Infection with Syphacia obvelata (pinworm) induces protective Th2 immune responses and influences ovalbumin-induced allergic reactions.

Infections with pinworms are common in rodent animal facilities. In this study, we show the consequence of an outbreak in a transgenic barrier facility of infection by Syphacia obvelata, a murine pinworm gastrointestinal nematode. Immune responses were defined in experimental infection studies with BALB/c mice. Infection with S. obvelata induced a transient Th2-type immune response with elevated interleukin 4 (IL-4), IL-5, and IL-13 cytokine production and parasite-specific immunoglobulin G1 (IgG1). In contrast, BALB/c mice deficient in IL-13, IL-4/13, or the IL-4 receptor alpha chain showed chronic disease, with a >100-fold higher parasite burden, increased gamma interferon production, parasite-specific IgG2b, and a default Th2 response. Interestingly, infected IL-4-/- BALB/c mice showed only slightly elevated parasite burdens compared to the control mice, suggesting that IL-13 plays the dominant role in the control of S. obvelata. The influence that pinworm infection has on the allergic response to a dietary antigen was found to be important. Helminth-infected mice immunized against ovalbumin (Ova) elicited more severe anaphylactic shock with reduced Ova-specific IL-4 and IL-5 than did noninfected controls, demonstrating that S. obvelata infection is able to influence nonrelated laboratory experiments. The latter outcome highlights the importance of maintaining mice for use as experimental models under pinworm-free conditions.