Cold haemagglutinin disease: clinical significance of serum haemolysins.

Two hundred and twenty-one patients with cold haemagglutinins of thermal amplitude > or = 30 degrees C (considered to be a reasonable indicator of clinical significance) were classified by in vitro haemolysin activity into three groups. Group 1 contained 116 individuals in whom haemolysins were never detected; the 74 patients in Group 2 had monophasic haemolysins alone; whereas both monophasic and biphasic haemolysins were detected in the 31 Group 3 patients. There was a significantly higher proportion of patients in Groups 2 and 3 with haptoglobin levels < 0.1 g/l compared with Groups 1 and 2, respectively (P < 0.005 and P < 0.001). Direct antiglobulin test results showed that the autoimmune response became more complex and IgM predominant through Groups 1-3, resulting in an increasing ability to activate complement which was reflected in increasing haemolysin activity and number of patients with active haemolysis. The 31 patients in Group 3 were mostly elderly (median age 71 years at presentation) and the majority had chronic cold haemagglutinin disease (CHAD), several in association with lymphoid neoplasms or carcinomas; only four had acute CHAD. The natural history of idiopathic chronic CHAD was of mild, well compensated haemolysis, punctuated by severe acute episodes necessitating intensive therapy. The condition often remained active for long periods and did not appear to affect natural lifespan. In some cases, no treatment (or just warmth) was needed; in others continuous or intermittent prednisolone and/or chlorambucil were effective; yet others required a greater variety and more intense therapy, or treatment of associated conditions. Blood transfusion support was frequently required when haemolysis was severe.