CD4+ T helper (TH) cells, particularly TH1 cells, play an important role in immunity against malaria by producing IFN-γ, which activates macrophages.280,281 Both experimental and clinical studies have shown the importance of early IFN-γ production in controlling Plasmodium replication,282,283 although the precise protective mechanisms are still not fully understood. This evidence concerns the gene IFNG and malaria.