The effect of dapsone-pyrimethamine on immunoglobulin concentrations in malaria chemoprophylaxis.

Immunoglobulins IgG, IgM, IgA were estimated on 3 occasions in 59 male volunteers who were taking dapsone-pyrimethamine once weekly (dapsone: 100 mg + pyrimethamine: 12.5 mg) for malaria chemoprophylaxis. Immunoglobulins IgG and IgM measured at the 7th week of chemoprophylaxis were significantly lower than baseline values (using Students' t-test for paired data), but none of the values were below 700 mg% for IgG or 30 mg% for IgM. Immunoglobulin concentrations estimated in 45 of the 59 men 6 weeks after discontinuation of chemoprophylaxis showed a return to baseline for IgM but not IgG, which remained low. On all 3 occasions there was no significant change in the IgA concentrations. The clinical implication of these findings is not known. Further studies are required to define the effects of antimalarial drugs on the antibody response to infection and immunization.