Schistosoma mansoni infection shows a strong increase in the number of CD4 Foxp3+ Treg cells in parallel with the Th2 response (3); however, a later study using live infection, as opposed to schistosome egg antigen challenge (3), suggested that the control of the response was not dependent on Foxp3+ T-cells but on a population of CD4+CD25−CTLA4+ IL-10-secreting cells (4). This evidence concerns the gene CD4 and infection.