Enzymatic Determination of in vitro Lysis of Leukocytes by Tuberculin

Abstract

Guinea pigs were rendered hypersensitive to tuberculin by the intramuscular injection of heat-killed Mycobacterium tuberculosis (Hg37Rv). Peripheral blood leukocytes from normal and sensitized animals were incubated at 37[degree] C for 2 hours in the presence and absence of purified protein derivative (PPD). After incubation, leukocyte lysis by PPD was measured by microscopic leukocyte counts and by a method based on the release of an intracellular, lysozyme-like, enzyme from lysed leukocytes. The comparision of in vitro tuberculin cytolysis measured by both methods indicated that the lysozyme assay method was an adequate measure of leukocyte lysis and an acceptable substitute for microscopic cell counts. The relative speed and simplicity of the enzyme assay method add to its applicability.