Infection with Mycobacterium kansasii and efficacy of vaccination against tuberculosis.

The purpose of the present study was to examine further the recent hypothesis that subcutaneous infection with Mycobacterium kansasii resulted in the generation of a cell-mediated hypersensitivity reaction ('Koch' reaction) which could, it was argued, subsequently interfere with the generation of acquired immunity following vaccination of the animal with BCG. The results of the present study were unable to confirm this hypothesis in that they show, firstly, that subcutaneous M. kansasii infection was associated with the development of substantial Arthus-like reactivity which masked the detection of any subsequent delayed response, and that furthermore, attempts to adoptively transfer this form of delayed reaction by means of passive transfer of cells were unsuccessful. Furthermore, the results show that, despite the presence of the M. kansasii infection, BCG-vaccinated animals were fully resistant to subsequent aerosol-delivered challenge with virulent M. tuberculosis.