Analysis of TNF-a and IL-10 gene polymorphisms in Zimbabwean children exposed to malaria

Single nucleotide polymorphisms within the cytokine genes, TNF-a (-308 G/A), and IL-10 (-1082 A /G and -819 T/C) associated with protection and susceptibility to parasitic infections were examined in samples from school aged children in the Eastern district of Zimbabwe. Whole blood specimens were obtained from 491 children between the ages of 5 – 16 years, of which 26.9% were infected with Plasmodium falciparum and 73.1% were not infected. Genotyping was carried out using the amplification refractory mutation system-polymerase chain reaction (ARMS-PCR). The prevalence of TNF-agenotypes GG, GA and AA associated with low, intermediate and high cytokine production was 80, 19 and 2%, respectively. Wild type alleles TNF-α -308G* predominated in both infected and uninfected individuals in the study. For IL-10 (position -819) the distribution of wild-type alleles CC*, heterozygotes and mutant carriers TT* was 64, 27 and 9%, respectively, and a similar analysis of the polymorphisms on position -1082 for IL-10 revealed that most of the samples were heterozygotes (95%). There was no statistically significant difference in the frequencies of polymorphisms on TNF-a (-308G/A) (X2 = 1.820; p = 0.403), IL-10 (-1082 A/G) (X2 = 0.242; p = 0.623) and IL-10 (-819C/T) among children infected with P. falciparum and those without infection. Finally, the high prevalence of heterozygotes would suggest moderate to high IL-10 responses in the population analyzed and that an anti-inflammatory environment dominates when faced with acute P. falciparuminfection in the samples analyzed.   Key words:  Polymorphism, cytokines, Plasmodium falciparum, malaria.