[Comparative dose-effect relationship of a tuberculin standard on guinea pig sensitivity, using living and dead...

The sensitization of guinea pigs utilized for tuberculin titration may be obtained by a BCG primo-vaccination followed by an inoculation of live, virulent Myc. tuberculosis. This method, which results in a sub-evolutive form of tuberculosis, gives a satisfactory sensitization level but has the disadvantage of utilizing animals which are germ carriers and therefore dangerous. A method has been tested employing killed germs (Jamaica strain) coated with Freund's complete adjuvant H37Ra which utilizes animals presenting no danger in handling. The results of 105 titrations made on 453 guinea pigs during two years show that the reactions obtained are clear, easy to read and remain stable over a long period (F equals 0.1). The comparison of values thus obtained shows that in the case of killed bacilli in relation to live bacilli: the mean dimensions of the reaction with 5, 10 and 20 IU are significantly more important (P is less than 0.0001) and the dose-response slope is significantly steeper (P is less than 0.01) which offers more precise results. Sensitization by killed germs therefore offers the double advantage of handling non-dangerous animals and obtaining results which are more precise and easier to read.