High titres of anti-T antibodies and other haemagglutinins in human malaria.

The prevalence of antibodies against (i) human red blood cells (RBC) of A and B groups, (ii) trypsinized O Rh+ RBC and (iii) neuraminidase treated O Rh+ RBC were investigated both in sera of Africans from a malaria endemic area of Upper Volta and in sera of Europeans with acute malaria from a Paris hospital. An increased frequency of high titres of haemagglutinins was observed against A and B as well as O Rh+ trypsinized human RBC, thus confirming previously published results. In addition, agglutination of neuraminidase treated RBC showed that the titres were increased in about 40% of Africans studied and in about 80% of patients with acute malaria. Using agglutination with a specific anti-T lectin and inhibition with two ligands, it was found that sera of malarious patients contain high titres of antibodies directed against the T antigen of neuraminidase treated RBC. The mechanisms of appearance of high titres of autohaemagglutinins in malaria and their possible interference in the anaemia associated with this disease are discussed.