Heterogeneity of B cells: direct evidence of selective triggering of distinct subpopulations by polyclonal activators.

This investigation was undertaken to assess directly the previous postulate that distinct subsets of B cells in the adult mouse spleen are selectivity triggered by different polyclonal B-cell activators (PBA). Several strains of mice and lipopolysaccharide (LPS), purified protein derivative of tuberculin (PPD), and dextran sulphate (DS) were used in this study. Two experimental approaches were used: stimulation after addition of two PBAs simultaneously to cell cultures and eliminating the responding population to one PBA, by a hot pulse of radioactive thymidine, on a later response to another PBA. The results of these experiments indicated that DS stimulated a cell population completely different from that stimulated by the LPS- and PPD-sensitive cells. When LPS and PPD stimulations were compared, it was found that the cells responding to these PBAs were largely distinct, although some cells were sensitive to both these PBAs. The extension of the overlaps in these subsets (the number of cells that could be activated by either PBA) was found to vary from one strain to another. These experiments gave direct evidence of the existence of subsets that can be activated by different PBAs. The present results also provided indications of the functional performance of distinct subsets of B cells on activation.