PEST Domain-Enriched Tyrosine Phosphatase (PEP) Regulation of Effector/Memory T Cells

Protein tyrosine kinases and phosphatases cooperate to regulate normal immune cell function. We examined the role of PEST domain–enriched tyrosine phosphatase (PEP) in regulating T cell antigen–receptor function during thymocyte development and peripheral T cell differentiation. Although normal naïve T cell functions were retained in pep -deficient mice, effector/memory T cells demonstrated enhanced activation of Lck. In turn, this resulted in increased expansion and function of the effector/memory T cell pool, which was also associated with spontaneous development of germinal centers and elevated serum antibody levels. These results revealed a central role for PEP in negatively regulating specific aspects of T cell development and function.