Apparent increased sensitivity of mice to tuberculin by adding a non-specific inflammatory agent to the antigen.

The delayed-type hypersensitivity (DTH) reaction at the site of tuberculin injection in immunised animals depends on the presence of sentisitised T-lymphocytes which interact with the antigen and recruit non-specific phagocytic cells. The intensity of DTH reaction was found to be related to the non-specific inflammatory stimulus created by antigen injection. The early plasma protein extravasation which occurred 0.5 of an hour after antigen injection was correlated with the intensity of DTH reaction measured 18 hours later. The addition to tuberculin of a non-specific inflammatory agent (concanavalin A or sheep red blood cells) in a dose range without clinical inflammatory effect increased the apparent potency of tuberculin by a factor 1000.