Abstract
It is generally believed that while it is possible to desensitize rabbits injected with a purified protein such as crystalline egg albumin, it is not possible to desensitize these animals when injected with a complex mixture of proteins such as serum or egg white. On reinvestigating this problem, it was found that rabbits can be readily desensitized to serum and egg white, the desensitization, however, being of short duration. In the early experiments, large quantities, such as 10 or 20 cc. of these proteins were injected intravenously to produce desensitization. Later experiments indicated that relatively small amounts, such as 1 cc. or 0.5 cc. per kg. of body weight of rabbits, were sufficient to desensitize.
Table I illustrates desensitization in 2 rabbits, sensitized to human serum that had previously been heated for 30 min. at 56° C. Rabbit 173 had a skin sensitivity titer of 1,000, but no serum precipitins. By injecting intravenously 0.5 cc. of human serum per kg. of body weight, the skin sensitivity tests given 1 hour and 6 hours later, were practically negative, the skin response being limited to the injections of undiluted serum—a response commonly given by normal rabbits. Forty-eight hours after the desensitizing injection, the skin response was 100; in 120 hours, it reached the original level. Of interest is the fact that the precipitin titer which was negative at the time of the desensitizing injection, reached 10,000 120 hours after this injection.
Rabbit 213 which showed a skin sensitivity titer of 1,000 and a serum precipitin titer of 10,000, was completely desensitized after an intravenous administration of 0.5 cc. human serum per kg. of body weight. One noted a return to the sensitized state 48 hours after the desensitizing injection.
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