Histocompatibility and T-B cell cooperation in mouse radiation chimeras.

Cooperative interaction between histocompatible as well as histoincompatible T and B cells in vivo was studied with B cell-bearing syngeneic radiation chimeras receiving syngeneic, semiallogeneic, or allogeneic A and T cells in various combinations. The results indicated the following: i) Histoincompatible T and B cells normally did not cooperate successfully for generation of antibody-forming cells. ii) Semiallogeneic (C3BF1) T cells cooperated successfully with parent-type (C3H) B cells developed in parent-type syngeneic chimeras (C3H/C3H), whereas parent-type (C3H as well as C57BL) T cells failed to cooperate with F1 (BC3F1) B cells developed in F1 syngeneic chimeras (BC3F1/BC3F1). iii) T cells obtained from C57BL/C3H or C57BL/C3BF1 chimeras, which were most likely donor (C57BL)- derived, cooperated successfully with C3H-derived B cells developed in C3H/C3H chimeras. iv) Evidence was obtained suggesting that stimulation of antibody response by allogeneic effect in the absence of syngeneic or semisyngeneic helper T cells did not take place in this experimental system. v) With the use of congenic resistant strains, it was shown that alloantigens controlled by H-2 loci, in particular by the K-I region of this gene complex, constituted the barrier of cooperative interaction between histoincompatible T and B cells. vi) Cooperation between H-2 compatible, non-syngeneic T and B cells was also disturbed in varying degrees depending on the strain combinations, thus indicating that cell surface antigens controlled by non-H-2 loci also had a significant role for the cooperative interaction between T and B cells. Problems associated with these findings were discussed.