Reaction of Rabbits to Streptococci: Comparative Sensitizing Effect of Intracutaneous and Intravenous Inocula in Minute Doses

Abstract

It has been demonstrated that chronic low-grade infection, or numerous localized foci of inflammation induced in the rabbit by repeated minute inoculations with relatively avirulent (green or indifferent) streptococci, evoke a state of hypersensitivity to the bacteria (1, 2). This hypersensitivity may be demonstrated by hyperreaction to minute doses injected intracutaneously, by an ophthalmic reaction following application of the bacteria to the scarified cornea, and by death in from 24 to 48 hours after intravenous doses tolerated by normal animals (2). Suitable preliminary intravenous inoculations result in another type of response; the characteristic hyperergic reactions are not induced; skin lesions are smaller than in normal animals and quickly assume a hard nodular character without much macroscopic evidence of edema; ophthalmic tests are negative; the responses are those of immune animals (3).It is possible that these differences in response of animals to the two modes of preliminary inoculation might be conditioned by a small antibody content in the animals inoculated intracutaneously compared with a larger amount in those inoculated intravenously. The induction of high degrees of bacterial hyperergy with repeated small inocula of streptococci suggested comparing the effect of similar small doses given intravenously; for from both routes a low antibody production might be expected because of the small amount of antigen introduced. Thus, the question as to whether these differences in the reactive state of the tissues might be the result of suitable doses of antigen, rather than of its site of action, focal or general, seemed open to further 591