TGFB1 and infection: Malaria naïve individuals undergoing experimental P. falciparum sporozoite infection showed an increase in FOXP3 mRNA expression and expansion of Tregs 10 days after infection; Treg induction correlated with high circulating levels of TGF-β, low levels of pro-inflammatory cytokines and rapid parasite growth [27] suggesting - but not proving - that Treg activation early in infection may inhibit the development of effective cellular immunity.