Quantitative Studies of the Tuberculin Reaction: I. Titration of Tuberculin Sensitivity and Its Relation to Tuberculous Infection

Abstract

In the quantitative method used, a number of doses of tuberculin PPD of different conc. were employed so as to determine for each person tested the approx. dose (in nag.) to which he reacted. Each dose was 10 times more concentrated than the preceding one, ranging from 1/100 billionth of mg. to 1 mg. The same PPD tuberculin soln. and testing technique were used throughout. Among 553 orphanage children aged 6-19 yrs., 20% reacted to dose equivalent to first strength PPD, 50% to dose equivalent to 2d PPD, and all but 4% to 1 mg. or less. 77% of children with history of contact with tuberculosis reacted to dose equivalent to first strength PPD but only 6.5% of those without contact history. Tests on other contact groups revealed that 70-90% react to dose equivalent to first-strength PPD. Tests on over 500 cases of tuberculosis revealed that 90% reacted to this dose of PPD and over 99% to a dose 5 times as strong or 1/10,000 mg. Non-contact infants did not react to first-strength PPD but to 1 mg. over 70% of those under 6 months, and 95% over 6 months, reacted.