Reprinted Articles

The initial observations of Mitsuda (1) on the use of his "leprous tubercle emulsion" were of purely immunological character, and they revealed the difference in behavior between cases of the lepromatous ("tuberous") and the benign "maculoneural" types. The evolution of such cases observed by Hayashi (2) after testing demonstrated the prognostic value of the reaction, since only those which were Mitsuda negative progressed and became worse. Neither Mitsuda nor Hayashi claimed this reaction to be anything more than an index of resistance to infection, such as is seen in the benign cases and in healthy persons who do not become sick after years of contact with the disease. Bargehr (3), using a paste of triturated lepromas and applying it to skin scarifications, observed the same positivity in "extinct" and bacillus-free cases, but he laid stress especially on the positive results obtained in persons residing in endemic areas and with more or less prolonged contact with leprosy patients. In contrast with those findings were the negative reactions obtained later by de Langen (4) in individuals newly arrived in the Netherlands Indies from Holland, which is free from leprosy. These investigations of Bargehr and de Langen gave rise to the concept of the "positive reaction due to minimal and repeated previous infections producing immunizing antibodies," a concept extended by later workers to the results of the Mitsuda reaction. The question thus arose of whether positivity to lepromin,