Diluents for stabilization of tuberculin.

Tuberculin is known to be adsorbed to containers and syringes. In the present paper, the adsorption which takes place in the ampoules has been studied in relation to the diluent for the tuberculin.Adsorption was most evident in dilutions prepared with saline or with phosphate buffer containing dextran. The inclusion in phosphate buffer diluent of small amounts of proteins or synthetic surface-active agents decreased or prevented adsorption. A boric-acid sodium-borate diluent containing gum arabic, previously recommended for the preparation of stabilized tuberculin dilutions, was found to be ineffective.The most suitable diluent for the preparation of stable tuberculin dilutions was a 0.05 per thousand solution of Tween 80 in phosphate-buffered saline; this diluent appeared to prevent adsorption under a variety of experimental conditions.The inclusion of Tween 80 in the diluent had little or no effect on the general storage stability of purified tuberculin.Sensitization experiments in guinea-pigs, rabbits and humans showed that no sensitization against Tween 80 need be feared when a 0.05 per thousand solution of Tween 80 in phosphate buffered saline is used in the preparation of tuberculin dilutions.