Autoimmune hemolytic anemia in association with monoclonal IgM(κ) with anti-i activity

A patient with a warm autoimmune hemolytic anemia with an immunoglobulin G (IgG) panagglutinin, also had monoclonal IgM(κ) cold agglutinin with anti-i activity. Ninety per cent of the peripheral blood lymphocytes had surface immunoglobulin and the number of T cells was diminished. A subpopulation of the patient's lymphocytes formed rosettes with cord (I) erythrocytes and not with adult (I) erythrocytes. The finding of increased lymphocytes bearing i-binding sites and a monoclonal antibody with anti-i activity could be related to shared idiotypic determinants between antigen-binding sites and serum antibody. The occurrence of two autoantibodies in this patient suggests an immune regulatory disorder.