Grove and Coca1 called attention to the fact that ragweed pollen extracts may be freed from their protein content and yet remain active, as determined by skin tests on sensitive persons. One of us2 has reported similar results and shown that, after the removal of all protein, the pollen extract remains quantitatively active, as determined by the instillation of the extract into the nostrils of a sensitive person. It was also shown that the component which acts as the antigen when pollen extracts are used in complement fixation tests is removed by protein digestion and, while the extract is no longer antigenically active, its symptom producing power is undiminished. Evidence was presented that the nitrogen content of extracts does not parallel the activity of the pollen intranasally.
Additional verification of the latter statement may be found in the following: A well known biologic house made extracts of ragweed
BLACK JH, MOORE MC. POLLEN THERAPY WITH PROTEIN-FREE EXTRACTS. JAMA. 1926;86(5):324–325. doi:10.1001/jama.1926.02670310006002
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