The Rac2 Guanosine Triphosphatase Regulates B Lymphocyte Antigen Receptor Responses and Chemotaxis and Is Required for Establishment of B-1a and Marginal Zone B Lymphocytes

摘要

We have defined roles for the hemopoietic-specific Rho guanosine triphosphatase, Rac2, in B lymphocyte development and function through exmination of rac2~-/- mice. Rac2-deficient mice displayed peripheral blood B lymphocytosis and marked reductions in peritoneal cavity B-1a lymphocytes, marginal zone B lymphocytes exhibited reduced calcium flux following coligation of B cell AgR and CD19 and reduced chemotaxis in chemokine gradients. T cell-independent responses to DNP-dextran were of reduced magnitude, but normal kinetics, in rac2~-/- mice, while T-dependent responses to nitrophenyl-keyhole limpet hemocyanin were subtly abnormal. Rac2 is therefore an essential element in regulating B lymphocyte functions and maintaining B lymphocyte populations in vivo.