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Interferon and spontaneous cytotoxicity in man. II. Studies in patients receiving exogenous leukocyte interferon.

The spontaneous cytotoxicity of peripheral lymphoid cells from five tumor patients was measured before and at various times after the first injection of human leukocyte interferon (IF). Four of the patients' lymphocytes exhibited cytotoxicity before the IF injection. After injection of IF there was an initial decrease in cytotoxicity, followed by an increase to 1.5-5 times above the preinjection level, the peak being reached at 12 hours. Thereafter the spontaneous cytotoxicity decreased but usually remained elevated for 24 hours after the injection. The lymphocytes of the fifth patient had very low spontaneous cytotoxicity before the injection of IF, and this did not markedly change afterwards. The proportion of E-rosette forming cells seemed to decrease slightly in all patients after the injection, followed by a normalization at 24-48 hours.

Adolescent↗

Mechanism of interferon action. Interferon alpha inhibits vesicular stomatitis virus primary transcript accumulation in P1/eIF-2 alpha protein kinase-deficient human fibroblast cells.

The molecular basis of the inhibition of vesicular stomatitis virus (VSV) replication by purified recombinant alpha interferon (IFN-alpha A/D) in human fibroblast GM2767A cells was examined. A saturating concentration of IFN-alpha A/D inhibited infectious VSV yield by about four to five log10. By use of the VSV mutant tsG41, which is competent in RNA transcription but defective in RNA replication at 40 degrees C, it was shown that IFN-alpha A/D treatment significantly inhibited primary viral protein synthesis. However, the apparent IFN-induced inhibition of VSV protein synthesis was due primarily to a reduction in the accumulation of VSV primary transcripts in IFN-alpha A/D treated GM2767A cells rather than to a direct effect on translation per se. The IFN-induced reduction in VSV primary genome expression was detectable after only 1 hour of IFN treatment; actinomycin D treatment of GM2767A cells prior to IFN-alpha A/D treatment blocked the establishment of the IFN-induced inhibition of VSV. In contrast to the results obtained with GM2767A cells, IFN-alpha A/D produced no detectable effect on the accumulation of VSV primary transcripts in human amnion U cells even though VSV primary protein synthesis and infectious virus yield were significantly reduced. In summary, the principal cause of the IFN-alpha induced inhibition of VSV replication in protein P1/eIF-2 alpha kinase-deficient human fibroblast GM2767A cells appears to be at or prior to primary transcript accumulation; thus, the antiviral mechanisms of IFN-alpha in GM2767A cells is fundamentally different from the IFN-alpha induced translation inhibition observed in kinase-sufficient human amnion U cells.

Amnion↗

Mechanism of interferon action: inhibition of vesicular stomatitis virus replication in human amnion U cells by cloned human gamma-interferon. I. Effect on early and late stages of the viral multiplication cycle.

The molecular basis of the inhibition of vesicular stomatitis virus (VSV) replication by pure recombinant gamma-interferon (IFN-gamma) in human amnion U cells was examined. A saturating concentration of IFN-gamma induced, at maximum, about a two log10 reduction in infectious VSV yield. The kinetics of induction of the antiviral activity by IFN-gamma were first order over the period of about 6-18 h, following a lag of about 3 h, after treatment with a saturating concentration of IFN-gamma. The relationship of the inhibition in VSV infectivity to the early and late events of the VSV multiplication cycle was investigated. IFN-gamma treatment had no detectable effect on the adsorption and penetration of VSV virions or on their uncoating to yield viral nucleocapsids. The polypeptides of adsorbed or uncoated VSV particles were neither preferentially degraded nor detectably altered in IFN-gamma-treated U cells, as compared to untreated U cells. Progeny virions isolated from IFN-gamma-treated U cells, although greatly reduced in number, were found to be equally as infectious as those isolated from untreated U cells. Progeny virions from IFN-gamma-treated cells also possessed the same composition of viral proteins as was observed for virions from untreated cells. These results suggest that conditions of IFN-gamma treatment sufficient to reduce the yield of infectious VSV progeny 100-fold do not detectably affect either the early or the late stages of the VSV multiplication cycle.

