Effect of season of birth on cytokine/chemokine signatures.
A. Comparison of cytokine/chemokine signatures between dry and rainy seasons of birth in 30 Malawian infants. Among the 42 cytokines and chemokines measured, 3 cytokines including IFN-γ, TNF-α and IL-10 were higher in the infants who were born in the dry season compared with those born in the rainy season. Conversely, Gro production was significantly higher in infants born in the rainy season than in those with dry season of birth. B. Further analysis considering season of birth between the Malawian (n = 14) and Gambian infants (n = 24) born in the dry season demonstrated that only IL-1α, IL-1ra and IL-6 responses to M. tb PPD were significantly higher in the Gambian infants (P < 0.05, Mann Whitney test). Other cytokines including IFN-γ responses to M. tb PPD in Malawian and Gambian infants who were born in the dry season were not significantly different (P > 0.05, Mann Whitney test). The median responses to M. tb PPD are indicated in red.