CD4 and infection: Another key cytokine for controlling parasite-related pathology and regulating Th1 and Th2 inflammatory cytokine production is IL-10,83, 84 which is upregulated by both CD4+Foxp3− and CD4+Foxp3+ subsets following H. polygyrus infection.13 Our findings of decreased IL-10 following IL-2C treatment and increased IL-10 following Treg depletion reveal that it is unlikely that IL-10 from CD4+Foxp3− cells regulates inflammatory responses following infection with H. polygyrus.