Sensitivity to Horse Serum Due to Previous Injections of Antigen

Abstract

There have been conflicting reports concerning the reactions which follow the injection of serum into subjects who have previously received prophylactic or therapeutic doses of the same agent. Hooker and others 1 expressed the belief that the small amount of horse serum contained in diphtheria toxin-antitoxin was enough to sensitize some subjects to that antigen. Although others 2 have not denied this possibility, they have expressed the opinion that such small amounts of horse serum as are contained in toxin-antitoxin mixtures are of no practical importance in inducing sensitization.The purpose of this investigation was to ascertain by cutaneous and ophthalmic tests (1) whether persons previously given toxin-antitoxin or serum had become sensitized to horse serum, (2) whether more positive reactions to tests for sensitivity to horse serum are obtained from persons previously given serum than from those not so treated and (3) whether there is any relation between the results of intradermal and ophthalmic tests for sensitivity and the occurrence of serum sickness. The last question was investigated despite the fact that the