A comparison of four methods for measuring cutaneous delayed- type hypersensitivity reactions to protein antigens in the mouse.

Delayed-type hypersensitivity was induced in mice by injecting keyhole limpet haemocyanin or human serum albumin in Freund's complete adjuvant. Four techniques for assessing specific skin reactions in these immunized animals were compared: increase in thickness of the footpad; increase in thickness of the ear; arrival of 51Cr-labelled syngeneic lymph node cells at the challenge site in the ear; and accumulation of (125I)IUdR at the challenge site in the ear. The most sensitive and reliable test for detecting strong and weak reactions proved to be measurement of antigen-induced thickening in the ear.