Reduction of carrageenan- bradykinin- and histamine-induced acute inflammation by experimental eosinophilia in rats.

An examination was made of the effects of eosinophilia on acute inflammation. Sprague Dawley rats were infected with Trichinella spiralis larvae which resulted in a blood eosinophilia. Groups of rats with the induced eosinophilia, and untreated rats without the eosinophilia, were treated with carrageenan, bradykinin or histamine in the hind paw to induce local inflammation. Paw oedema induced by carrageenan as a measure of the inflammation was much reduced in those rats with an eosinophilia, and slightly but significantly reduced in the site treated with histamine or bradykinin. Though other anti-inflammatory factors may have participated, it is believed that the reduction in inflammation was due to the eosinophils. Pretreatment of the rat paws with an eosinophil chemotactic factor tetrapeptide (ECF-A) caused no chemotaxis and therefore no effect on histamine-induced oedema.