AIOLOS REGULATES B-CELL ACTIVATION AND MATURATION TO EFFECTOR STATE

Aiolos encodes a zinc finger DNA-binding protein that is highly expres sed in mature B cells and is homologous to Ikaros. In the periphery of mice homozygous for an Aiolos-null mutation, B cells exhibit an activ ated cell surface phenotype and undergo augmented antigen receptor (BC R)-mediated in vitro proliferative responses, even at limiting amounts of stimulant. In vivo, T cell-dependent B cell responses, including t he formation of germinal centers and elevated serum IgG and IgE, are d etected in Aiolos-deficient mice in the absence of immunization. Auto- antibodies and development of B cell lymphomas are frequently seen amo ng aging Aiolos mutants. In sharp contrast to conventional B cells, B cells of the peritoneum, of the marginal zone, and the recirculating b one marrow population are greatly reduced.