Abstract
It has been established 1 , 2 , 3 that hemolytic streptococci are agglutinated by sera of patients with rheumatoid arthritis. It has also been shown 4 , 5 that the C substance of hemolytic streptococci 6 gives precipitation with sera of patients with this and other diseases. Since only strains of hemolytic streptococci isolated from human sources had been used in the investigations quoted, the present study was undertaken to observe the results obtained when antigens for agglutination and precipitation were prepared from hemolytic streptococci of Lancefield's groups A, B, C, D, E, F, and G. 7 Strains of groups B through G were kindly provided by Dr. R. C. Lancefield.
Agglutination tests were done with strains of groups A through E only. Eighteen-hour living broth cultures in 0.5 cc. quantities were mixed with 0.5 cc. of the various dilutions of serum obtained from patients with rheumatoid arthritis. Tests were read after 2 hours at 56°C. and 20 hours in the ice box. The results (Table I) indicate that, while the strongest agglutination usually occurred with strains of Group A, definite reactions were obtained also with those of other groups.
It seemed probable that the cross reactions were due to non-group-specific fractions common to all the strains, and to test this the work was repeated using the precipitin reaction against the group-specific C substance. Crude C extracts of strains of groups A through G were prepared by Lancefield's method. 7 These were tested against sera of 11 rabbits immunized with representative strains of each group. In each instance antigen dilutions were prepared by adding 0.4, 0.1, 0.025, and 0.01 cc. of extract to sufficient physiologic saline to make a final amount of 0.4 cc. Following the addition of 0.2 cc. of serum, the tubes were kept 2 hours at 37°C. and 20 hours in the ice box, and were then read before and after centrifugation.
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