The src homology 2 domain-containing tyrosine phosphatase 2 regulates primary T-dependent immune responses and Th cell differentiation

The src homology 2 domain-containing tyrosine phosphatase 2 (SHP2) plays an important role in development and in growth factor receptor signaling pathways, yet little is known of its role in the immune system. We generated mice expressing a dominant-negative version of the protein, SHP2(CS), specifically in T cells. In SHP2(CS) mice, T cell development appears normal with regard to both negative and positive selection. However, SHP2(CS) T cells express higher levels of activation markers, and aged mice have elevated serum Abs. This is associated with a marked increase in IL-4, IL-5, and IL-10 secretion by SHP2(CS) T cells in vitro. In addition, primary thymus-dependent B cell responses are deficient in SHP2(CS) mice. We show that whereas TCR-induced linker for activation of T cells phosphorylation is defective, CTLA-4 and programmed death-1 signaling are not affected by SHP2(CS) expression. Our results suggest that a key action of wild-type SHP2 is to suppress differentiation of T cells to the Th2 phenotype.