Studies on Sensitization. II. Skin Sensitivity and Serum Precipitin Response Following Injections of Unheated and Heated Serum

Abstract

Fresh, unheated human serum is toxic to the rabbit's skin. If 0.1 cc. of such serum is injected intracutaneously, a marked inflammatory response, boil-like in appearance, measuring from 1 to 2 cm. in diameter, follows with subsidence in about 10 days or longer. When human serum is previously heated for 30 minutes at 56°C, however, it has practically no toxic effect on the rabbit's skin. Intracutaneous injection of 0.1 cc. produces a slight transitory thickening of the skin which usually disappears in 24 hours. The question arose, whether the inflammation accompanying the injection of unheated serum might serve as a stimulus to the skin sensitivity and serum precipitin responses of the rabbit. Accordingly, one group of 8 rabbits was injected with unheated serum and a corresponding group with heated serum. Usually 2 injections were employed, the first one being 1 cc, and the second (10 or 14 days after the first), 0.5 cc. These amounts were given intracutaneously in fractional doses of 0.2 cc. The results as demonstrated in the accompanying table, show but little difference in the skin sensitivity and serum precipitin titers following the injection of these 2 types of serum.