Results of tests with serial dilutions of lepromin in separate groups of normal young children with a comparison of two lepromins and the Dharmendra antigen

ABSTRACT

To ascertain whether or not high dilutions of lepromin would be practical for the field testing of normal populations, two series of tests were made with healthy schoolchildren aged 6-9 years. The first series comprised five groups averaging 116 children each, all of Opon poblacion (town), the second one five groups averaging 92 each, all of outlying barrios (rural villages). None had been lepromin tested before or BCG vaccinated, and none was given more than one injection of lepromin. In the first series two lepromins made by different methods (M, by Mabalay, and W, By Wade) were compared with each other and with the Dharmendra antigen, and two dilutions (1/10 and 1/20) of the stock W lepromin were also used. The tests in the second series were with five concentrations of the W lepromin 1/1 (i.e., undiluted), 1/10, 1/20, 1/40 and 1/80. With respect to the late reaction, the two lepromins in Series 1 gave the same results, 75 per cent positives. The M stock, however, elicited fewer early reactions than the W stock, suggesting that boiling may be less effective than autoclaving in freeing the soluble antigenic elements involved in that reaction. In series 2 the full-dose W lepromin gave rise to more positive reactions of both kinds than it had in Series 1, and the dilutions gave increasingly large differences with respect to the late reaction. The Dharmendra antigen proved ineffective in eliciting either type of response in these very young and immature subjects, this result with the late reaction probably due to the extraction of the lipids during manufacture....