ABSTRACT
The authors have made a comparative study of the reactions provoked by intradermal injection of lepromin in healthy persons and dogs which are sensitized with M. leprae (designated vaccination hypersensitivity), and those provoked under the same conditions in patients with tuberculoid leprosy (infection hypersensitivity). It is concluded that the mechanism of development of hypersensitivity appears to be similar in all instances, and that the striking thing connected with intradermal injection of lepromin in them is the early, 48-hour, tuberculin type reaction and the accelerated formation of the tubercle or nodule by the end of the first week. The opinion is held that the early reaction in tuberculosis. The Mitsuda reaction is interpreted as the final or terminal stage of the inflammation of the tuberculin-type hypersensitivity, occurring weeks before. It is held that the early and late reactions are different stages of the same process, and that it is not permissible to give them different significances. It is emphasized that in the immunology of leprosy one should study the phenomena of hypersensitivity independently of the phenomena of resistance or immunity, and that there are many reason for believing that they are different states and that they obey different pathogenic mechanisms.
