Abstract
Summary Cortisone administered to white rats while they were being immunized to Nippostrongylus muris resulted in suppression of the inflammatory response in the skins of these animals when subsequently challenged with larvae, and apparently all of the larvae successfully penetrated through this first barrier. Many, however, were trapped in a cellular reaction in the lungs, liver, and peritoneal membranes during their migrations, but a greater number matured to adults and were larger in size than in the nontreated immune controls. Rats immunized and then treated with cortisone for the first time a few days prior to the skin challenge with larvae also demonstrated some reduction in the over-all immune reaction; this was manifested by a suppression of the cellular response in the skin but not in the internal organs, and by an increased mean length of the adult worms as compared to the nontreated immune controls. However, there was no significant difference in number of adult worms developing in this group as compared to the controls. Filariform larvae incubated in serums obtained from all immunized groups, whether they had been treated with cortisone or not, showed excretory pore precipitate formation which was considerable in quantity.