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

Virus Preparation. Herpes simplex virus type 1 (HSV-1), adenovirus type 1 (Adeno-1), and simian foamy virus type 7 (SFV-7) were propagated and assayed in PRK cells. Influenza virus type A (PR-8) and parainfluensa virus type 1 (Sendal) were propagated and assayed by inoculation of the allantoic fluid of embryonating hen's eggs. Virus pools, uninfected PRK cell controls, and allantoic fluids were centrifuged at 2,000 rpm for 10 rain to remove cell debris. The supernatant fluids were centrifuged at 30,000 rpm for 2 h and the pellets were resuspended in Dulbecco's phosphate-buffered saline (PBS) to 1/10 the original volume. Single virus pools containing the following titers were used throughout the study: HSV-1, 1.3 × 10 s plaque-forming units (PFU)/ml; Adeno-1, 5.6 × 107 tissue culture infectious dosesso (TCIDso)/ml; SFV-7, 1 x 10 e TCID~/ml; Influenza A, 3 × 109 egg infectious dosesso (EIDso)/ml; and Sendai, 3 × 10 ~9 EID~o/ml. Leukocyte Preparation. Human peripheral blood was mixed with 2.25 ml of Dextran (Dextran 6% wt/vol in saline, Abbott Laboratories, North Chicago, Ill.) supplemented with 0.25 ml of 15% glucose and 1.0 ml of 0.1 M EDTA per 10 ml of blood. The mixture was allowed to settle at room temperature for about 90 rain. The leukocyte-rich plasma was removed and the cells were sedimented at 1,200 rpm for 8 rain at 4°C and suspended in Tris A-EDTA. Removal of red blood cells was accomplished by a 30-s hypotonic shock. After sequential washes in Tris A-EDTA and RPMI medium, the leukocytes were resuspended in RPMI medium containing 2% FBS (21) .