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Biomedical subjects

J Vilcek

Publications and source records attributed to J Vilcek.

At least 163 records · Page 9Linked to original sources
PubMed1981

Partial purification and characterization of human gamma (immune) interferon.

Human gamma (immune) interferon (IFN-gamma) was produced in lymphocyte cultures stimulated with a phorbol ester (12-O-tetradecanoylphorbol 13-acetate) and purified phytohemagglutinin. Physicochemical analysis showed that human IFN-gamma is a glycoprotein with an isoelectric point around 8.6 and an apparent molecular weight of 58,000 +/- 3000. A purification process for IFN-gamma was developed consisting of sequential chromatographic separations on controlled-pore glass, concanavalin A-Sepharose, and Bio-Gel P-200. This purification process resulted in an increase in specific activity from about 10(4) (crude culture fluid) to an estimated 10(7) units per mg of protein with a cumulative recovery of about 40% of the IFN activity.

Chromatography, Affinity↗
PubMed1981

Partial characterization of gamma (immune) interferon mRNA extracted from human lymphocytes.

gamma (immune) interferon (IFN-gamma) was induced in cultures of fresh human lymphocytes by combined treatment with a phorbol ester (12-O-tetradecanoylphorbol 13-acetate, TPA) and the T cell mitogen phytohemagglutinin (PHA). Compared to the IFN-gamma yields obtained with PHA induction alone, the inclusion of TPA caused a significant enhancement of IFN-gamma production. Poly(A)-containing mRNA was isolated from mononuclear cells induced with TPA and PHA. Injected into Xenopus laevis oocytes, this mRNA preparation gave rise to IFN activity with characteristic properties of human IFN-gamma. Sucrose density gradient centrifugation analysis showed that IFN-gamma mRNA sedimented at 15 S, suggesting that it contains a total of about 1400 nucleotides.

Animals↗
PubMed1981

Entrapment of human leukocyte interferon in the aqueous interstices of liposomes.

Human leukocyte interferon has been trapped in the aqueous interstices of multilamellar liposomes (phosphatidylcholine, dicetyl phosphate, and cholesterol [7:2:1]). Such liposomes trapped [3H]inulin (aqueous space marker) and interferon to the extent of 0.22 +/- 0.01 mg (n = 8) and 350 +/- 54 U (n = 4) per mumol of liquid, respectively, as judged by molecular sieve chromatography. Interferon trapped within liposomes was resistant to tryptic digestion under conditions which completely inactivated free interferon. Studies in which interferon was added to preformed liposomes excluded the possibility that interferon bound nonspecifically to the outer layer of the multilamellar liposomes. When interferon was added to the aqueous medium in which liposomes of various net surface charges were permitted to form, trapping of interferon varied directly with the interlamellar aqueous compartments of the liposomes. The demonstration that stable liposomes can entrap interferon suggests that these may constitute suitable vectors for the delivery of interferon to cells.

Humans↗
PubMed1981

Stimulation of human gamma interferon production by diterpene esters.

The diterpene ester 12-O-tetradecanoylphorbol-13-acetate (TPA) and several structurally related compounds were tested for their ability to stimulate interferon (IFN) production in primary cultures of human leukocytes. In cultures of Ficoll-Hypaque-purified mononuclear cells, TPA treatment alone induced only low levels of IFN, but TPA pretreatment of cells caused significant enhancement of IFN yields produced with phytohemagglutinin or several other T cell mitogens. In cultures of unprocessed cells derived from plateletpheresis residues or buffy coats, TPA treatment alone induced high levels of IFN and costimulation with TPA and phytohemagglutinin produced some further enhancement of IFN production. Phorbol 12,13-dibutyrate was comparable to TPA in its ability to enhance phytohemagglutinin-induced IFN production. Several other phorbol ester analogs were also active, but maximal stimulation occurred only at higher drug concentrations. Mezerein, a structurally related diterpene ester, was at least as active as TPA in stimulating IFN production in either Ficoll-Hypaque-purified or unprocessed cells. IFN produced after stimulation with TPA or mezerein, singly or in combination with phytohemagglutinin, had several properties characteristic of IFN-gamma, e.g., it was largely inactivated by dialysis at pH 2, or after exposure to sodium dodecyl sulfate, whereas it was not neutralized by antibody to IFN-alpha and IFN-beta. The stimulatory effect of diterpene esters has proved helpful in producing IFN-gamma for physicochemical analysis and other studies.

