PBMCs from volunteers infected with 15 third-stage larvae (L3) of N. americanus were restimulated with NaES and showed increased antigen-specific production of the Th2 cytokines IL-4, IL-5 and IL-13, compared with PBMCs from uninfected controls, reaching a peak 12 weeks after infection (Figure 2A–C), although increases in IL-4 levels did not reach statistical significance. This evidence concerns the gene IL13 and infection.