The effect of Tween 80 on intradermal tuberculin reactions.

Since 1958, the tuberculin dilutions used in WHO-assisted tuberculosis programmes have been stabilized with the detergent Tween 80, in order to prevent adsorption of tuberculin to the inner surface of the container. However, the reactions to tuberculin with Tween 80 tend to be somewhat softer than those to ordinary tuberculin, for a given size; and, moreover, the curves for the frequency distribution, by size, of the reactions to tuberculin with Tween 80 tend to have a somewhat different shape from those of the reactions to ordinary tuberculin, intermediate-sized reactions (5-10 mm) being less frequent in a given population when Tween tuberculin is used.Further comparisons of tuberculin with and without Tween 80, especially in high doses, are reported in this paper, and it is concluded that Tween 80 has, in addition to its stabilizing effect in vitro, an effect in vivo that may be described as depressive, reducing the size of small reactions in particular. This in vivo effect appears to have no causal connexion with the specificity of the tuberculin or with the origin of the allergy in the population tested.