The tuberculin test in guinea-pigs and cattle. The allergic response of animals to tuberculin and to extracts of non-pathogenic acid-fast bacteria

Abstract

1. In guinea-pigs a sufficient degree of infection with the organism of tuberculosis can be set up by artificial means so that reactions with tuberculin are given within from 24 to 30 days. This means that the period of 6-8 weeks usually elapsing before subjects injected with suspected tuberculin material are killed for diagnosis can be shortened by testing the subject and a control, with tuberculin in from 24 to 30 days, thus expediting results of tests. 2. Animals infected with Br. abortus may give strongly suspicious reactions when tested with tuberculin. 3. Reactions strongly suspicious of positive tuberculin reactions have been observed in cattle that were pregnant and' close to the time of parturition. A similar case was observed in a control guinea-pig. 4. Guinea-pigs infected with strains of non-pathogenic acid-fast organisms gave reactions in some cases when tested with tuberculin in a dilution of 1 to 100. More marked reactions to tuberculin were obtained when lower dilutions were used, viz., 1 to 10 to 1 to 40 dilutions. 5. Extracts prepared from non-pathogenic acid-fast organisms, in the same way as tuberculin is prepared, appear to contain some antigenic factor common to all members of this , group that gives rise to reactions when inoculated into small animals artificially infected with separate members of this group. 6. Extracts prepared on the lines of L'anaexo-Tuberculin may contain products that are specific for each member of the acid-fast group of organisms. 7. Cattle up to 2½ years of age can be sensitized by the subcutaneous inoculation of 10 mg. of strains of M. butyricum and M. phlei suspended in liquid paraffin. Larger amounts of the organisms do not appear to give rise to a greater degree of sensitivity. 8. Cattle sensitized by subcutaneous inoculation of strains of M. butyricum and M. phlei gave definite suspicious reactions when tested with tuberculin by the double intradermal method. 9. These same animals when tested with avian tuberculin showed no more marked suspicious reactions than when tested with standard tuberculin. 10. Thirteen and a half months after subcutaneous inoculation with strains of M. butyricum the non-pathogenic organism M. butyricum could be cultivated from pus obtained from the resultant lesion. 11. Sections cut from the lesions set up by these two organisms showed changes indistinguishable from those set up by tuberculosis. 12. Four months after the surgical removal of the lesions set up by the inoculation of the non-pathogenic acid-fast organisms the animals still gave definite positive reactions when tested against the corresponding extracts. 13. It is probable that some non-specific reactions shown by animals, when tested with tuberculin, may be due to these animals being sensitized naturally by a strain or strains of some non-pathogenic acid-fast organism. 14. This may also be an explanation for some of the "no lesion" reactors to the double intradermal tuberculin test.