Immunoglobulin allotypic specificities in mixed leucocyte cultures.

γG immunoglobulin synthesis was shown in mixed lymphocyte cultures. Presence in the supernatants after 6, 8 or 9 days of Gm(1) and Gm(17) specificities lacking in the lymphocyte donors' phenotypes confirmed the results already obtained in cultures with PHA. Gm(4) and Gm(11) allotypes, as well as Gm(14) and Gm(23) in the cases investigated, were found in supernatants after cultures from Gm(-4,-11,-14,-23) lymphocyte donors. With unmixed Negro lymphocyte donors, production of Gm(2), Gm(4) and Gm(21) uncommonly found in Negroes without Caucasian admixture, was demonstrated. Presence in the supernatant after culture of Gm allotypes lacking in the donors' serum phenotypes suggested that the structural genes might be under the control of regulatory genes.