common variable immunodeficiency (CVID), a heterogeneous group of disorders characterized by hypogammaglobulinemia, decreased antibody production in response to antigenic challenge, and recurrent pyogenic infections, and often associated with hematologic and autoimmune disorders. Most patients have normal numbers of circulating B cells that can identify antigens and proliferate, but they lack plasma cells and may have an intrinsic defect of B cell differentiation. Two less common forms are also recognized, one caused by a disorder of T lymphocyte regulation and one caused by production of autoantibodies against T and B lymphocytes.
