Clinical and serological records of 865 patients with confirmed autoimmune haemolysis (AIH)-a much larger series than any previously reported-were critically reviewed and analysed. A proposed new classification for AIH based on serological findings differs from traditional classifications in that a new category of "mixed" AIH has been defined in which both "warm" and "cold" autoantibodies are present, and both are capable of causing haemolysis. Patients in this mixed group tend to have severe disease that may run a chronic intermittent course. The presentation of cold agglutinin disease is much more variable than has been seen in previous studies, haemolysis due to low titre autoantibodies being common. The AIH associated with pregnancy, usually considered as being of bad prognosis, is often mild and self limiting in the absence of other associated disorders.

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°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 1:1.5. 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 servere 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.

The clinico-pathological features of 42 children with autoimmune haemolysis are described. Over 65 % of cases were seen before their 5th birthday. In this group males predominated by the ratio of 2.5:1, but in the older children both sexes were equally affected. The incidence decreased from 1 in 188 × 10³ in young males to 1 in 1,780 × 10³ in children over 10. Cases were classified serologically. Of particular note was the frequency of Donath-Landsteiner haemolysis which equalled that due to warm autoantibodies; together these groups made up 79% of the total cases. Most haemolytic episodes followed an acute infection. This was frequently mild and often involved the upper respiratory tract; in only 2 patients was haemolysis associated with underlying collagenosis. Typically there was a sudden onset of pallor and malaise; jaundice, splenomegaly and hepatomegaly were found in about half the subjects. Haemoglobinuria was characteristic of Donath-Landsteiner haemolysis. The illness was severe, with Hb levels falling below 6.0 g/dl in 28 patients. Prednisolone, blood transfusion and, where indicated, antibiotics were usually effective in treating the illness, with splenectomy reserved for cases where this treatment was unsatisfactory. In several individuals no treatment was required. Recovery was rapid, and complete recovery occurred in 83 % of patients, usually within 6 months. Although 2 patients died, a generally optimistic prognosis can be given, particularly in the absence of an underlying chronic disorder.

The clinical pattern of haemolysis associated with Donath-Landsteiner antibodies has undergone a change over the years. In the current study 13 patients developed the acute form of the disease whilst only 1 presented with the classical picture of chronic paroxysmal cold haemoglobinuria. The acute illness typically occurred in young children with a male predominance of about 2.5:1; 10 patients were less than 5 years old. There.was often a history of a preceding infection, the onset was sudden, prostration, haemoglobinuria and pallor were prominent. The patients were very ill but rapid and complete recovery usually occurred within a few days; however, 1 patient died. Treatment consisted of rest and warmth; in addition blood transfusion was needed in 7 patients. The chronic disease (which was non-syphilitic in origin) followed a benign course, warmth and avoidance of cold being all that were necessary to maintain the patient’s well-being. It is felt that the general term for this disorder should be Donath-Landsteiner haemolysis rather than the traditional paroxysmal cold haemoglobinuria

The provision of blood for transfusing patients whose sera contain red cell autoantibodies requires considerable expertise. Over 8 years, 3888 samples from 2149 patients were examined; the varying clinical presentation necessitated a flexible investigative approach. The autoantibodies showed evidence of blood group specificity in 706 patients (32.9%), usually within the Rh system for warm reacting antibodies, whereas cold antibodies were mostly anti-I. Concomitant alloantibodies were detected by noting varying reaction strengths during antibody investigation and compatibility testing, and by absorption techniques using autologous or selected allogenous red cells. Alloantibodies were found in 294 patients (13.7%); the most frequent were anti-E and anti-K. Compatibility tests were performed on SAG-M donor blood of suitable ABO group, similar Rh genotype, Kell negative and lacking antigens to any alloantibodies detected. All units of blood were incompatible by at least one technique and were issued as 'not compatible but considered suitable'. A total of 7052 units was issued for 1685 patients; no haemolytic reactions were reported. It was concluded that blood can be safely given to patients with autoantibodies, even in serologically complex cases, providing adequate investigations are carried out.