Abstract
Summary
1. Comparison has been made in guinea pigs of ability of BCG and various extracts and fractions of the tubercle bacillus to stimulate increased resistance to tuber culosis. 2. Significant resistance was induced by 1 mg of BCG, given subcutaneously, in each of 4 experiments reported. 3. Comparable resistance was induced by 0.1 mg (in adjuvant) of a crude chloroform extract, and also by tubercle bacilli which had been exhaustively extracted with neutral organic solvents. 4. The immunizing potency of such defatted bacilli was completely destroyed by extraction with alcohol-ether containing 3% HCl and only partially by autoclaving for 20 minutes. The ability of defatted bacilli to induce delayed hypersensitivity was also destroyed by removal of firmly bound lipids with alcohol-ether containing HCl.
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