Experimental study on the relapse of tuberculosis after the termination of antituberculous chemotherapy using immunodeficient nude mice.

The effect of cellular immunity induced by tuberculous infection on bacteriological relapse after the termination of antituberculous chemotherapy was studied experimentally using immunodeficient nu/nu mice and immunocompetent dd mice. The efficacy of intensive chemotherapy was excellent even in nu/nu mice; tubercle bacilli in the organs decreased below the detectable limit, but formidable regrowth of bacilli was seen after the termination of chemotherapy. On the other hand, in the case of dd mice that established antituberculous cellular immunity through tuberculous infection, bacteriological relapse was generally very slight. It was concluded that bacteriological relapse was related closely with the established cellular immunity induced by the infected tubercle bacilli.