The lepromin reaction was described at first by Mitsuda in 1919. He discovered that boiled ,emulsion of lepromatous tissue rich in lepra bacilli induces a nodular reaction a few weeks .after intracutaneous injection.
The role of lepromin test is-different from those of the tuberculin reaction. The lepromin
shows strong positive result not only in healthy contact persons. According to the recent
studies, a specific antigen produced by acid-fast bacilli from soil and other sources.
A positive correlation between lepromin and tuberculin sensitivities has been described by
several writers.
The early (Fernandez) reaction is a response to a sensitivity already established in the patient, either by previous experience with M. leprae or through cross-sensitivity resultting from contact with other Mycobacterium, eg. M. tuberculosis. The late(Mitsuda) reaction is a ,evidence of resistance or immunity to M. leprae resulting from antigen-antibody reaction.
Reading of reaction:
1. Erythema and induration developing 24-48 hours after injection, remaining for 3-5 days. (Fernandez early reaction)
2. Late reaction develops 3-4 weeks after the injection, often termed the Mitsuda reaction. Kinds of Lepromin antigen:
1. Integral lepromin (L. I. )
2. Bacilillary lepromin (L. B. )
.3. Purified lepromin protein(L. P. P. )
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