Simultaneous Responses To Td, Ti-1 And Ti-2 Antigens Originate From Both Specific And Multipotent Precursors

The classification of antigens into TD, TI-1 and TI-2 varieties raises the question of whether responses to these antigens are produced by distinct or identical subpopulations of B cells. In the present study we have examined the extent of intraclonal specificity variation in the progeny of PFC appearing after stimulation with two unrelated antigens. Mouse lymphoid cells were stimulated with pairs of TD and TI antigens, PFC were individually cultured and daughter PFC examined for their specificity. In all combinations used, PFC responding to TD antigen engendered, after 48 h of culture, a high frequency of PFC daughters expressing one or the other antibody specificity, notwithstanding the specificity of parental PFC. However, PFC responding to TI antigens seemed less subject to variation in specificity, and PFC daughters engendered after a 48 h culture period were, in the majority, of the parental specificity. These results are analysed in relation to different subpopulations of B cells.