In an earlier study of the present series1 the inoculation of BCG bacilli (Antigen A) into the skin of patients suffering from leprosy (Mycobacterium leprae: Antigen B) elicited a lesion histologically characteristic of lepromatous leprosy and not of tuberculosis. This response was defined as an "isopathic phenomenon," i. e., a specifically altered tissue reactivity due to which a given host responded to a living antigen (A) in a manner characteristic of its reaction to the continued presence of another antigen (B) to which it had been exposed prior to its contact with Antigen A.
Owing to the close relationship of M. leprae and M. tuberculosis, the question arose whether the isopathic phenomenon observed in the above study might not be due to the presence of antigens common to the two organisms. Since it is a practice in some endemic areas to immunize residents against oriental
LIBAN E, ZUCKERMAN A, SAGHER F. Specific Tissue Alteration in Leprous SkinVII. Inoculation of Leishmania Tropica into Leprous Patients. AMA Arch Derm. 1955;71(4):441–450. doi:10.1001/archderm.1955.01540280017003
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