SOME OBSERVATIONS ON THE ALLERGY TO TUBERCULIN OF GUINEA PIGS VACCINATED WITH B.C.G.

Abstract

Experiments indicate that the development of allergy in guinea pigs vaccinated with B.C.G. (0.0025, 0.005 or 0.010 gm.), is relatively slow and varies with individuals. It is possible to measure the degree of skin sensitivity by serial intradermal tests with decreasing doses of tuberculin. Classification as to degree of allergy and study of the development of hypersensitivity can hardly be effected on the basis of strong doses of tuberculin. In fact, early positive reaction is not always a sign of lasting hypersensitivity and many guinea pigs, which respond at the same time to a strong dose of tuberculin, can be differentiated as to degree of hypersensitivity by tests with smaller doses of tuberculin. Most of the subcutaneously vaccinated guinea pigs developed allergy in from five to twenty days. The maximum allergy was reached in from one to two months. In a large number of the more sensitive animals the dose was then reduced to 0.00001 cc. and the reaction was maintained during the third and fourth months and perhaps longer. A few animals were sensitive to 0.000005 cc. in the fourth month.The observation has been verified that in subcutaneously vaccinated guinea pigs there is, as a rule, no correlation between small variations in the size of the dose of B.C.G. and the degree of allergy produced. Nevertheless, of the animals vaccinated intraperitoneally, those inoculated with the larger quantities of bacilli were more highly sensitized. This distinction was made by means of the smaller doses of tuberculin.