Frequency of cytokine-producing T cells in patients of different age groups with Plasmodium falciparum malaria

The frequency of cytokine-producing T cells was assessed in patients of different age groups (29 infants, aged 1-5 years; 30 schoolchildren, aged 6- 14 years; 26 adults, aged >15 years) with acute Plasmodium falciparum malaria from Gabon. By using flow cytometry for the intracellular detection of cytokines, a striking expansion was seen, in adults compared with children, of CD4+ and CD8+ T cells with the following profiles of type 1 cytokine production: interleukin (IL)-2/interferon (IFN)-γ+, IL-2+/IFN-γ+, and IL-2+/IFN-γ-. Patients with hyperparasitemia had a significantly lower frequency of IL-2-/IFN-γ+ CD4+ cells: Type 2 cytokine expression (IL- 4+/IFN-γ-, IL-13+/IFN-γ-) and type 0 cytokine expression (IL-4+/IFN- γ+, IL-13+/IFN-γ+) were also increased in adults within the CD4+ subset. Frequencies of IL-5+/IL-4+, IL-10+/IFN-γ-, and IL-10+/IFN-γ+ cells were similar in all groups. The increased frequency of both type 1 and type 2 cytokine-producing T cells in adults is likely to be of significance in the protection against P falciparum malaria.