At day 28 following infection, when gradual expulsion of the adult worm has begun in BALB/c mice, striking reductions in both egg and adult worm numbers were observed in IL-6−/− hosts, compared with those of their BALB/c counterparts (Fig. 1D and E) and although granuloma numbers had decreased in frequency in both strains, there remained significantly more in the IL-6−/− host, correlating with elevated Th2 responses in these mice (data not shown). This evidence concerns the gene IL6 and infection.