The influence of ultraviolet irradiation, L-ascorbic acid and calcium chloride on the induction of interferon in human embryo fibroblasts.

The influence of ultraviolet irradiation, L-ascorbic acid and calcium chloride on the production of human interferon was studied in cultures of human embryo fibroblasts (HAT). Interferon (IFN) was induced with Hertfordshire strain of Newcastle Disease Virus (NDV-H) partially inactivated with UV irradiation (NDV-Huv). The interfering properties of various NDV-Huv doses were studied in HAT tissue cultures. The highest IFN yield (IFN U per 10(6) cells) was obtained by using 100 TCID50 NDV-Huv/cell and incubating the induced cultures for 24 h at 37 degrees C. Irradiation of HAT tissue culture with UV doses of 400 and 700 erg/mm2 did not increase IFN production as expected. However, incubation of HAT tissue culture with nontoxic doses of L-ascorbic acid 10(-3) and 10(-4) M or with nontoxic doses of 1 and 4 mM calcium chloride caused an increased IFN production by over 200%.