Abstract
Purified tuberculin ("sensitin") has been prepared from 16 strains of acid-fast bacilli. The specificity of the preparations was studied by comparative intradermal tests in guinea pigs sensitized with the 16 strains. No difference was found in the specificity of tuberculin prepared from BCG and from 4 strains of human virulent tubercle bacilli. The specificity of tuberculin from 3 bovine strains was essentially the same as that of the human tuberculins. The specificity of 3 avian tuberculins was different from that of the mammalian preparations. No differences were seen between the 3 avian preparations. Sensitin from Mycobacterium balnei and from 4 other acid-fast bacilli, including one strain of Mycobacterium smegmatis, showed specificities which were different from each other and from that of mammalian and avian tuberculins.