Abstract
The present report is part of an investigation concerning the capacity of serum from patients who are acutely ill to destroy hemolytic streptococci of the beta type. Previous reports 1 have demonstrated that the bactericidal property under consideration was demonstrable in the serum derived from patients during the period of active disease due to a variety of infections, but that following recovery from illness the streptococcidal activity was greatly diminished, as measured by the methods which were employed. Furthermore, normal sera have been found to be essentially devoid of streptococcidal activity and have served as controls throughout the observations.
The previous articles have described the technical procedures. In the present study a strain of Streptococcus hemolyticus, which has been found to be uniformly highly sensitive to the killing effect of patients sera, has been used in all of the experiments. The samples of sera were derived from patients who were acutely, and usually severely ill from diseases such as pneumonia, or pyogenic infections due to different kinds of organisms.
Studies have been carried out in an attempt to isolate the active principle in serum which is responsible for the streptococcidal activity. Observations have been made with a protein-fraction and a non-protein constituent. The materials have been used separately and in combination.
The protein-fraction most regularly employed in the tests has been obtained by precipitation of serum at low temperatures with alcohol according to the method described by Felton. 2 Sufficient 95 % alcohol was added to serum to make a final concentration of 20%. The material was kept in the icebox overnight in order to obtain the maximal yield and was then spun down in a cold centrifuge.
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