Our findings indicate that the genetic interaction between these two IL-4 variants is a key factor of SM susceptibility, probably because of its direct role in IL-4 regulation.
FBAT analyses showed that the most significant association was between the IL4 variable-number tandem repeat (VNTR) 1/2 genotype and SM (P < .001); an association was also observed for IL4-33 C/T, rs2243267 G/C, rs2243268 C/A, and rs2243282 C/A (P < .05).
The IFN-gamma levels were significantly elevated in patients with complicated malaria in the initial stage of the disease before treatment compared to the levels found with uncomplicated malaria (231pg/ml versus 150pg/ml, p=0.0029), while the IL4 levels were significantly elevated 7 days after treatment (167pg/ml versus 81pg/ml, p=0.0003).
These results raise the possibility that there is a relationship between susceptibility to severe malaria, IgE production and genetic variation in the IL4 region, which merits further investigation in other epidemiological settings.
The IL-13 -1055T allele showed a significant association with protection from severe malaria (OR 0.51, 95% CI 0.32-0.80; P=0.0032 by the chi(2) test), while allele frequencies of IL-3 -16T>C and IL-4 -590T>C were not statistically different between mild and severe malaria patients.