Direct antiglobulin reactions in Gambian children with P. falciparum malaria. III. Expression of IgG subclass determinants and genetic markers and association with anaemia.

The IgG subclass and Gm allotype distribution of red cell-bound IgG molecules from Gambian children with past or present falciparum malaria has been determined. The results show that the antibody is polyclonal with some predominance of the IgG2 and IgG4 subclasses. A restriction towards IgG2 antibodies may indicate specificity for a schizont-derived antigen which is carbohydrate in nature. Not all the allotypes normally carried by the G3m(b) allele could be demonstrated on IgG3-sensitized cells, a finding which remains unexplained. Expression of G3m(10), (11) and (14) allotypes of the IgG3 molecule was noted. Sensitization of red cells with IgG1 molecules correlated with the presence of anaemia but red cells sensitized with IgG2, IgG3 or IgG4 usually came from children with haematological findings within the normal range for that population. The implications of the results are discussed with reference to the few reports on the subclass and Gm allotype of malaria-specific IgG.