Interleukin-5 modulates eosinophil accumulation in allergic guinea pig lung

Based on its involvement in eosinophil biology, interleukin 5 (IL-5) may play a role in the pulmonary eosinophilia associated with allergic reactions. We have examined that hypothesis using a neutralizing antibody to IL-5 in ovalbumin-sensitized guinea pigs challenged with aerosolized antigen. The extent of eosinophilia has been quantitated in bronchoalveolar lavage (BAL) and by histologic evaluation of lung tissue sections. Acute intraperitoneal administration of a rat IgG, monoclonal antibody to murine IL-5 derived from TRFK-5 cells prevented lung and BAL eosinophilia in a dose-dependent fashion at and above 10 micrograms per guinea pig. Treatment with either an experimentally irrelevant, isotype-matched antibody from GL113 cells or with heat-denatured IL-5 antibody was without effect. These studies demonstrate the importance of IL-5 to pulmonary eosinophilia in challenged, allergic guinea pigs.