Cell Separation↗
PubMed1981

Inhibitory effects of human leukocyte and fibroblast interferons on normal and chronic myelogenous leukemic granulocytic progenitor cells.

Inhibitory effects of two human interferon preparations, leukocyte interferon (Le-IF) and fibroblast interferon (F-IF), on granulocytic progenitor cells (CFU-C) from hematologically normal cancer patients and from patients with chronic myelogenous leukemia were evaluated. There was a wide variation in sensitivity of CFU-C to both Le-IF and F-IF. F-IF was mor inhibitory against CFU-C than le-If. Normal CFU-C and chronic myelogenous leukemia CFU-C were equally inhibited by both interferons. Effects of both interferons were neutralized by corresponding specific antisera but not by the other antisera. These observations confirmed that differences in immunogenicity of the interferons may attend their different origins.

Cells, Cultured↗
PubMed1980

Le interferon mRNA from human fibroblasts.

Human F and Le interferon can be clearly distinguished on the basis of different antigenic properties and host range. After inoculation with Newcastle disease virus (NDV), GM-258 fibroblasts produced Le as well as F interferon; in contrast, only F interferon was detectable after stimulation with poly(I) . poly(C). Polyadenylylated mRNA isolated from fibroblasts induced with poly(I) . poly(C) or NDV was injected into Xenopus laevis oocytes and the interferon activities thus produced were analyzed. Only F interferon production was demonstrable in oocytes injected with mRNA from cells induced with poly(I) . poly(C), whereas both F and Le interferons were made in oocytes injected with mRNA from NDV-induced cultures. The time course of accumulation of F and Le interferon mRNAs in NDV-induced cells corresponded to the kinetics of F and Le interferon synthesis in intact cells. The ratio of F and Le interferons made in oocytes was similar to that observed in intact GM-258 cells. F and Le interferon mRNA activities isolated from GM-258 cells could not be separated by sucrose density gradient centrifugation. However, the profile of F mRNA activity was more heterogeneous and its peak sedimented somewhat more slowly than that of Le interferon mRNA. These results suggest that the varying ratios of F and Le interferon synthesis in different cells after different modes of stimulation are determined at the level of mRNA. The induction mechanisms of F and Le interferon mRNA synthesis appear to be closely related but not identical.

Animals↗
PubMed1980

Attempts to induce interferon production by IdUrd induction and EBV superinfection in human lymphoma lines and their hybrids.

Inducers of the Epstein-Barr virus (EBV) cycle, 5-iodo-2-deoxyuridine (IdUrd), phorbol myristate acetate (TPA) and sodium butyrate were tested for their ability to induce EBV-determined antigens, early antigen (EA) and virus capsid antigen (VCA), and to stimulate interferon (IF) production in a variety of EBV-carrying lymphoid cell lines. IdUrd and TPA induced IF production to various extents in the different lines, whereas sodium butyrate did not. There was no relationship between induction of the EBV cycle and production of IF; the two appear to be independent characteristics. Superinfection with the transforming B95-8 virus substrain of EBV induced IF production, whereas superinfection with the abortively cytopathic, non-transforming P3HR-1 substrain had little or no IF-inducing effect, in spite of its highly potent effect on virus antigen (particularly EA) synthesis. Analysis with specific antisera against IF showed that IF preparations produced by three different lymphoid cell lines in response to IdUrd treatment were composed of a mixture of the Le and F antigenic types, with the latter forming a minor species. In contrast, no detectable F interferon was present in spontaneously produced IF preparations from Namalwa cells, or after induction with B95-8 virus.

