Interleukin-5 transgenic mice show augmented resistance to Angiostrongylus costaricensis infection

To determine the possible role of eosinophils in(-) Angiostrongylus costaricensis infection, both interleukin-5 (IL-5) transgenic (Tg) and non-transgenic (non-Tg) C3H/HeN mice were infected with A. costaricensis third-stage larvae. IL-5 Tg mice demonstrated greater resistance than non-Tg mice to A. costaricensis, as shown by lower adult worm recovery, smaller adults, fewer eggs in the intestinal wall and fewer larvae passed in the feces. Both mice showed similar antigen-specific IgA and IgG1 antibody responses, although IgA was more prominent than IgG1. Egg deposition and inflammatory responses in the intestinal walls were milder in IL-5 Tg mice than in non-Tg mice. The eggs with developed larvae, deposited in the intestinal walls of IL-5 Tg mice, were surrounded by numerous degranulating eosinophils and sometimes with Splendore-Hoeppli deposits. The data suggest that eosinophils are involved in the resistance of the mouse during primary infection with A. costaricensis.