Blood from forty-one persons with atopic disease was incubated with various concentrations of specific antigen. The amount of histamine released into the plasma was measured chemically. Histamine was released by concentrations of pollen extract as low as 0.01 meg. protein nitrogen per liter of blood; more histamine was released by greater amounts of antigen until a maximum level was reached at antigen concentrations of from 4 to 20 meg. P.N. per liter of blood. Histamine release tended to be suppressed by high concentrations of antigen unless massive amounts were used (4,000 meg. P.N. per liter of blood), at which point nonspecific release occurred. The degree of skin reactivity of the subjects studied was related inversely to the antigen concentration producing maximal histamine release. The rate of histamine release was apparently linear, maximum release being approached only after at least thirty minutes of incubation of blood with the specific antigen.
Bibliographical noteFunding Information:
Blood Donors,-These were persons with clinical evidence of atopic disease whose sensitivity was confirmed by intracutaneous tests. All of them were in good health, many being medical students or laboratory personnel. With a few exceptions, the blood was obtained at a time when the person was asymptomatic. None of these persons had received previously any antigen injections for the purpose of desensitization. s A majority of persons were strongly sensitive either to ragweed or to timothy pollen. The remainder were sensitive to tree or English plantain pollens or were laboratory personnel who had developed allergic symptoms on exposure to experimental animals. From the Department of Medicine University of Washington School of Medicine. Seattle, Washington (Dr. VanArsdel) and the Department of Medicine, Columbia university of Physicians and Surgeons, New York City (Drs. Middleton, Sherman, and Buchwald). Aided by a grant from the Initiative 171 Fund of the State of Washington and a grant from the National institute of Allergy and Infectious Diseases. Received for publication June 9, 1958, ‘Work done during a Student Summer Research Fellowship granted by the National Foundation for Allergic Diseases, 1956.