Differential roles for Wiskott-Aldrich syndrome protein in immune synapse formation and IL-2 production

Wiskott-Aldrich syndrome protein (WASP)-deficient T cells exhibit defects in IL-2 production that are widely believed to stem from primary defects in actin remodeling and immune synapse formation. Surprisingly, however, we find that WASP-deficient T cells responding to Ag-specific APCs polymerize actin and organize talin and PKCtheta normally, forming an immune synapse that is stable for at least 3 h. At low doses of peptide, WASP-deficient T cells show less efficient talin and PKCtheta polarization. Thus, although WASP may facilitate immune synapse formation at low peptide concentrations, WASP is not required for this process. Defects in IL-2 production are observed even under conditions in which immune synapse formation proceeds normally, suggesting that the role of WASP in regulating IL-2 production is independent of its role in immune synapse formation.