Stability of mammalian tuberculin PPD.

Six lots of PPD prepared in 1937 met the requirements when tested in guinea pig potency assay in 1974. Reading of the skin reactions at 48 hr gave more consistent results than the 24 hr reading. Data were evaluated by analysis of variance and by a quick method developed for the estimation of identity of the standard and the test preparation. Although less sensitive than the analysis of variance, the quick method has been found suitable for estimation of the potency of tuberculin preparations.     

Assessment of tine tuberculin test.

Mantoux (10 tuberculin units) and tine tuberculin tests were performed in 190 subjects and the results recorded at 48, 72, and 96 hours. Altogether 1010 readings were recorded. Of these, 555 (55%) were Mantoux-test positive and 525 (52%) tine-test positive. While the tine test is marginally less sensitive, its advantages are simplicity and ease and speed of application. It thus provides a useful screening test for eliciting tuberculin sensitivity.     

Specificity of antigenic fractions of tuberculin.

Purified protein derivative from Mycobacterium bovis was separated into 6 fractions by electrophoresis at 1500 V/40 mA in pH 4.2 acetic acid-pyridine buffer. Further purification of one of the fractions on Sephadex G 25 column and by acid hydrolysis yielded antigen "PS" eliciting tuberculin reaction only in animals vaccinated with M. bovis BCG but not in those sensitized with M. avium and some fast-growing mycobacteria. The specificity of antigen "PS" was confirmed in vitro: the antigen induced blastic transformation only in lymphocytes of guinea pigs sensitized with M. bovis BCG.