SLAM/ SAP signaling positively regulates the differentiation of TH17 cells and experimental autoimmune encephalitis (163.15)

Abstract

Abstract Mutations in SAP (SLAM-associated protein) underlie the majority of cases of X-linked lymphoproliferative disease (XLP), a rare congenital disorder that often leads to fatal complications upon infection with Epstein-Barr virus. The small SH2-containing adaptor SAP transmits signaling via SLAM (signaling lymphocytic activation molecule) family receptors and has been shown to be critical for development and function of multiple immune cell types. Here, we have investigated the role of SLAM and SAP signaling in regulating the differentiation of naïve CD4 T cells into IL-17 secreting effectors (TH17 cells), a pro-inflammatory lineage implicated in host defense as well as autoimmune diseases. T cell receptor activation along with co-stimulating SLAM antibodies was found to augment TH17 cell differentiation in wild type but not SAP-deficient splenic T cells under IL-17 polarizing conditions. Furthermore, SAP-/- mice were protected from experimental autoimmune encephalomyelitis (EAE), exhibiting greatly decreased numbers of CNS-infiltrating TH17 cells and dramatically reduced disease severity. Collectively, these results suggest that SLAM-SAP interactions promote the differentiation of IL-17 secreting effector CD4 T cells both in vitro and in vivo.