Interleukin-5 Transgenic Mice Show Enhanced Resistance to Primary Infections withNippostrongylus brasiliensisbut Not Primary Infections withToxocara canis

Abstract

In this study, interleukin-5 (IL-5) transgenic mice with lifelong eosinophilia were assessed for resistance to primary infections with two tissue-invading nematodes, Nippostrongylus brasiliensisand Toxocara canis. Relative to nontransgenic littermates, three lines of IL-5 transgenic mice with varying degrees of eosinophilia all displayed enhanced resistance to N. brasiliensis. Although the timing of final worm expulsion was similar in transgenic and nontransgenic hosts, intestinal worms in transgenic mice were fewer in number throughout infection, failed to increase in size over the course of the infection, and were much less fecund. In contrast, T. canis larvae were recovered in similar numbers from tissues of transgenic mice with “low” or “high” eosinophilia and from nontransgenic mice. These results and other data suggest that eosinophils can contribute to host resistance to some parasite species. Parasite transit time through the host may correlate with relative sensitivity to eosinophils.

Murine nematode immunology in Australasia

“…Although anti-IL-5 antibody treatment can suppress eosinophilia in mice infected with T. canis, it does not increase larval load in the liver (137), an observation supported by the observation that IL-5 ) ⁄ ) mice are no more susceptible to T. canis than WT controls (138). In conjunction with Jim Parsons (Victorian Institute of Animal Science), we have shown that in IL-5 Tg mice infected with T. canis, the numbers of larvae recovered from liver, brain and muscle are comparable to those in WT littermates (64). It would seem then that T. canis is neither enhanced nor disadvantaged by eosinophilia and larvae are resistant to damage and killing by eosinophils, though these cells may contribute to lung pathology (138).…”

Persistent airway hyper‐responsiveness and inflammation in Toxocara canis‐infected BALB/c mice

“…The role of IL-5 during Toxocara infection is not clear. IL-5 does not seem to play an important role in protective immunity, since previous studies have shown that the number of larvae in tissue does not change in IL-5 transgenic compared with non-transgenic mice [20]. Other studies have shown that mice that are genetically deficient in IL-5 carry similar numbers of larvae compared with those of wild-type mice [21].…”

Strain-dependent resistance to allergen-induced lung pathophysiology in mice correlates with rate of apoptosis of lung-derived eosinophils

“…Eosinophils are often a prominent feature of the inflammatory infiltrate in the tissues and the lumen of airways of asthmatics [1,2]. Eosinophils play a beneficial role in immunity to some species of parasitic worms [3][4][5] and may contribute to host defense against respiratory viruses (reviewed in ref. [6]).…”