Enhancement of IgE-mediated histamine release from human basophils by viruses: role of interferon

At the end of the 24-h incubation period, the leukocytes were sedimented by centrifugation at 1,100 rpm for 8 rain and the supernatant fluids were saved for histamine assay or interferon titration. The cells were then washed once with Tris A and resuspended with an appropriate amount of Tris ACM. Duplicate cell samples in 0.1 ml vol were incubated at 37°C with an equal volume of serial dilutions of ragweed antigen E or anti-human IgE. Ai~r 45 min the tubes were transferred to an icebath and 0.3 ml of cold Tris ACM was added. The cells were centrifuged at 1,700 rpm for 15 min at 4°C and the supernatant fluids were assayed for histamine. Total cellular histamine content, expressed as "completes," was determined by lysis of leukocytes with 3% perchloric acid. The histamine released into the supernatant fluids of the "blanks" which contained cells and Tris ACM did not exceed 10% of the total cellular histamine.