We have used the
complement-fixing antibody consumption ( CFAC ) test to detect small concentrations of
IgG on red blood cells from patients with hemolytic
anemias that are not thought to be caused by an immune mechanism. Although patients with
hereditary spherocytosis,
pyruvate kinase deficiency, and mechanical hemolytic
anemias generally had normal concentrations of
IgG bound to their red cells (less than 25 molecules
IgG per red cell), we found that 39/62 (63%) patients with
sickle cell anemia had elevated values. These 39 patients had a mean of 195 and a maximum of 890 molecules of
IgG per red cell. None of the patients had been transfused within the previous 90 days, and some had never been transfused. Direct antiglobulin tests were positive in only two instances and
autoantibodies were not found in the serum of any patient. However, eluates from the red cells of 6 of 23 patients demonstrated antibody activity against all of a panel of normal red cells by the indirect antiglobulin test. There was no correlation between the number of
IgG molecules on patients' red cells and the severity of their
anemia, the incidence of painful sickle cell crises, the reticulocyte count, or with
blood transfusion history. We conclude that further study of immunohematologic abnormalities in patients with
sickle cell anemia is warranted, especially in view of previous reports in this population of patients with red cell
autoantibodies,
autoimmune hemolytic anemia,
hemolytic transfusion reactions without detectable
alloantibodies, and an association of some episodes of
pain crises with immunologically mediated red cell destruction.