DESENSITIZATION OF DELAYED-TYPE HYPERSENSITIVITY IN MICE - SUPPRESSIVE ENVIRONMENT

THE systemic injection of high doses of antigen into a preimmunized an imal results in transient unresponsiveness of cell-mediated immune res ponses. This phenomenon is known as desensitization. Serum interleukin 2 (IL-2) activity was found transiently in desensitized mice at 3 h a fter the antigen challenge. These mice could not reveal antigen nonspe cific delayed-type hypersensitivity (DTH) 1 d after the challenge. Spe cific suppression of DTH was observed at later stages. Sera from 3 h d esensitized mice showed suppressive effects on DTH in pre-immunized mi ce. Administration of recombinant IL-2 into preimmunized mice led to t he failure of development of DTH to antigens. These observations sugge st that IL-2 plays an important role in the suppressive environment.