A simple chemical procedure has been outlined for the isolation of a fraction from H. pertussis which has the following properties:

  1. It is antigenic; when injected into rabbits intravenously, it gives rise to agglutinins against H. pertussis in phase I.

  2. It absorbs quantitatively agglutinins from H. pertussis antiserum.

  3. It is non-toxic, as demonstrated by tests on rabbits and human beings.

  4. It has been used successfully as a material for skin-tests for susceptibility to whooping-cough.

  5. The agglutinogen may well serve as a means of reinforcing waning active immunity to pertussis.

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This work was aided by a grant from the United States Public Health Service.

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