Anti-immunoglobulin and anti-CD40 stimulation induces CD25 expression by resting human tonsillar B lymphocytes.

In this report, the effect of ligation of a number of B-cell surface molecules upon expression of CD25, the 55-kDa inducible component of the IL-2 receptor complex found on T and B lymphocytes, is reported. IL-4 is the only cytokine apparently capable of promoting CD25 expression in human high-density quiescent tonsillar B cells; neither IL-10 nor IL-13 could induce CD25 expression. Cross-linking of the antigen receptors or CD40 with antibody elicited CD25 expression in a dose-dependent manner. Stimulation with anti-CD40 promoted CD25 expression in approximately 25% of B cells, while anti-Ig caused 80% or more of cells to become CD25+. In experiments where the stimuli were used in combination, some additive effects upon CD25 expression were noted, but no obvious synergistic effects could be detected.