Evidence for separate subpopulations of B cells responding to T-independent and T-dependent immunogens.

BALB/c spleen cell cultures were double-challenged with optimal doses of TNP-T independent and TNP-T-dependent immunogens. The anti-hapten response was additive or synergistic in double challenged cultures compared to the response in cultures challenged with either immunogen alone. A high, suppressive dose of either immunogen did not prevent the response to an optimal dose of the second immunogen in the same culture. Spleen cell cultures were also double challenged with combinations of two T-dependent or two T-independent immunogens. Addition or synergy in the anti-hapten response only occurred when the double challenge consisted of a mixutre of T-dependent and T-independent immunogens. These results are consistent with the proposed B1B2 classification of B cell subpopulations.