Abstract
For a number of years it has been known that some pneumococcic strains possess the Forssman antigen and hence produce in the blood of immunized rabbits hemolysins for sheep blood and agglutinins for blood of Group A. According to a recent report 1 this antigen is present in all strains of pneumococci except those of Types IV, VIB, XI, and XXXI. Prominence was given to these facts only recently on account of the current increased use of therapeutic sera derived from rabbits.
We were led to examine the hemagglutinins and hemolysins of all antipneumococcic therapeutic sera available (rabbit and horse), especially in view of recent reports which indicate that horse sera containing strong-titered agglutinins for human blood were responsible for occasional fatal acute hemolytic reactions. 2 , 3 , cf. 4 These accidents were due to injection of horse serum Type XIV.
Our own experiments are based on tests done with therapeutic sera administered to patients at the Harlem Hospital. The sera were tested in dilution of 1:50 for hemolysins of sheep blood and for agglutination of human blood of Groups O, A2. A1, and B. Hemolysins for sheep blood were tested by adding 1 drop of 50% suspension of washed sheep-cells to a mixture of 0.5 cc of serum-dilution and 0.5 cc guinea-pig complement 1:10. Tests for agglutination were made by mixing in small tubes 2 drops of a 2% washed blood suspension and 2 or 3 drops of serum dilution; readings were made after the tests stood for one hour at room temperature.
Our results indicate that antipneumococcic rabbit sera of numerous types contain hemolysins for sheep blood and agglutinins with specific action on human blood of Group A.
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