Delayed cutaneous hypersensitivity in the dog: reaction to tuberculin purified protein derivative and coccidioidin.

A quantitative skin test for delayed-type hypersensitivity was developed in the dog. The test procedure involved testing animals in the pinna of the ear and quantitating the reaction by measuring the change in ear thickness. Skin test reactions to tuberculin-purified protein derivative and coccidioidin were found to be specific and to correlate with the immunization histories of the 27 dogs tested. Kinetic studies on the tuberculin reaction indicated that ear thickness increased slowly following antigen injection, reaching a peak at about 48 hours. Cellular infiltrates at reaction sites were primarily responsible for the increase in ear thickness. They consisted predominantly of mononuclear cells, although a marked number of neutrophils were also present. Multiple skin tests with tuberculin-purified protein derivative and coccidioidin on 8 nonimmunized (normal) dogs indicated that a skin test was capable of actively sensitizing a portion of the animals tested.