Amnion↗

Mechanism of interferon action: inhibition of vesicular stomatitis virus replication in human amnion U cells by cloned human gamma-interferon. II. Effect on viral macromolecular synthesis.

The effects of recombinant human gamma-interferon (IFN-gamma) on vesicular stomatitis virus (VSV) macromolecular synthesis in human amnion U cells were examined. Saturating concentrations of IFN-gamma caused only a 3 to 5-fold reduction of viral protein synthesis in wild-type VSV-infected cells, an extent insufficient to account for the 100-fold inhibition of viral infectivity. By use of the VSV mutant tsG41, which is competent in RNA transcription but defective in RNA replication at 40 degrees C, it was shown that the apparent IFN-induced inhibition of viral protein synthesis was likely due to a reduction in the synthesis of primary transcripts in IFN-gamma-treated U cells. Dot blot hybridization analysis revealed that saturating concentrations of IFN-gamma reduced both primary (measured with mutant tsG41-infected U cells) and total (measured with wild-type-infected U cells) viral RNA synthesis by about 4-fold, an extent of inhibition comparable to the observed reduction in viral protein synthesis. Analysis of RNA, fractionated by agarose gel electrophoresis after denaturation with glyoxal, with cDNA probes to individual VSV mRNAs did not reveal any detectable difference in the structural integrity of VSV mRNA isolated from IFN-gamma treated as compared to untreated U cells. These results suggest that IFN-gamma treatment causes a small reduction in the efficiency of transcript formation catalyzed by input parental virions. However, the results also indicate that the principal cause of the IFN-gamma-induced inhibition of VSV replication in U cells is the alteration of a step in replication other than viral macromolecular synthesis. This implies that the molecular mechanism of viral inhibition by IFN-gamma is fundamentally different from that of IFN-alpha in human amnion U cells.

Amnion↗

Experimental visceral leishmaniasis: production of interleukin 2 and interferon-gamma, tissue immune reaction, and response to treatment with interleukin 2 and interferon-gamma.

During the first 2 to 4 weeks of progressive visceral infection with the intracellular protozoan, Leishmania donovani, spleen cells from BALB/c mice failed in response to leishmanial antigen to produce either of the activating T cell-derived lymphokines, interleukin 2 (IL 2) or gamma-interferon (IFN-gamma). Four weeks after infection, however, antigen-induced IL 2 and IFN-gamma secretion emerged and coincided with the onset of control over parasite replication and the subsequent killing of greater than 80% of intrahepatic L. donovani. The development of this immunosecretory activity correlated with the hepatic tissue response at the site of parasitized Kupffer cells. This response progressed from Kupffer cell fusion (week 1) to fusion plus a mononuclear cell infiltrate (week 2) to well-organized granuloma formation (weeks 4 to 8). In contrast, T cell-deficient nude BALB/c mice exerted no control over L. donovani, their spleen cells failed to generate antigen-induced IFN-gamma, and at 4 weeks, their livers were devoid of any tissue reaction. Since spleen cells from 2-week infected normal mice did not produce antigen-stimulated IL 2 or IFN-gamma, these mice were treated with recombinant (r) lymphokines. Various protocols using both high and low dose human rIL 2 had no antileishmanial effect. Hepatic parasite replication was completely halted, however, by macrophage-activating doses of murine rIFN-gamma. These results reemphasize that an intact T cell-dependent response is required for successful defense against L. donovani, indicate that this immune response can be measured at both the cellular (secretory) and tissue levels, and confirm that IFN-gamma can exert an antileishmanial effect in vivo.

Animals↗

Mechanism of interferon action. I. Characterization of a 54-kDa protein induced by gamma interferon with properties similar to a cytoskeletal component.

