Studies on the Lepromin Test

When leprolin antigen is injected repeatedly into BCG sensitized guinea pigs, the leprolin reaction relatively easily becomes negative although the tuberculin reaction is not affected. When viable peritoneal cells of the tuberculin positive-leprolin negative guinea pig, sensitized with BCG, are transplanted to the normal guinea pig, the recipient showed negative leprolin and positive tuberculin reactions.Furthermore, both tuberculin and leprolin reactions in the BCG sensitized guinea pig, repeatedly desensitized with tuberculin antigen, gradually subsided, and positive tuberculin and leprolin reaction was not induced in the recipient guinea pig by the passive peritoneal cell transfer from the guinea pig which had been desensitized with tuberculin.The above mentioned and previously reported finding that the inactivation of common reacting factors, corresponding to tuberculin and leprolin antigens, occurs as a result of the combination of the peritoneal cells of guinea pig, either sensitized and non-sensitized with BCG, with leprolin antigen in vitro. These experimental findings may offer a clue for the difficulty in sensitizing the guinea pig with human leprosy bacilli.