CTLA4 and infection: This finding is consistent with previous studies examining the immune effects of hookworm in infected individuals living in endemic areas.13,14 Importantly, CTLA-4+ Tregs can downregulate Th1 and Th17 mediated inflammation indicating this as a possible mechanism through which hookworm could prevent or treat inflammatory diseases.15 In the current study, an increase in CTLA-4 expression was observed only in the acute infection phase before returning to baseline levels in the chronic infection phase.