Paroxysmal cold hemoglobinuria.

The clinical and hematological features of a rare autoimmune disorder, PCH, are reviewed. Based on the case reports of 24 patients suffering from this disease, the presence of cold hemolysins in the sera of these patients as the main cause for the red cell destruction following exposure to cold is further discussed. However, recent electron microscope and biochemical studies suggest, in addition, that alterations of the red cells, and especially of their membranes, may play a role in the hemolytic process. The role of other factors, such as thermal range, specificity, and the immunological properties of the Donath-Landsteiner antibodies, as well as the role of the complement in the cold and warm phase of the Donath-Landsteiner reaction, is discussed. The differential diagnosis between PCH and the closely related CHD is outlined. While most of the reports deal with the mechanism of red cell destruction, relatively little attention is given to the treatment of the disease. It appears that the oldest remedy, i.e., warming of the patient and prevention of his exposure to cold, remains the best.