A polypeptide of 54-kDa molecular mass (p54) induced by molecularly cloned human interferon gamma (rIFN-gamma) in human amnion U cells was characterized biochemically and immunologically. Rabbit polyclonal antibody to p54 was prepared using p54 purified from human amnion U cells as the immunogen. As measured by immunoprecipitation of [35S]methionine pulse-labeled extracts or by immunoblot analysis of unlabeled extracts, the synthesis of p54 was greatly elevated in three human cell lines treated with IFN-gamma, amnion U, fibroblast GM2767, and fibroblast F153. Moreover, the rabbit anti-p54 polyclonal antibody preparation cross-reacted with cytoskeleton-associated polypeptides prepared from human cells and from sea urchin embryos. By use of a monoclonal antibody probe directed against the common domain of intermediate filaments (anti-intermediate filament antibody), it was established that intermediate filament components are also induced by rIFN-gamma. Anti-p54 polyclonal antibody cross-reacted with anti-intermediate filament antibody-recognized, rIFN-gamma-induced polypeptides. Thus, it appears that p54 may be an IFN-induced cytoskeleton-associated polypeptide.

Animals↗

Interferon gamma in rheumatoid arthritis--a double blind study comparing human recombinant interferon gamma with placebo.

A double blind trial comparing recominant interferon gamma (IFN gamma) with placebo in rheumatoid arthritis is presented. Twenty-six patients entered the study and 22 completed the 6-month period. IFN gamma was administered subcutaneously as was placebo; the 1st week, patients treated with the active compound received a daily subcutaneous injection of 100 micrograms of IFN gamma and for the following 23 weeks the schedule was decreased to 2 injections of 100 micrograms every week. No serious side effects were observed. After Week 24 the group treated with the active compound showed a significant decrease of the joint tenderness score and the placebo group showed a significant increase of the number of subcutaneous nodules. All other variables shifted in favour of the active compound but not significantly. More double blind trials with a larger number of patients and using other treatment schedules or other routes of administration are required.

Arthritis, Rheumatoid↗

Differential gamma-interferon response of human colon carcinoma cells: inhibition of proliferation and modulation of immunogenicity as independent effects of gamma-interferon on tumor cell growth.

The effect of recombinant gamma-interferon (IFN-gamma) on established human colon carcinoma cell lines as well as fresh tumor cells from colon carcinoma patients has been investigated with respect to growth inhibition, enhancement of HLA expression, and modulation of immunogenicity. A direct antiproliferative activity of IFN-gamma was observed in five of seven cell lines tested, with a reduction of [3H]thymidine incorporation between 30 and 90%. Depending on the cell line, the IFN-gamma doses required for maximal inhibition varied between 20 and 2 X 10(4) units/ml. Independent of this effect, IFN-gamma enhanced the expression of HLA-A,B,C antigens in all cells investigated and induced expression of HLA-DR in three of seven carcinoma cell lines. Antigenic modulation of Class I and II major histocompatibility complex antigens was paralleled by an enhancement of the in vitro immunogenicity in three of four established carcinoma lines and in three of three cases, using cells derived from primary tumor cultures. Induction or enhancement of both proliferative and cytolytic T-cell responses was obtained in allogeneic and in autologous mixed-lymphocyte tumor cell cultures.

Adenocarcinoma↗

Inhibition of feline infectious peritonitis virus replication by recombinant human leukocyte (alpha) interferon and feline fibroblastic (beta) interferon.

Replication of feline infectious peritonitis virus (FIPV) in feline cell cultures was inhibited after incubation of cells with either human recombinant leukocyte (alpha) interferon (IFN) or feline fibroblastic (beta) IFN for 18 to 24 hours before viral challenge exposure. Compared with virus control cultures, FIPV yields were reduced by ranges of 0.1 to 2.7 log10 or 2 to 5.2 log10 TCID50 in cultures treated with human alpha- or feline beta-IFN, respectively; yield reductions were IFN dose dependent. Sensitivity to the antiviral activities of IFN varied with cell type; feline embryo cells had greater FIPV yield reductions than did similarly treated feline kidney or feline lung cells. Comparison of the virus growth curves in IFN-treated and virus control cultures indicated marked reduction in intracellular and extracellular FIPV in IFN-treated cultures. Compared with virus control cultures, intracellular and extracellular infectivity in IFN-treated cultures was delayed in onset by 12 and 30 hours, respectively, and FIPV titers subsequently were reduced by 3 to 3.5 and 5 log10 TCID50, respectively. Frequently, immunofluorescent and electron microscopy of IFN-treated cells or cell culture fluids did not reveal virus; however, even in cultures without viral cytopathic changes, small amounts of virus occasionally persisted in cells.

