Faculty Bibliography

Interferon production stimulated with Polyinosinate-Polycytidylate [Poly (I). Poly (C)] in cultures of human FS-4 cells was enhanced ('superinduced') by the irradiation of cells with UV at the time of induction. UV showed no additional enhancing action on interferon production in cultures already superinduced by the sequential treatment with cycloheximide and actinomycin D; UV doses above 1,000 erg/mm2 inhibited interferon synthesis. In UV-irradiated cells interferon production remained sensitive to inhibition by high concentrations of actinomycin D for at least 3 hr after exposure to Poly (I). Poly (C). Irradiation of induced cells at 4, 5 or 6 hr after stimulation with Poly (I). Poly (C) prevented the rapid decline (shutoff) of interferon synthesis seen in control cultures. All these results support the conclusion that the action of UV protects the interferon mRNA from inactivation. This effect, and the fact that interferon mRNA synthesis can occur after the irradiation of cells with superinducing doses of UV, form the basis of the enhancement of interferon production by UV.

Interferon derived from the human lymphoblastoid cell line, Namalva, was fractionated by antibody affinity chromatography into two antigenically distinct interferon subspecies. At least 13% of the total Namalva interferon activity possessed the F antigenic determinant found on human interferon derived from fibroblast cultures, while the bulk of the Namalva interferon activity had the Le antigenic determinant characteristic for human leukocyte interferon. The separated Le and F subspecies of Namalva interferon differed in the degree of their heterospecific activities on bovine cells. The Le moiety resembled crude leukocyte interferon in that it was highly active in bovine cells. The F component of Namalva interferon showed a lower degree of activity in bovine cells, thus resembling crude fibroblast interferon. When analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and by isoelectric focusing, crude Namalva interferon qualitatively resembled crude leukocyte interferon

The aim of this work has been to isolate and characterize new diploid cell strains, suitable for large-scale production of human fibroblast interferon. Twenty cell strains were isolated from individual neonatal foreskins obtained with the informed consent of the donors' parents. The techniques employed for the isolation of the cell strains were aimed at obtaining the highest possible yield of normal diploid cells, free of contaminating microorganism and viruses. The bulk of the cell yield has been frozen at a low population doubling level. Each of the isolated cultures was tested for interferon producing characteristics with poly(I)-poly(C) under a number of different conditions including 'superinduction' with metabolic inhibitors. Most of the newly established cell strains produced lower interferon yields than the reference FS-4 cell strain. However, some new cell strains produced similar interferon yields as the FS-4 cells on superinduction. Five cell strains, designated FS-30, FS-35, FS-44, FS-48 and FS-49, identified as the highest interferon producers among the new cells, were selected for further testing. Of these, three cell strains (FS-35, FS-48 AND FS-49) produced similar interferon yields as FS-4 cells after superinduction. Cell strains FS-48 and FS-49 were found to have stable interferon producing characteristics over a wide span of population doubling levels. The interferon produced in these new cell strains had the antigenic and biological characteristics of human fibroblast interferon

Antibody against human fibroblast interferon increased the yields of vesicular stomatitis virus in human cells. The results show that endogenous interferon produced in the course of multicycle vesicular stomatitis virus infection depresses virus yields

Polyadenylylated interferon mRNA, obtained from induced human fibroblasts, was quantitatively assayed by synthesis of biologically active human interferon in Xenopus laevis oocytes. The assay for interferon mRNA was used to distinguish between various hypotheses relating to interferon induction and biosynthesis. The data demonstrate that on induction with poly(I-poly(C) human fibroblasts accumulate interferon mRNA for 1-1.5 hr, after which time the mRNA is rapidly degraded with a half-life (t 1/2) of 18 min. Treatment of cells with cycloheximide prolongs the period of accumulation to 3 hr and decreases the rate of mRNA inactivation (t 1/2 = 49 min). Treatment with actinomycin D decreases the rate of inactivation still further (t 1/2 = 68 min). A comparison of cellular interferon synthesis with the relative amounts of interferon m RNA after simple induction or inductionin the presence of the inhibitors (superinduction) indicated a general correlation. Thus, on induction, the genes for interferon are activated to produce a transcript for a short time. The superinducing treatments prolong the period of accumulation and decrease the rate of degradation of this transcript

Human fibroblasts and leukocytes produce interferons which may be distinguished by their antigenic and species specificity as well as by their molecular weight distributions. To elucidate the basis for these differences, we isolated mRNA from induced human fibroblasts and lymphoblastoid (Namalva) cells and studied the products of translation in Xenopus laevis oocytes. The mRNA from the respective cells yielded translation products, in oocytes, that were characteristic of the cells from which the mRNA was derived. We conclude that human cells contain at least two structural genes for interferon, coding for polypeptides differing in primary sequence. Fibroblasts synthesize a single species of interferon; lymphoblastoid cells synthesize two species, the fibroblast and leukocyte types

The inhibitors of glycosylation, 2-deoxy-D-glucose or D-glucosamine, inhibit the synthesis of biologically active interferon in human FS-4 fibroblast cultures stimulated with polyinosinate-polycytidylate. Interferon synthesized in the presence of partially inhibitory concentrations of 2-deoxy-D-glucose or D-glucosamine were found to differ from interferons made in control cultures in some physical properties. Interferons synthesized in the presence of either inhibitor had a diminished charge heterogeneity demonstrable by iso-electric focusing. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, control interferon activity formed a single peak with the apparent molecular weight of 20,000, whereas interferons from cultures treated with either inhibitor could be resolved into two distinct molecular weight components, one of which was smaller than the interferon synthesized in control cultures

Biologically active human interferon was synthesized de novo in a cell-free mouse extract stimulated with messenger RNA from induced human fibroblasts. The identity of the antiviral activity as human interferon was demonstrated by its antigenic and species specificity. Some characteristics of the cell-free synthesis were described