CD72-deficient mice reveal nonredundant roles of CD72 in B cell development and activation

CD72, a B cell surface protein of the C-type lectin superfamily, recruits t he tyrosine phosphatase SHP-1 through its ITIM motif(s). Using CD72-deficie nt (CD72(-/-)) mice, we demonstrate that CD72 is a nonredundant regulator o f B cell development. In the bone marrow of CD72(-/-) mice, there was a red uction in the number of mature recirculating B cells and an accumulation of pre-B cells. In the periphery of CD72(-/-) mice, there were fewer mature B -2 cells and more B-l cells. In addition, CD72 is a negative regulator of B cell activation, as CD72(-/-) B cells were hyperproliferative in response to various stimuli and showed enhanced kinetics in their intracellular Ca2 response following IgM cross-linking.