STUDIES ON THE INTRADERMAL REACTIONS OF LEPROSY

Abstract

Reported in the following are the findings of the joint studies of lepromin test carried out on a total of 3, 134 in-patients of the national leprosaria and on the 238 school children in non-leprous areas.
1. Comparison of Mitsuda's antigen and Dharmendra's antigen
Mitsuda's antigen is a preparation obtained by grinding and emulsifying the leproma with physiological saline to have a certain difinite concentration and it contains both leprosy bacilli and tissues. On the other hand, Dharmendra's antigen is prepared from the leproma in a certain special manner as would contain mostly leprosy bacilli.
Investigations were made on the active principles of those 2 antigens which participate in the lepromin test. For this purpose, Mitsuda's antigen was injected intracutaneously into the flexor surface of an forearm and Dharmendra's antigen into the other arm exactly in the same manner each in a dose of 0.1ml on 3, 137 leprosy patients. The sizes of erythema read after 48 hours (early reaction) and 15 days (late reaction) were compared for knowing the correlation between those antigens.
The findings were as follows:
a. Correlation of the 48 hous reading between Mitsuda's antigen and Dharmendra's antigen. Correlation coefficient: r=0.8466 n=3, 137
b. Correlation of the 15th day reading between Mitsuda's antigen and Dharmendra's antigen Correlation coefficient: r=0.8652 n=3, 137
c. Correlation between the reading of Mitsuda 15th day and Dharmendra 48 hours Correlation coefficient: r=0.7396 n=3, 137
d. Correlation between Mitsuda 48 hours and Mitsuda 15th day Correlation coefficient: r=0.7674 n=3, 137
e. Correlation between the reading of Dharmendra 48 hours and Dharmendra 15 th day Correlation coefficient: r=0.8056 n=3, 137
Thus, it appears that the same active principle participates in either case of the early reaction or the late reaction.
The findings of the comparisons based on the sizes of induration were of the same tendency, but as the measurement of erythema yielded better comparison than that of induration, in which errors involved were considerable, the intensity of the skin reactions was expressed in the term of so much mm in the diameter of the erythema rather than that of the induration.
2. Criteria for the reading of the reactions of lepromin test
Randomly selected 3, 137 leprosy patients were found to consist of 2, 321 L type patients and 816 of NM type and this ratio of L type and NM type is considered to represent the ratio of those types of leprosy patients in Japan. (Note : L type is the lepromatous type. N, M type means the N type including tuberculoid which was classified in Cairo Congress.) The criteria for the reading of the reactions of lepromin test was established by the analysis of frequency distribution curves of the sizes of erythema regardless to the type of the disease.
The frequency distribution curve of the erythema of 48 hours reading presented a bimodal curve which is the composition of 2 normal distribution curves. The first elevation of the curve was considered to be non-specific while the second elevation specific.
Through the statistical manipulation of those 2 curves, the following criteria have been attained for the reading of the 48 hours reactions of lepromin test.
a. Mitsuda's antigen
i. With the risk of 2% errors: The arithmetical mean of the two diameters of the size of erythema, when below 6mm, the reaction is negative; 7 to 10mm, doubtful positive; 11mm and over, positive.
ii. With the risk of 4% errors: erythema 9mm and below, negative; 10mm and over, positive, and in this case no reaction is taken as doubtful.
b. Dharmendra's antigen
i. With the risk of 1% errors: erythema 9mm and below, negative; 10 to 12mm, doubtful posstive ; 13mm and over, positive.
ii. With the risk of 2% errors, the erythema below 11mm, negative; 12mm and over, positive, and in this case no reaction is taken as doubtful.