November 6, 1946
Dr. William B. Castle
Boston City Hospital
I now have a graduate student (Harvey Itano, M.D.) beginning work on the problem of
the relation between the nature of the hemoglobin in sickle cell anemia and the phenomenon
He has not found any references in the literature to the work that you were telling
me about, which, if I remember correctly, indicated that the dividing line between
sickling and non-sickling came at 50 percent oxygenation of the hemoglobin or 50 percent
combination with carbon monoxide. Could you tell me whether you and your collaborators
have published any of this work, send me reprints if it has been published, and send
me a brief statement about the results if it has not been published.
Last summer Dr. Burch told me that he felt sure that the phenomenon was due to a large
amount of carbon dioxide. I have read his papers, and it seems to me that all of
his results can be explained by assuming that the carbon dioxide treatment removes
We are hoping to get some interesting results by studying other compounds of hemoglobin.
With best regards, I am