Characterization of a new, continuous rat fibroblast cell line, RFA-1: a high producer of interferon

A new continuous rat fibroblast cell line (RFA-1) was characterized and its interferon (IFN) production and sensitivity to IFN compared with eight rat cell lines. After 95 passages, and about 380 population doublings, these cells exhibited chromosomal heterogeneity, but 55% still possessed the diploid chromosome number of 42. RFA-1 grown in Dulbecco's modified Eagle's medium-10% calf serum have a doubling time of 17.2 h and a saturation density of 141,487 cells/cm2. The geometric mean IFN production by these cells was 10(3.8) U/ml, and this was at least 10(0.5) U/ml higher than IFN production by the second highest IFN producer. Similarly, RFA-1 cells were at least three times more sensitive to the protective effects of interferon against vesicular stomatitis virus-induced cytopathic effects.