Etiology and pathogenesis of acquired hemolytic anemia

Infantile cytomegalovirus-associated autoimmune hemolytic anemia

Autoimmune hemolytic anemia (AIHA) is a hematologic disorder that is rarely seen in infants and young children. Most cases are associated with viral or bacterial infection, but the immunologic events leading to hemolysis are poorly understood. We describe two infants with severe cytomegalovirus (CMV)-associated warm antibody AIHA. One case was immunohematologically analyzed and showed suggestive evidence that endogenous anti-CMV IgG antibodies were the pathogenic antibodies leading to hemolysis, implicating a possible causal relationship between AIHA and CMV infection. Both patients were ultimately treated with intravenous CMV immune globulin, with subsequent improvement. These cases suggest that investigation for the presence of CMV in infantile AIHA is warranted and that CMV immune globulin should be considered as a therapeutic option.

Intensive plasma exchange for severe autoimmune hemolytic anemia in a four-month-old infant

We report the smallest infant (7.5 kg) to receive intensive plasma exchange (52 PEs) therapy as treatment of autoimmune hemolytic anemia (AIHA). PE temporarily reduces circulating autoantibody levels and can be an effective adjunctive therapy with corticosteroids and cytotoxic drugs or other immuno-suppressants. Although his clinical course was prolonged and complicated by cytomegalovirus infection with spontaneous perforation of his colon, his recovery was complete. He has remained healthy for more than 2 years. Because of his small size, calcium gluconate was added to replacement fluids and calcium levels closely monitored. The apheresis machine and tubing were routinely primed with red blood cells and FFP substituted for 5% human albumin during the second half of all procedures to maintain adequate levels of procoagulant. Our experience suggests that intensive PE is helpful in controlling severe AIHA and should be considered even for very small patients.

The acute infection-associated hemolytic anemia of childhood: immunofluorescent detection of microbial antigens altering the erythrocyte membrane

The majority of acute infection-associated hemolytic diseases of infancy and childhood have been suggested to be caused by exogenic alterations of the erythrocyte surface, though laboratory methods for their further evaluation were not yet available. Investigating 96 children, the present study characterizes 72% of cases as corresponding to this type of acute acquired hemolytic anemia, which cannot be clearly related to autoantibodies against unmodified components of the host's own red cells. Using a new immunofluorescence test, the erythrocyte membrane of 80% of these children was found to be altered in vivo by nonspecific adsorption of foreign material released from the infectious micro-organisms. In 24% of cases additive binding of complement was detectable by an antiglobulin test. Thus, the adsorption of microbial antigens to the red cell surface is suggested to be one of the causes for the removal of altered erythrocytes due to phagocytosis or a complement-dependent destruction during the course of infection-associated hemolytic anemia. Especially in childhood, the immunofluorescent detection of an erythrocyte sensitization in vivo provides a further characterization of this type of mostly transient hemolytic disease, which probably can be treated without any immunosuppressive drug, merely by elimination of the underlying infection.

Severe haemolytic anaemia due to cold anti-'i' antibodies associated with cytomegalovirus infection

A 66 year old patient with multiple myeloma and monoclonal cryoglobulinaemia who developed a severe haemolytic anaemia following a cytomegalovirus infection is reported. The presence of a high titre of anti-'i' cold antibody of IgM subclass is demonstrated. Anti-'i' antibody disappeared when complement-fixation antibody titres against cytomegalovirus decreased. Various pathogenetic mechanisms involved in the development of haemolytic anaemia associated with cytomegalovirus infection are discussed. To our knowledge, this is the first case described in the English language publications associating severe haemolytic anaemia with an anti-'i' antibody after a cytomegalovirus infection in an immunocompromised patient.

Autoimmune haemolytic anaemia in childhood associated with non-complement binding IgM autoantibodies

Red cell bound IgM autoantibodies free of associated IgG autoantibodies and unable to activate complement have not yet been considered as the cause of autoimmune haemolytic anaemia (AIHA). We report on warm type AIHA resulting from the action of IgM autoantibodies on circulating RBC. Twelve children (eight of whom were infants) with relatively severe haemolytic anaemia were studied. Whereas the clinical findings and courses of all children appeared to be compatible with warm type AIHA, the serological findings during the haemolytic phase were atypical in that the direct antiglobulin test (DAT) was negative in 11, and positive in one case due to C3d only. The use of radiolabelled antihuman globulin antibodies showed, however, that the RBC of all the patients were sensitized with warm IgM antibodies. Elevated values of IgA and/or IgG immunoglobulins on the patients' RBC were found to be present in only two cases. Complement activation by IgM autoantibodies could not be detected in all other cases neither in vivo nor in vitro. Thus, we conclude that non-complement binding IgM autoantibodies were responsible for the AIHA in the majority of these children possibly representing an as yet unrecognized variant of warm type AIHA.

