The Immune Response in the Presence of Delayed Hypersensitivity or Circulating Antibody

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Abstract
Summary: A specific anamnestic response to the hapten of a hapten-protein conjugate develops if delayed hypersensitivity to the protein, such as that produced by sensitization 10 days earlier with 1 µg of hen egg albumin in saline, is present at the time of challenge with the conjugate. A specific depression of the immune response to the hapten of a hapten-protein conjugate occurs if circulating antiprotein antibody, such as that resulting from sensitization 10 to 15 days earlier with hen egg albumin in Freund's incomplete adjuvant, is present. This specific suppression is not effected by administration of large amounts of passive antiprotein antibody or by concomitant injection of large amounts of protein antigen in saline. Little or no specific serologic reaction between the hapten-protein conjugate used in this study and anti-protein antibody could be detected with various in vivo and in vitro techniques. A specific anamnestic response to the hapten of a hapten-protein conjugate occurs if a preliminary injection of the protein in Freund's complete adjuvant is given 15 days prior to injection of the conjugate. Skin tests with the hapten-protein conjugate indicate that animals sensitized with protein in Freund's incomplete adjuvant develop a transient phase of delayed hypersensitivity to the conjugate which disappears coincidentally with the appearance of circulating anti-protein antibody. In contrast, animals sensitized with protein in Freund's complete adjuvant demonstrate a persisting state of delayed hypersensitivity after the appearance of circulating antibody.