Interferon-gamma responses are associated with resistance to reinfection with Plasmodium falciparum in young African children

The contribution of T cell-mediated responses was studied with regard to re sistance to reinfection in groups of Gabonese children participating In a p rospective study of severe and mild malaria due to infection with Plasmodiu m falciparum. In those admitted with mild malaria, but not in those with se vere malaria, production of IFN-gamma by peripheral blood mononuclear cells (PBMC) in response to either liver-stage or merozoite antigen peptides was associated with significantly delayed first reinfections and with signific antly lower rates of reinfection. Proliferative or tumor necrosis factor re sponses to the same peptides showed no such associations. Production of int erferon-gamma by PBMC in response to sporozoite and merozoite antigen pepti des was observed in a higher proportion of those presenting with mild malar ia. Differences in the Th1/Th2 cytokine balance may be linked. to the abili ty to control parasite multiplication in these young children, helping to e xplain the marked differences observed in both susceptibility to infection as well as in clinical presentation.