Direct Coombs antiglobulin reactions in Gambian children with Plasmodium falciparum malaria. I. Incidence and class specificity.

Gambian children with past or present Plasmodium falciparum malaria were investigated for the incidence of Coombs positivity using monospecific antisera. Approximately 50% were positive and the most frequent form of erythrocyte sensitization was with C3d. Other specificities, EIgG, EIgGC3d and EIgGC4bC3d were less common. Erthyrocytes were never found sensitized with IgA or IgM. There was no correlation between a positive test and age, tribal status or level of parasitaemia at presentation, although a positive test was often found in association with anaemia. Sensitized erythrocytes were present in the circulation for a period of up to 6 weeks following initial observation. The mechanism of erythrocyte sensitization is not known, but the results suggest a Type III complex-mediated hypersensitivity involving parasite antigen-antibody complexes. It is likely that these reactions contribute to the pathogenesis of the anaemia in falciparum malaria.