Animals↗

Synergistic interactions of interleukin 1, interferon-beta, and tumor necrosis factor in terminally differentiating a mouse myeloid leukemic cell line (M1). Evidence that interferon-beta is an autocrine differentiating factor.

The effect was investigated of combinations of cytokines known to be cytostatic for some tumor cells, namely interleukin 1 alpha (IL-1 alpha), interferon-beta (IFN-beta), and tumor necrosis factor (TNF), on the growth and differentiation of the mouse myeloid leukemic cell line, M1, cells. IL-1 alpha, IFN-beta, and TNF by themselves are antiproliferative for M1 cells. Treatment of cells with a mixture of any two of the three cytokines resulted in at least additive growth inhibition. None of these cytokines by themselves induced differentiation of M1 cells as assessed by increased expression of Fc receptors (FcR), stimulation of phagocytic activity and by morphologic criteria. However, as little as 1 U/ml IL-1 alpha in conjunction with IFN-beta or TNF increased FcR expression, phagocytic activity and morphologic changes in addition to inhibiting the growth of M1 cells. The combination of IFN-beta and TNF did not induce differentiation, although the growth of the cells was markedly inhibited. Both TNF and lipopolysaccharide (LPS) induced the in vitro production of IFN activity by M1 cells. Furthermore, the induction of differentiation of M1 cells by a combination of IL-1 alpha with either IFN-beta, TNF, or LPS was inhibited by antibody against mouse IFN-beta. Therefore, it appears that IFN-beta provides one of the two required signals for differentiation of M1 cells by these combinations of stimulants, the other being IL-1. Furthermore, the cytostatic effect of TNF by itself on M1 cells was also partly blocked by anti-IFN-beta antibody, suggesting that IFN-beta is also involved in the growth inhibitory effect of TNF for M1 cells. In contrast, the cytostatic effect of IL-1 on M1 cells was not blocked by anti-IFN-beta antibody. In conclusion, both the cytostatic and differentiative effect of TNF appear to be mediated by IFN-beta. Thus, the combination of IL-1 and IFN-beta or inducers of IFN-beta resulted in terminal differentiation of M1 cells. Northern blot analysis using cDNAs for murine IFN-beta1 or human IFN-beta2 showed an increased expression of mRNA for IFN-beta1 but not for IFN-beta2 by stimulation with TNF or LPS, strongly suggesting that IFN-beta 1 rather than IFN-beta 2 is responsible for TNF or LPS effects.

Animals↗

The role of interferon-beta 1 and the 26-kDa protein (interferon-beta 2) as mediators of the antiviral effect of interleukin 1 and tumor necrosis factor.

This study confirms our earlier finding that human interleukin (IL)-1 beta exerts an antiviral effect on diploid fibroblasts and on MG-63 osteosarcoma cells. It also extends the observation in that a similar effect was noted on aged but not freshly trypsinized HEp-2 cells, and that not only IL-1 beta but also IL-1 alpha and tumor necrosis factor (TNF)-alpha exerted similar antiviral effects on cells. The antiviral effects of these cytokines were neutralized by addition to the assay system of an antibody that was specific for interferon (IFN)-beta 1, indicating that IFN-beta 1 or a structurally or functionally related substance is involved in the antiviral activity observed. Both IL-1 and TNF were able to induce production of the 26-kDa protein, also known as IFN-beta 2, hybridoma/plasmacytoma growth factor (HPGF) or B-cell stimulatory factor-2 (BSF-2) and previously proposed as an alternative to IFN-beta 1 for mediating the antiviral effect of TNF. However, no good correlation was found between the antiviral effects of TNF and its potential to induce production of the 26-kDa protein. Furthermore, the anti-IFN-beta 1 serum which neutralized the antiviral activity of IL-1 and TNF did not cross-react with the 26-kDa protein. Conversely, the antiviral effect of IL-1 and TNF was only weakly neutralized by an antibody that did react with the 26-kDa protein and showed low cross-reactivity with IFN-beta 1. These observations, together with the low specific activity of the 26-kDa protein as an antiviral agent (less than 10(5) U/mg protein) provide strong arguments against this protein and in favor of IFN-beta 1 (or still another IFN-beta 1-related molecule) as the ultimate mediator of the antiviral effect of IL-1 and TNF.

