Abnormal haemoglobins in the Sudan savanna of Nigeria. IV. Malaria, immunoglobulins and antimalarial antibodies in haemoglobin AC individuals.

Haemoglobin (Hb) AC electrophoretic pattern was found in 0.7% of the population at Garki, Kano State, northern Nigeria, an area where malaria is hyperendemic. Twenty-one Hb.AC subjects at all ages did not differ from the rest of the population in their frequency or density of Plasmodium falciparum, P. malaria or P. ovale infections, nor in their IgM concentrations and titres of specific antimalarial antibodies. However, IgG levels in Hb.AC subjects were frequently above the average of the reference population (P less than 0.05), especially during a period of protection against malaria (P less than 0.01). These observations suggest that the Hb.C gene may be maintained in certain environments by an enhanced ability to produce IgG antibodies against an antigen or antigens other than malaria, and that its geographical relationship to malaria may be a coincidence. This hypothesis needs to be tested where Hb.C is seen at high frequency, in northern Ghana and Upper Volta or Gwoza (Nigeria).