ABSTRACT
Comparative tests of Wade's "purified acillus suspension" and the standard lepromin prepared from the same pool of leproma have been made in the Philippiones, Netherlands New Guinea, East Africa and South Africa. Consistently in the comparisons the standard lepromin gave more positive Mitsuda reactions, or more strong reactions, than the suspension; and in the healthy children tested the PBS sometimes gave negative results when the reactions to lepromin were positive. For this reason alone it would not be satisfactory for use in field work in which children are involved. Lepromin gave more early reactions than the suspension in the cases for which that effect was reported (Philippines), suggesting that in the preparation of the latter the immediately-available antigenic elements had partly been eliminated. The suspension on the whole caused somewhat less ulceration of the reaction lesions, which is a point in its favor. However, contrary findings were not infrequent, so use of the product could not be advocated strongly on that ground. The results in tuberculoid cases permit comparison of the reactivities of the four different regional groups, whether considering average sizes of the reaction lesions or the percentage of the stronger reactions. Despite the high percentages of positive reactors in the Philippine subjects, the New Guinea people proved to be distinctly more so, and the East African cases the most reactive of all. The South African cases were much less reactive in comparison. The question of why people living in different environments differ materially in reactivity remains an intriguing problem.