Concanavalin A induces a T-cell dependent activation of human tonsil B cells in vitro.

Tonsillar lymphocytes cultured for 7 days in serum-supplemented RPMI-1640 medium were stimulated with Con A or PWM. IgM production was assessed by a hemagglutination inhibition assay. IgM was produced after Con A as well as PWM stimulation. Our data show that T-cell irradiation and/or addition of small numbers of T cells to the responding B-cell population facilitate(s) IgM synthesis. In particular in Con A-stimulated cultures the T-cell number is critical in regulating the appearance of suppressor effects. The results are discussed in terms of the various subpopulations possibly involved in the response to these mitogens.