[Heteroimmune hemolytic anemia associated with antilymphocyte globulin treatment in a patient with aplastic anemia].

A 24-year-old male patient with a severe aplastic anemia (SAA) was treated with equine-antilymphocyte globulin (ALG). As complication of this treatment he developed a severe heteroimmune hemolytic anemia mediated by anti-species pan-agglutinin antibodies present in ALG. In spite of the fact that ALG is absorbed with red-cell stroma and platelets to remove anti-erythrocyte and anti-platelet contaminating antibodies, often only partial absorption is achieved, and the remaining antibodies are passively acquired by the recipient. Neutropenia and especially thrombocytopenia are usual complications of this treatment, but it is also possible to detect anti-erythrocyte antibodies in the serum and on the red cells of those patients. However, the unusual severity of the hemolysis suffered by our patient, with a striking decrease of the hemoglobin levels (Fig. 1) can be ascribed to the administration of ALG at a time at which the hematocrit was close to normal as a result of the previous administration of anabolics. It is likely that in severely anemic patients, with a high transfusional demand, such a hemolytic episode may remain undetected. The patient acquired reactivity to the direct antiglobulin test, as well as the positive results of investigation of unexpected antibodies and compatibility testing can be accounted for by the fact that commercial antihuman globulin serum (AGS) contains antibodies reacting with a globulin component shared by human and horse sera. Neutralization of AGS with ALG administered to the patient removed those cross-reacting antibodies, making it possible to perform reliable transfusion compatibility testing and to rule out the eventual presence of hidden alloantibodies or warm autoantibodies. Neutralized Coombs serum maintained its human antiglobulin properties unaltered (Table 1).(ABSTRACT TRUNCATED AT 250 WORDS)