Antiviral Agents↗

Expression of human interferon alpha H, an interferon with two potential asparagine-linked glycosylation sites.

Of the large number of human alpha interferon genes identified, only one, Hu-IFN-alpha H, contains potential asparagine-linked glycosylation sites. With the use of a new vector that permits convenient expression, site-specific mutation, and DNA sequencing, Hu-IFN-alpha H was expressed in Escherichia coli. The bacterial product which is not glycosylated is fully active demonstrating that the carbohydrate on this species is not required for antiviral activity.

Asparagine↗

Clinical phase II trial of recombinant DNA interferon (interferon alpha 2b) in patients with metastatic malignant melanoma.

Twenty-four patients with histologically proven metastatic malignant melanoma were included in a Phase II trial of human DNA recombinant interferon (rDNA IFN alpha 2). They were given 10 X 10(6) IU of IFN alpha 2 subcutaneously three times a week until progression of disease or major intolerance developed. Twenty-two patients were evaluable for toxicity and response. General manifestations of intolerance were seen in all the patients. Hematologic toxicity was seen in six patients and therapy had to be interrupted in one patient. Mild liver toxicity was seen in most patients after 2 weeks of treatment. These manifestations disappeared within 2 weeks after treatment was discontinued. A partial response was seen in four cases lasting 2, 4, 4, and 5 months, respectively. There were two complete responses (one skin, one lymph node metastasis) lasting 20 and 6 weeks, respectively. These results indicate a potential role for rDNA IFN alpha 2 in treating patients with metastatic malignant melanoma. However, further trials are required to determine the optimal dose and schedule of administration and modalities of combination.

Adult↗

Development of interferon-specific monoclonal antibody for in vitro interferon assays.

In this study, monoclonal antibodies (MABs) to human interferon alpha (HuIFN alpha) were evaluated for their suitability for the quantification of different HuIFN alpha preparations by conventional immunoassay methods. The results obtained using four different MABs were compared and suggest that whilst immunoassays can be highly sensitive and reproducible to perform, calibration of antigen content in relation to units of biological activity remains a problem, particularly because of the molecular and biological heterogeneity of HuIFN alpha preparations. Nevertheless, the judicious selection of MABs specific for an individual HuIFN alpha subtype has indicated that immunoassays may be accurately calibrated in units of biological activity for potency estimations of that HuIFN alpha subtype.

Antibodies, Monoclonal↗

Immunoregulatory effects of interferon-alpha. I. Interferon-alpha inhibits in vitro antibody synthesis by normal human lymphocytes.

The effects of human interferon-alpha (IFN-alpha) on in vitro synthesis of specific anti-influenza virus antibody were measured in cultures of peripheral blood lymphocytes from normal donors. IFN-alpha suppressed antibody synthesis in a time and dose related manner. This suppression was also produced by monoclonal antibody purified IFN-alpha and was blocked by anti-IFN-alpha antibody. However antibody induced by a combination of antigen and 'B cell helper supernatant' was not suppressed indicating that IFN-alpha inhibits the initial events in antibody synthesis but does not affect cells committed to antibody production.

Adult↗

Establishment of the antiviral state in alpha, beta-interferon-resistant Friend cells treated with gamma-interferon. Induction of 67-kilodalton protein kinase activity in absence of detectable 2-5A synthetase.

