Agglutination and Precipitation Reactions in Rheumatoid Arthritis with Hemolytic Streptococci Groups A to G

It has been shown^1-4 that, in a significant proportion of cases, rheumatoid arthritis sera agglutinate certain strains of hemolytic streptococci and precipitate group-specific fractions of these organisms. Lancefield's demonstration of distinct serological groups within the hemolytic streptococci 5 , 6 , 7 has made possible a more detailed study of the nature and significance of these immunological reactions. Agglutination and precipitation tests were carried out with rheumatoid arthritis and control sera using representative strains of Groups A to G as agglutinogens and group-specific extracts as precipitinogens. Similar studies were recently carried out by McEwen, Chasis and Alexander. 8

Agglutination. Seventy-six rheumatoid arthritis sera were examined for agglutinins against Group A organisms, 60 against group B, 47 against group C, 67 against group D, 15 against group E, 15 against group F, and 14 against group G by the technic previously described. 3 The results were classified as “positive,” “doubtful” or “negative”. In classifying the reactions both the character of the agglutination and the titer were taken into consideration. Sera agglutinating in a titer of 1:160 or higher were considered “positive” only if they gave a strong reaction in lower dilutions. Sera agglutinating in a titer of 1:160, 1:320 or even higher were considered “doubtful” unless the reactions in the lower dilutions were definitely more marked than in the higher dilutions. Sera were classified as “negative” when agglutination occurred in dilutions of less than 1:40.