Functional relationships between B-cell subsets: evidence for an antigen-induced B1 leads to B2 switch

Priming of mice with the TI-2 antigen TNP-Ficoll results in an increased secondary anti-TNP response to the TD antigen TNP-KLH. Spleen cells obtained from mice primed with TNP-Ficoll or TNP-LPS, but not TNP-KLH, gave augmented responses to DNP-Dextran, TNP-LPS, or LPS. In vitro treatment of spleen cells with DNP-Dextran results in an increased anti-TNP response to TNP-LPS. This effect is also obtained if mitogenic doses of Dextran and LPS are used to induce cell proliferation. We conclude that the B_i2 subset (responding to TNP-Ficoll and DNP-Dextran) switches to the B2 subset (responding to TNP-KLH) after antigen activation. The B_i1 subset (responding to TNP-LPS) may represent an intermediate stage of B-cell differentiation.