HS1

Abstract

B The hypersensitive site 1 (HS1) protein associates with Lyn kinase, a member of the nonreceptor Src family of tyrosine kinases and is rapidly phosphorylated after cross-linking of the Bcell antigen receptor, the Tcell antigen receptor, and type 1 Fcɛ receptors. This chapter presents a study in which the development of lymphoid cells in HSl-deficient mice appeared normal. Proliferative responses of splenic B and T cells after cross-linking of antigen receptors, and antibody production to T-independent antigen were impaired in HS1–/– mice. B cells in the peritoneal cavity of mutant mice were not triggered to undergo apoptosis in response to multivalent cross-linking of the antigen receptor. HS1-deficient mice when crossed with mice harboring transgenes encoding the α and β chains of Tcell antigen receptor against a male H–Y antigen resulted in progeny that demonstrated a significant defect in thymic negative selection. This study shows that HSl is involved in the antigen-receptor-derived signaling pathways and plays important roles in clonal expansion nd clonal deletion of B and T cells,