May 28, 1943

Dr. Frank Blair Hanson

The Rockefeller Foundation

49 West 49^th Street

New York, New York

Dear Dr. Hanson:

I thank you for your letter of May 24, which answers the questions which had teen troubling me.

Professor Sturtevant has told me that his answer to your earlier letter was mailed today.

I think that the opinion which I expressed in my letter of May 17 regarding the importance of artificial antibodies in comparison with the other investigations in the field of immunochemistry which we are making did not tell the whole story. From the point of view of pure science, the other investigations are, I think, of greater interest and importance than the manufacture of artificial antibodies, because they lend themselves to more definite and straightforward theoretical interpretation. On the other hand, the manufacture of artificial antibodies offers some promise of being of practical value in, the prevention and control of disease, and when I think of this I become enthusiastic about artificial antibodies, and am tempted to rank this part of our work as the most important. As mentioned before, our experiments with artificial antibodies against Type I pneumonia indicate a small but definite protective power; I am disappointed that striking protection has not been achieved.

I thank you for recommending that the sum of $8,000.00 be provided for continuing our work on the production of artificial antibodies during the coming year. I am confident that during the coming months we shall obtain enough information to give a reasonably definite answer to the question of whether or not artificial antibodies will be of practical aid in the protection against and treatment of disease.

Sincerely yours,

Linus Pauling