yielded one active antigen that was excluded by G-25 but not by G-50, and a smaller antigen that was excluded by G-10 but not by G-15 and, as determined by gel filtration, has a molecular weight slightly lower than vitamin B(12).