Autoimmune hemolysis: a critical review

Autoimmune hemolysis is defined as a shortening of erythrocyte lifespan due to antibodies directed against the individuals own red cells. This autoantibody production (by B lymphocytes) is thought to result from deficient activity of suppressor T lymphocytes. The rate of erythrocyte destruction depends on the properties of the autoantibodies and on the activities of the complement and mononuclear phagocyte systems: anemia results when destruction outweighs marrow production. Autoimmune hemolysis, which may be primary or secondary, is classified into "warm," "cold," and "mixed" types. The hemolysis associated with pregnancy. Donath-Landsteiner antibodies, of mixed type, and in children, is treated in detail. Current treatment is with immunosuppressive drugs, surgery, and plasma exchange, though immunomanipulation may become important in the future; blood transfusion may be a life-saving adjunct to other therapy.

Encephalopathy and fatty metamorphosis of the liver associated with cold-agglutinin autoimmune hemolytic anemia

Three patients with encephalopathy clinically indistinguishable from Reye syndrome but associated with elevated cold-agglutinin titers and antiglobulin-I autoimmune hemolytic anemia are reported. The patients were treated with exchange transfusions, dexamethasone, controlled hyperventilation, and intracranial pressure monitoring. Liver biopsy specimens in two of the three patients showed fatty infiltration of the hepatocytes, but the light microscopic and electron microscopic appearance of the liver was not typical for Reye syndrome. These patients are reported to alert physicians to a metabolic encephalopathy in children which mimics Reye syndrome, but is distinctly different in clinical course and complicated by cold agglutinins and an autoimmune hemolytic anemia.

Cytomegalovirus-induced haemolytic anaemia after cardiac surgery

A patient, who underwent aortic valve replacement, developed a transient, autoimmune haemolytic anaemia in association with a significant rise in titre of antibodies against cytomegalovirus. A serological survey of blood donors indicated that the source of infection was fresh blood transfused during and shortly after surgery. A number of cases of short-lived haemolytic anaemia after large volume blood transfusion with cardiac surgery may be explained by this mechanism. It may be preferable to use only blood that has been screened for evidence of recent cytomegalovirus infection if post-perfusion complications of this disease are to be avoided.

Autoimmune disease: the consequence of deficient T-cell function?

The age-related decrease in T-lymphocyte function is discussed in relation to the onset of autoimmune disease. It is postulated that the decrease in T-cell "immune surveillance" permits: a) the ingress of viruses whose enzymes modify host glycoproteins and render them immunogenic, and b) the replication of viruses incorporated into the genome of cells during infections in early life. The existence of immunodeficiencies too subtle to be detected by our present laboratory methods is postulated and discussed in relation to diseases observed in geriatric patients. It would seem that the prevention of some geriatric diseases should begin in the pediatrician's office.

[Chronic pseudomalignant immuneproliferation (Canale-Smith syndrome) (author's transl)]

A case of chronic lymphadenopathy and splenomegaly existing over a period of 11 years, with a variety of acquired deficiencies of immunity and autoimmune phenomena, is described. It is almost identical with the 5 children reported in 1967 by Canale and Smith as a new benign syndrome "chronic lymphadenopathy simulating malignant lymphoma". The relationship to similar disorders with lymphadenopathy and immunological abnormalities is discussed.

Isoimmune haemolysis in pathogenesis of anaemia after cardiac surgery

A patient who had received multiple transfusions developed antiglobulin-positive haemolytic anaemia due to a delayed haemolytic transfusion reaction. Many cases of haemolytic anaemia after cardiac surgery could be explained on this basis.

Latent cytomegalovirus infection in blood donors

Twenty-one out of 32 apparently healthy blood donors aged 21 to 65 years yielded positive complement fixation tests with a cytomegalovirus antigen, at titres ranging from 1:8 to 1:64. Virus was present in leucocyte cultures of fresh peripheral blood of two seropositive subjects from a total of 35 donors examined. Plasma and 48-hour stored blood specimens failed to disclose virus in culture. Viruria could not be demonstrated, and there was no evidence of recent illness in the study group. These findings suggest that subclinical viraemia is not uncommon in blood donors.

Cytomegalic inclusion-body disease associated with acquired autoimmune haemolytic anaemia

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