Studies on the Specificity of the Cellular Infiltrate of Delayed Hypersensitivity Reactions

Abstract

Summary An autoradiographic study has been performed in an attempt to demonstrate specifically sensitized cells in delayed hypersensitivity reactions in guinea pigs. In one experiment, guinea pigs were given H3-thymidine at various times after immunization with a single antigen and all were skin tested 22 days after immunization. It was found that there was a continuous increase in the percentage of labeled mononuclear cells in skin reactions as a function of time of administration of H3-thymidine. In another experiment, guinea pigs were immunized with two unrelated antigens and given H3-thymidine in such a manner as to label cells proliferating in response to the first, but not the second antigen. No difference was detected in the percentage of labeled infiltrating mononuclear cells at skin reactions elicited simultaneously with each antigen at separate sites. These observations demonstrate that the specifically sensitized cells which are believed to initiate the inflammation of delayed hypersensitivity reactions are too few to be detected by the methods available.