A modification of the lepromin test.

Lepromin is an antigen prepared by grinding 1 'gm. of autocJaved bacteriologically positive tissue in 20 ml. of normal saline, a concen­ tration of 1 :20. The test is made by injecting 0.1 ml. i ntradermally . At the end of 24 to 48 hours, there is a tuberculin like response which rapidly fades, to be succeeded in most instances by a nodular infiltra­ tion which reaches its maximum size in three to four weeks. The early reaction is allergic, less constant, and may include a non-specific element due to tissue debri s ; the late result, the Mitsuda reaction, is thought to depend on the presence of whole bacilli and to indicate resistance to infection, because those with a negative Mitsuda develop the more serious forms of leprosy, and those with a strongly positive reaction, the milder forms. The late reaction is measured as follows :Infiltrations of 1 and 2 mm. are designated ± doubtful Infiltrations of 3 and 4 mm. are designated + weakly positive Infiltrations of 5 rom. and over are designated + + positive Ulceration is designated + + + strongly positive.