Treatment with murine gamma-interferon (IFN) preparations of variant sublines of Friend leukemia cells resistant to the alpha, beta IFN-induced antiviral state (Affabris, E., Jemma, C., and Rossi, G.B. (1982) Virology 120, 441-452; Affabris, E., Romeo, G., Belardelli, F., Jemma, C., Mechti, N., Gresser, I., and Rossi, G. B. (1983) Virology 125, 508-512) results in the establishment of a bona fide antiviral state. In fact, gamma IFN preparations are able to induce a dose-dependent reduction of endogenous virus release and of vesicular stomatitis or encephalomyocarditis viruses yields (up to 1.5 log). Under these experimental conditions, no inducible 2-5A synthetase activity is detectable in cell extracts. The 67-kDa protein kinase, uninducible by treatment with alpha, beta IFN (up to 13,000 units/ml), is instead induced upon treatment with gamma IFN at a similar rate of activity as in wild-type Friend leukemia cells, both when assayed in solution and after immobilization on poly(rI) X poly(rC)-agarose.

2',5'-Oligoadenylate Synthetase↗

Macrophage activation to kill Leishmania major: activation of macrophages for intracellular destruction of amastigotes can be induced by both recombinant interferon-gamma and non-interferon lymphokines.

Macrophages treated with lymphokine (LK)-rich culture fluids from antigen- or mitogen-stimulated spleen cells or the hybridoma T cell 24/G1, or murine recombinant interferon-gamma (IFN-gamma) from either transfected monkey kidney cells (cos rIFN-gamma) or bacterial (E. coli) DNA (rIFN-gamma) developed the capacity to kill intracellular amastigotes of Leishmania major. Removal of IFN activity from LK by neutralizing fluid phase monoclonal anti-rIFN-gamma antibody, or by solid phase immunoadsorption, left residual macrophage activation factors that induced approximately 50% of the macrophage anti-leishmanial activity of untreated LK. In contrast, rIFN-gamma subjected to the same antibody treatments lost all capacity to induce this macrophage effector function. These results suggest that the intracellular destruction of amastigotes is regulated by several different factors. One of these factors is clearly IFN-gamma, which is pleiotropic in its effects on macrophage functions. The other non-IFN LK factors are immunochemically unrelated to IFN-gamma, and may regulate macrophage microbicidal activities in a more selective manner.

Animals↗

Differential modulation by recombinant immune interferon of the expression and shedding of HLA antigens and melanoma associated antigens by a melanoma cell line resistant to the antiproliferative activity of immune interferon.

By culture of human melanoma Colo 38 cells in the presence of increasing concentrations of recombinant immune interferon (IFN-gamma), the clone RZ gamma-4G.1 resistant to the antiproliferative action of IFN-gamma (3 X 10(4) units/ml) was isolated. This clone was cultured for 6 weeks in the absence of IFN-gamma and was subsequently treated with increasing concentrations of IFN-gamma. Contrary to the response of its parental cell line, treatment of this clone with IFN-gamma did not significantly alter the rate of protein or DNA synthesis and did not markedly modulate the cell surface expression of HLA Class I antigens, of the high molecular weight melanoma associated antigen, and of a Mr 100,000 melanoma associated antigen. IFN-gamma caused an increase in the cell surface expression and in the shedding of HLA Class II antigens from IFN-gamma resistant cells. Four proteins with molecular weights of 32,000, 38,000, 46,000, and 50,000 were induced by IFN-gamma in the parental melanoma cells but not in the resistant clone. Both cell lines bound equivalent amounts of 125I-IFN-gamma to their surface, indicating that the lack of specific surface receptors was not the cause of insensitivity to IFN-gamma. These results indicate that at the cellular level IFN-gamma modulates the expression and shedding of HLA Class II antigens through different mechanisms to those responsible for the antiproliferative action, modulation of the cell surface expression of melanoma associated antigen and of HLA Class I antigens, and induction of new proteins in cultured melanoma cells. Since the success of therapy of malignant diseases with IFN-gamma depends on the extent of resistance of individual tumor cells, the present study may provide a better understanding of the biology of IFN-gamma insensitive tumor cells and particularly the malignant melanoma.

Animals↗