Ablation of eosinophils with anti-IL-5 antibody enhances the survival of intracranial worms of Angiostrongylus cantonensis in the mouse

Effects of depressed eosinophilia on the development of Angiostrongylus cantonensis in the mouse were studied using monoclonal rat anti-mouse-interleukin-5 antibody (anti-IL-5). The administration of anti-IL-5 strongly depressed peripheral, cerebrospinal fluid (CSF) and medullary eosinophilic responses in mice infected with A. cantonensis, when compared with groups treated with phosphate-buffered saline solution (PBS) alone or isotype-matched rat IgG. There was no significant difference in A. cantonensis antigen specific IgG and IgE antibody responses between rat IgG treated and anti-IL-5 treated mice. Intracranial worm recovery in anti-IL-5 treated mice was consistently high throughout the course of the study and some worms migrated from the brain to the lungs. By contrast, almost all the intracranial worms in the mouse groups treated with PBS alone or rat IgG died before day 32. These data clearly indicate that IL-5 is essential for eosinophil responses in A. cantonensis infected mice and also that eosinophils serve as a potential effector cell in the killing of the intracranial worms in mice.