The CD28/B7 pathway: a novel regulator of plasma cell function.

The CD28/B7 pathway is pivotal for the activation, optimal function, and regulation of T cell function. While the CD28 receptor and its ligands B7.1/B7.2 are also expressed on plasma cells, little is known of the role of the CD28/B7 pathway in plasma cell function. In this chapter we discuss the recent studies that have examined the role of CD28 expression on plasma cell function. Both stimulatory and inhibitory effects of CD28 on plasma cells have been reported. Based on our findings we propose that under homeostatic conditions the CD28/B7 interaction mediates regulation of plasma cell function whereas during inflammation this pathway can be perturbed to ramp up Ab production from existing plasma cells.