Le interferon production by human fibroblasts

Abstract

Human leukocyte ( Le) and fibroblast ( F) interferons differ in antigenic properties, physicochemical characteristics, and activity on cells of heterologous species. Previous work from this laboratory showed that two human foreskin fibroblast strains can produce either F interferon alone or both F and Le interferons, depending on the nature of the inducer. The present study demonstrates that both the cell type and the inducer determine the proportion of Le interferon produced by human fibroblast strains. Of eight strains tested, the human GM-258 strain, which is trisomic for chromosome 21, produced the highest absolute and relative amounts of Le interferon after Newcastle disease virus (NDV) inoculation. However, there was no correlation between Le interferon production and number of copies of chromosome 21 in other cell strains examined. Although both NDV and vesicular stomatitis virus (VSV) induced a substantial proportion of Le interferon in GM-258 cells, little or no Le interferon was induced in the same cells by polyinosinic-polycytidylic acid (poly(I)·poly(C) under five different conditions. In GM-258 cells induced with NDV, it was possible to partially manipulate the relative proportion of F and Le interferons and the time at which they were made by altering the conditions of induction. The percentage of Le interferon was increased by decreasing the multiplicity of infection or irradiating the virus with ultraviolet light. Kinetics of F and Le interferon production after different modes of NDV inoculation paralleled each other closely. F and Le interferon production was inhibited to similar degrees in the presence of the glycosylation inhibitors 2-deoxy- d-glucose and d-glucosamine. The bovine EBTr cell strain was used for the selective assay of Le interferon. These cells were as sensitive to Le interferon as human diploid fibroblasts. In contrast, less than 0.1% of human F interferon activity crossed the species line in EBTr cells. Le and F interferons produced by NDV-induced GM-258 cells were physically separated by affinity chromatography on immobilized anti- Le and anti- F globulins. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the Le interferon component produced in GM-258 cells formed two separate peaks (with molecular weights of approximately 18,000 and 25,000), closely resembling a control Le interferon preparation. In contrast, the F interferon moiety made in GM-258 cells formed a single peak on SDS-PAGE, as did control F interferon (molecular weight approximately 26,000).