Patterns of cytokine secretion by individuals living in a malaria endemic area of western Kenya

Abstract

Malaria causes a variety of immune responses in the infected host. Stimulated immunocomponent cells secrete cytokine which, although primarily play a role in immunity are also immunopathological. The severity and the nature of malaria complications depend on age and intensity of transmission. In malaria holoendemic areas, it is the young children, 6 months to 2 years who bear the brant of infections, and usually develop severe malaria complicated with anemia while adults develop some immunity. A cross-sectional study was carried out at Kombewa, a malaria holoendemic area in Western Kenya, to determine whether age-related differences exist in the pattern of cytokine secretion in malaria infection. Plasma samples were obtained from 420 study participants aged 1 month to 60 years. The participants were stratified into seven groups by age. The plasma samples were then assayed for levels of pro-inflammatory cytokines (TNF- a and IL-8) and antiinflammatory cytokines (IL-10 and IL-4) using sandwich ELISA. TNF- a concentration was highest among 13-24 months old children (73.22f37.65pg/ml) and declined steadily in the older age groups. (P<0.05). This peak corresponded with the peak in the levels of IL-10 (201.52f54.34pg/ml). The proportion of IL-10 to TNF- a was significantly lower in this age group (13-24 months) as compared to the other age groups. The levels of IL- 8 were highest at 13-24month old (68.75f20.52pg/ml) compared to the other age groups. The levels of IL-4 were undetectable in the majority of the samples. This data suggests a possible age related pattern in the secretion of both pro- inflammatory and antiinflammatory cytokines with a peak at the age of 13-24 months when the individuals are susceptible to severe malaria infection and a decline in older ages. This study has improved the understanding of roles of cytokines on malaria disease pathogenesis and its management.