However, adult H. polygyrus burdens 28 d post infection, and egg output at days 14 and 28 post infection, were similar between IL-1R1−/− and wild-type C57BL/6 mice (Fig. 6B–D), suggesting that heightened granuloma formation does not contribute to increased parasite expulsion and that the phenotype of IL-1R1 deficiency is not as profound as that reported for mice lacking IL-1β (34). This evidence concerns the gene IL1B and infection.