Experiments Leading to a Possible Basis for Vaccine Therapy in Acute Rheumatic Fever.

Abstract

The experiments and observations of Swift 1 and Birkhaug 2 showed that there is marked similarity in the hypersensitiveness (allergy) to streptococci in animals made hypersensitive experimentally and in patients having acute rheumatic fever.

With this similarity in mind we have carried on a series of experiments in animals to determine the relation between hypersensitiveness and the concentration of antibodies in the blood.

Rabbits were made hypersensitive to streptococci according to Swift's method by injecting 5 cc. of agar heavily seeded with streptococci into the subcutaneous tissue in one area. In from 12 to 15 days these rabbits were injected subcutaneously with 1/100 of a standard amount of streptococci in each of 10 places on the right side and with 1/1000 of the amount in each of 10 places on the left side. The character, number, and size of these nodules were used as an indicator of the degree of hypersensitiveness of the animals. Some of these hypersensitive animals were injected intravenously with streptococci from 3 to 5 days before the multiple subcutaneous injections were made. The serum of the animals was tested for agglutinins at the time of the multiple subcutaneous injections and 5 days later when the animals were killed and the nodules examined.

The following facts were observed: 1. In the hypersensitive animals gross lesions, often large abscesses, were frequently seen. 2. The humoral immunity as indicated by agglutinins was relatively low. 3. Giving an intravenous injection of streptococci to these hypersensitive animals, in from 3 to 5 days before the multiple subcutaneous injections in the back, prevented the development of subcutaneous nodules. 4. These desensitized animals showed a high humoral immunity as indicated by a high agglutinating titer.