Autoimmune hemolysis: mixed warm and cold antibody type

25 patients with mixed autoimmune haemolysis are described; in these cases the combined criteria for warm antibody autoimmune haemolysis and also the cold agglutinin syndrome were present. The direct antiglobulin tests were positive with IgG and complement coating of the red cells. The IgM and IgG components could be separated. The cold autoantibodies were active at 30 degrees C or above and often showed blood group specificity within the Ii system; specificity was not usually evident in the warm component. Haemolysins were found in 18 patients. Serologically, the condition maintained its mixed nature throughout; only 2 cases later changed to a warm type picture. Mixed autoimmune haemolysis was found in all age groups but was more frequent in later life; the male:female ratio was 1:15. The cases were either idiopathic (44%) or secondary; in the latter, systemic lupus erythematosus or lymphoma were the most frequently associated disorders. The patients tended to have severe haemolysis which, although usually responding well to treatment, ran a chronic course with intermittent exacerbations, thus making overall management difficult; plasma exchange may be a useful adjunct to chemotherapy.