Tubercle bacillary extracts immunogenic for mice: 1. Factors affecting demonstration of their activity

Abstract

Improved methods have been developed for studying tuberculo-immunity in mice, particularly in connection with using the lung density technique to measure tuberculosis. The unique value of this method for assessing and distinguishing two phases in the pathogenesis of mouse tuberculosis is illustrated by some of the findings reported in this paper. Several effects on mouse tuberculo-immunity of killed tubercle bacilli and of extracts obtained from them as immunizing antigens, of infection doses, of delayed hypersensitivity, of fatty acid ester-supplemented diets, of brief treatment with cortisone acetate, of different vaccination routes, and of adjuvants have been examined and discussed. Acetone-killed tubercle bacilli of virulent, attenuated, avirulent, human or bovine strains, and a water-soluble extract of trypsin-treated tubercle bacilli were found to be immunogenic whether injected subcutaneously or intraperitoneally, in buffer suspensions, oil suspensions, or water-oil emulsions. A bacillary protein obtained from culture medium proved to be somewhat less protective, not often showing its effect unless injected in a water-oil emulsion. Delayed hypersensitivity may account for the progression of tuberculous lung destruction in mice which cannot be accounted for at present as due solely to multiplication of invading tubercle bacilli. To a limited extent, but important to interpretation of mouse immunity experiments, the delayed hypersensitivity aspects of mouse tuberculosis could be controlled with cortisone acetate or corn oil.