engleski

Differential regulation of type I cytokines/cytokine receptors on naive and memory B cells

B cells can be skewed to differentiate along &laquo ; Type 1&raquo ; or &laquo ; Type 2&raquo ; pathways and correspondingly impact upon the direction of an immune response. However, scant information is available on how this might be regulated. Here we showed that naive and memory tonsilar B cells are remarkably similar in their potential for IL-12 responses as revealed by basal and regulated expression of receptors for this initiating Type 1 cytokine. BCR-engagement provided a priming signal for the induction of IL-12Rb1 which can be potentiated by IFN-g and CD40 ; IL-12 itself prompted the down-regulation of its b1 receptor. IL-12Rb2, essentially absent on both naive and memory cells, was induced solely by IFN-g and then only on a minor subset of each. The expression of WSX-1, an orphan receptor for newly described IL-27, was higher on freshly isolated and non-activated cells. Comparing the potential of naive vs memory B cells for Type 1 cytokine production showed that CD40 ligation induced p40 IL-12, especially in memory cells ; neither subset secreted significant amounts of p70 IL-12. Memory B cells also expressed more p19 IL-23 mRNA with the major signal responsible for its production being BCR triggering. Thus, while B cell subpopulations seem to be limited in their capacity for initiating Type I responses, memory B cells exhibit the potential for their maintenance and amplification.

B cells

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