Delayed Hypersensitivity, Macrophage Migration, and Antibodies in Guinea-Pigs Immunized with Diphtheria Toxoid

Guinea-pigs were immunized with diphtheria toxoid (DT) in Freund's complete adjuvant (FCA) and boosted three times with DT in saline. Boosting increased anti-DT passive haemagglutinins, haemolysins, and cytophilic antibody on the surface of peritoneal exudate cells, but skin reactions to DT became negative and peritoneal cell migration was no longer inhibited by DT. When normal peritoneal cells were incubated in the sera of boosted animals, their migration was not inhibited by antigen, although they had cytophilic antibody on their surface as shown by rosette formation.