1963 Volume 32 Issue 3 Pages 129-132
The reliability of bacillary counting for the standardization of lepromin was examined using the undiluted standard lepromin and its 1:2, 1:4, and 1:8 dilutions. A linear relationship was demonstrated between the dilution degree and numbers of leprosy bacilli contained there. Size of the skin reactions was read in leprosy patients comparing between those elicited by the undiluted standard and by diluted antigens. The result indicated that the reaction size becomes smaller with the dilution degree of the antigen. Therefore, a parallelism between the potency of lepromin and the number of bacilli in the antigen was made clear. It is possible to settle the criterion of lepromin potency in the term of bacillary number. It was found that when lepromin is prepared by the same procedure using a pool of many leprous nodules, it contains leprosy bacilli in number from 150 million to 160 million per ml.
