IL5 and infection: To determine the role of antigen – persistence in the regulation of Th2 subsets in filarial infections, we measured the frequency of IL-5−Th2 and IL-5+Th2 cells in a subset of INF individuals (n = 9), who had been treated with anti-filarial chemotherapy and as a result had eliminated infection (as demonstrated by the absence of circulating filarial antigen) or those who had been treated but continued to harbor infection (n = 7).