Hemagglutination Reaction in Streptococcal Infections and Acute Rheumatic Fever. ∗

Abstract

Summary and Conclusions

(1) The hemagglutination technic of Middlebrook and Dubos has been applied to the study of streptococcal infections and rheumatic fever. Two of 4 streptococcal extracts gave excellent sensitization of sheep erythrocytes. These were the formamide extract, containing the group specific carbohydrate, and a concentrated solution of streptolysin O, which is a protein. Surprisingly, hemagglutination titers were identical with a variety of human sera when these two preparations were used as sensitizing antigens. (2) Hemagglutination was shown by many sera in titers ranging from 1:4 to 1:128, but there was no correlation between the magnitude of antistreptolysin and hemagglutination titers. Patients with non-strepto-coccal respiratory infections, streptococcal pharyngitis, and acute rheumatic fever could not be differentiated on the basis of the hemagglutination test. (3) The one consistent observation was that, for any one patient, hemagglutination titers tended to remain constant with both acute and convalescent sera. This suggests that a cross reaction of some type was responsible for the agglutination of red cells sensitized with streptococcal products. Further study is necessary to clarify the nature of this phenomenon.