Separable effector T cell populations specialized for B cell help or tissue inflammation.

We identified specialized B helper and tissue inflammatory CD4(+) T cell subsets that developed concurrently from common naïve precursors during the primary immune response. These separable populations were distinguishable by their expression of adhesion and chemoattractant receptors that directed their homing to the appropriate effector sites in vivo and also showed intrinsic differences in their ability to support B cell antibody production and produce effector cytokines in vitro. Thus, our data show a previously unappreciated functional specialization among CD4(+) effector T cells, further defining their diversity and role in adaptive immunity.