Antigens↗
PubMed1980

Pharmacokinetic properties of human fibroblast and leukocyte interferon in rabbits.

When rabbits were given intramuscular injections of the same quantities of human leukocyte or fibroblast interferons, the former produced moderately higher levels of circulating interferon. Fibroblast interferon was not cleared faster from circulation, nor was direct inactivation by rabbit blood responsible for this difference.

Animals↗
PubMed1979

Interferon induction with Newcastle disease virus in FS-4 cells: effect of 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB).

DRB is an inhibitor of heterogeneous nuclear RNA (hnRNA) and messenger RNA (MRNA) synthesis. The effect of DRB on interferon production stimulated by Newcastle disease virus (NDV) in the human FS-4 cells was studied. Interferon production in cells primed by treatment with interferon was markedly enhanced (superinduced) in the presence of DRB. This superinduction was essentially due to an inhibition of the rapid decline (shutoff) of interferon production observed in primed cells not treated with DRB. Continuous presence of DRB was required for maximal superinduction. In this and other respects the interferon response induced by NDV in primed cells resembled poly(I). poly(C)-induced interferon production. In contrast interferon production in cells not primed with interferon was virtually abolished by DRB treatment. Since neither virus specific RNA synthesis nor virus replication were significantly affected by DRB, the inhibition of interferon production is likely to result from the inhibitory action of DRB on a cellular, rather than viral, function. Apparently some differences exist in the synthesis or processing of the mRNAs for interferons in primed and unprimed cells and these determine the different sensitivities of these two responses to DRB.

Cell Line↗
PubMed1979

Initial interaction of human fibroblast and leukocyte interferons with FS-4 fibroblasts.

Human FS-4 cells were exposed to human fibroblast interferon for various times and further incubated in the absence of interferon until challenged with vesicular stomatitis virus. Addition of antibody to fibroblast interferon at the time of removal of interferon did not alter the development of the antiviral state. If cells were exposed to interferon for 45 min at either 0 or 37 degrees C, they developed resistance upon subsequent incubation at 37 degrees C. However, less resistance developed if the cells were initially incubated at 0 degrees C. Our results indicate that a single interaction of fibroblast interferon with susceptible cells, either at 0 or 37 degrees C, is sufficient for the subsequent development of an antiviral state, at least in the short term experiment. The kinetics of development of the antiviral state were compared with fibroblast and leukocyte interferon. The rise in the degree of antiviral resistance was steeper and maximal levels of resistance were reached sooner when FS-4 cells were incubated with increasing concentrations of fibroblast interferon than with leukocyte interferon. This suggests a greater affinity of fibroblast interferon for these cells.

Antibodies↗
PubMed1979

Interferon induction with Newcastle disease virus in FS-4 cells: effect of priming with interferon and of virus inactivating treatments.

Inoculation of human FS-4 cells with Newcastle disease virus (NDV) resulted in the induction of two distinct interferon responses, one that peaked at about 5 hr (early response) and one that reached a maximum between 10 to 24 hr after inoculation (second response). The early interferon response was enhanced by previous treatment of the cells with interferon (priming), whereas the second response decreased after interferon treatment in a dose-dependent manner. The early response diminished with decreasing multiplicities of infection, the magnitude of the second response in unprimed cells was relatively independent of the dose of NDV employed. The early interferon response was sensitive to inhibition by actinomycin D for only 1 hr after inoculation. In marked contrast, the second response remained sensitive to inhibition by actinomycin D until 12 hr after inoculation. The ability of NDV to induce the second response was greatly diminished by irradiation of the virus with ultraviolet light or by its treatment with hydroxylamine, whereas the ability to stimulate the early response was relatively resistant to these virus-inactivating treatments. Treatment of NDV with hydroxylamine abolished the virus to induce the second response at the same rate as it destroyed infectivity. The results suggest the existence of at least two distinct mechanisms of interferon induction by NDV; the early response is triggered either by a virion component or by a product of primary transcription, whereas induction of the second response requires the expression of some functions of the virus not needed for triggering the early response.

Animals↗