This paper confirms and extends our previous studies of skin-test responsiveness and suppression in Nepal. The ability of leprosy patients to make positive responses to group i and group ii (common mycobacterial, and slow grower associated) antigens is markedly impaired in comparison with healthy school children. Of the 2 suppressor mechanisms associated with mixtures of reagents prepared from fa st and slow growers which were demonstrated in Bombay, only the phenomenon of local suppression

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... iously seen in Nepal was fo und. Although originally thought to be associated with group iv (species specific) antigens of fast growers, the phenomenon occurred whichever reagent of 9 fa st growing species was mixed with the slow grower reagent. Thus our present view is that the phenomenon demonstrable in both Bombay and Nepal is related to the presence of antigen common to any fa st growing species. The observation of this suppressor mechanism in leprosy patients, leprosarium staff and healthy school children shows that it is unlikely to be related to the disease, although it may be related to susceptibility to it. Our inability to demonstrate in Nepal the distant suppressor mechanism fo und in Bombay suggests that this may be due to geographical differences, probably in the amount of oral contact with environmental mycobacteria, and perhaps in the species that are present. A system of quadruple skin-testing employing 3 mixtures of new tuberculinsl and Burulin,2 prepared fr om My cobacterium ulcerans, was designed for the investiga- § Address for reprints: