Abstract
Emulsions of oil droplets in solutions of certain streptococcal proteins have proven to be a means of transforming precipitative reactions into agglutinative reactions. Type-specific aggregation, by means of antistreptococcal antisera, of oil droplets emulsified in solutions of Lancefield's “M” substance are of particular interest.
The solutions used have been solutions of the proteins extracted from Streptococcus pyogenes (Group A αhemolytic streptococci) at neutrality 1 as well as the acid-soluble type-specific protein (Lancefield's “M”) from Streptococcus pyogenes. 2 , 3 The antisera used were rabbit sera prepared by injecting rabbits with living cultures of Type 1 and Type 6 streptococci, and by injecting rabbits with a solution of the neutral extractable proteins.
The experimental technic employed follows: Preparation of the antigen. 0.5 cc of olive oil was emulsified in 20 cc of distilled water. This emulsification was accomplished by putting the material in the magnetostriction oscillator of Chambers† and Gaines and treating with sound waves. 4 , 5 To this emulsion was added the protein solution. This was prepared by dissolving 25 mg of protein in 5 cc of distilled water and carefully adjusting the pH to 7.4 (brom thymol blue indicator). The protein solution and emulsion were then shaken for 15 minutes in a Kahn-test shaker and allowed to stand overnight in the refrigerator. Examination of such b.n emulsion under the dark field microscope showed many minute droplets of oil homogeneously dispersed in water.
Macroscopic Test. To 0.2 cc of antiserum dilution was added 0.2 cc of a 1:3 dilution of the antigen. After thorough shaking, the tubes were placed in the 56°C bath overnight. In the morning the tubes were centrif uged and read. In reading the test it must be borne in mind that agglutinated oil droplets will be found in a creamy layer at the surface of the liquid.
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