Abstract
T-B collaboration has been studied in a secondary response to sheep erythrocytes using either syngeneic or allogeneic T- and B-cell combinations. T cells prepared from tetraparental bone marrow chimeras (TBMC), carrying H-2 determinants of one parental strain only, cooperated with syngeneic, as well as with allogeneic B cells carrying the alloantigens to which the T cells had been tolerized in the chimeric environment. When TBMC-derived cells of a single H-2 specificity were transferred with a mixture of TBMC-derived B cells of both H-2 types of the parental strains, no preference for syngeneic cooperation was found. The data therefore suggest that the presence of differing H-2-complex determinants on the allogeneic T- and B-cell populations of the two different strain combinations tested do not interfere with T-B collaboration when the cell populations studied are mutually tolerant.