The Relationship between Delayed Hypersensitivity and Circulating Antibody Induced by Protein Antigens in Guinea Pigs,

Summary Sensitization by injection of immune precipitates in adjuvant induces not only delayed hypersensitivity but also the steps leading to immune antigen elimination—i.e., the production of circulating antibody. It appears that during the course of immunization the delayed hypersensitive state develops first, then gives way to the Arthus type of sensitivity as antibody production is manifest. The delayed hypersensitive state may reappear after regression of the Arthus reactivity. The possibility of delayed hypersensitivity as a step leading to the production of circulating antibody is discussed. The administration of soluble antigen intravenously to sensitized guinea pigs will block the appearance of the delayed reaction to the same antigen. Soluble antigen also tends to speed up the sequence of events leading to the production of circulating antibody when given after immunization with precipitated antigen in adjuvant.