Frequency of cytokine-producing CD4(-)CD8(-) peripheral blood mononuclear cells in patients with Plasmodium falciparum malaria

The frequency of cytokine-producing CD4(-)/CD8(-) mononuclear cells was ass essed in patients of different age groups (29 infants, aged 1-5 years; 30 s choolchildren, aged 6-14 years, 26 adults, aged > 15 years) with acute Plas modium falciparum malaria, from Gabon, Fifteen patients were followed up be fore antimalarial treatment (day 0), during parasite clearance (day 3) and after resolution of parasitemia (day 10), By using flow cytometry for intra cellular detection of cytokines, a striking expansion of CD4(-)/CD8(-) cell s producing the type 1 cytokines interleukin (IL)-2(-)/interferon (IFN)-gam ma(+), IL-2(+)/IFN-gamma(+) and IL-2(+)/IFN-gamma(-) was observed in adults as compared with children. Type 2 cytokine expression (IL-4(+)/IFN-gamma(- ), IL-13(+)/IFN-gamma(-)) and type 0 cells (IL-4(+)/IFN-gamma(+), IL-13(+)/ IFN-gamma(+)) were not significantly different between the three age groups . Patients with severe malaria had a significantly increased frequency of t ype 2 cytokine-producing CD4(-)/CD8(-) cells. Drug-induced clearance of par asitemia was characterized by a decrease of IL-2(+)/IFN-gamma(-) and type 2 cytokine expressing CD4(-)/CD8(-) cells and by a gradual increase of IL-10 (+)/IFN-gamma(-) expression. The tape 1/type 2 dichotomy observed within th e CD4(-)/CD8(-) cell population is likely to be of significance in the host response against P. falciparum malaria.