VII. Active principles of tuberculin prepared from non-protein substrates.

Abstract

Conclusions

It has been shown for the first time that small amounts of tuberculin fractions prepared from protein-free synthetic substrates are capable of sensitizing normal, non-tuberculous guinea pigs. In these animals, typical skin reactions can he elicited subsequently by intracutaneous injection of minute amounts of homologous as well as heterologous fractions and of unfractionated tuberculin form which such fractions have been prepared.

Clinical trial of these fractions in juvenile patients has demonstrated for the first time that the substances have diagnostic value. Positive skin tests were perfectly correlated with positive clinical and laboratory findings of tuberculous infection. Such was not the case for ordinary old tuberculin in over 20 per cent of young patients in a group of 150 who were studied routinely. In a number of instances the observations suggested that the reactions might be correlated with the degree of activity or with arrested tuberculous infection.

The present studies point to a method which makes an accurately standardized tuberculin available for routine clinical work. It is believed that the active principle of tuberculin can best be isolated by this or by a similar method.

The observations on sensitization suggest that these may be applied to studies of immunity, and by extension, to therapeutic studies in the experimental animal. Such work, now in its third year of progress, will be reported in the future.