Purification of mouse L cell interferon. Essentially pure preparations with associated cell growth inhibitory activity

Antitumor effects of human recombinant interferon-gamma and tumor necrosis factor on five cervical adenocarcinoma cell lines, in vivo and in vitro

We examined the antitumor effects of recombinant interferon-gamma (IFN-gamma) and tumor necrosis factor (TNF) on cervical adenocarcinoma cell lines, in vitro and in vivo. Four of five cell lines showed a high sensitivity to IFN-gamma, in vitro. One of five cell lines showed a remarkable sensitivity to TNF, in vitro. Only one cell line resistant to both IFN and TNF was derived from a well-differentiated adenocarcinoma of endocervical type. Experiments using nude mice bearing transplanted tumors revealed that these cytokines were also effective against tumors in vivo. All these observations suggest that IFN-gamma or TNF can have positive effects in the treatment of patients with adenocarcinoma of the uterine cervix.

Purification and carbohydrate structure of natural murine interferon-beta

Mouse interferon-beta (Mu-INF-beta) induced in C-243 cells with Newcastle disease virus was purified in four steps including ammonium sulfate fractionation. DEAE-cellulose, monoclonal Mu-IFN-beta antibody affinity and Mono-S cation-exchange chromatographies. Specific activity of the purified Mu-IFN-beta ranged over 1.1-1.4 X 10(9) NIH units/mg protein. This preparation was submitted to pronase digestion and gel on Fractogel TSK HW-40. The permethylated and acetylated glycopeptide fraction was analyzed by chemical-ionization (ammonia) mass spectrometry. The major glycopeptide is composed of Gal, Man, GlcNAc and NeuAc with a molar ratio of 2.0:3.6:3.4:0.5. The GLC pattern of methyl derivatives obtained by methanolysis and acetylation of fully methylated glycopeptide identified 2,3,4,6-tetra-O-methylgalactose; 3,4,6-tri-O-methyl-mannose; 2,3,4- and 2,4,6-tri-O-methylgalactose; 2,4,di-O-methyl mannose and 3,6-di-O-methylglucosamine. These results when compared with data on N-glycans suggest the following structure for the carbohydrate moiety of Mu-INF-beta: (formula; see text).

Do the interferons act singly or in combination?

Our views of interferon production and action have evolved from the simple to the complex. We review evidence that interferon-gamma (IFN-gamma) may induce a portion of its antiviral activity through the induction of another interferon. This is shown by demonstrating IFN-alpha in the supernatant fluids of IFN-gamma-treated mouse cells and showing that, under certain conditions, the antiviral activity of IFN-gamma in mouse and human cells can be reduced by antibody to IFN-alpha or IFN-beta, respectively. Induction of mouse spleen, bone marrow, and peritoneal exudate cells also results in their production of IFNs-alpha and/or -beta. In addition, new preliminary data indirectly suggests the presence of IFN-gamma in poly(IC):poly(LC)-treated mouse cells. In both of these systems, the maximal antiviral activity appears to develop as a consequence of the induction of a second interferon.

Analysis of the interferons induced in mice in vivo and in macrophages in vitro by Newcastle disease virus and by polyinosinic-polycytidylic acid

C57BL/6 mice or pure cultures of their macrophages were inoculated with Newcastle disease virus (NDV) or poly(I).poly(C) to induce interferons (IFNs) that were separated on CH-Sepharose 4B columns. The elution profiles of different activity peaks were compared. All preparations induced in vivo showed the same pattern but the relative proportions of the IFN activities varied. In vitro poly(I).poly(C)-induced IFN showed two peaks after separation by the column, and three peaks were found when NDV-induced IFNs were separated. When IFN induced by NDV in vitro was used to determine the molecular weight, activities were observed in three molecular weight ranges. The smallest one with 18,000 daltons was neutralized by anti-IFN-alpha and represented about 7% of the total activity. The activities of molecular weights 24,000 daltons and 29,000-31,000 daltons were neutralized by anti-IFN-beta. Poly(I).poly(C)-induced IFN in vitro showed two molecular weight ranges, 26,000 daltons and 40,000 daltons, and both were neutralized by anti-IFN-beta. IFN induced in serum by NDV at 3 h had molecular weights of 18,000 daltons neutralized by anti-IFN-alpha and 26,000-30,000 daltons neutralized by anti-IFN-beta. Both IFN subtypes were represented at equal quantities. Serum IFN found in the serum after 8 h had three molecular weight ranges: 18,500-19,500 daltons neutralized by anti-IFN-alpha containing 80% of the total IFN amount, 26,000-27,000 daltons, and 38,000 daltons both neutralized by anti-IFN-beta and containing 20% of the IFN.(ABSTRACT TRUNCATED AT 250 WORDS)

A high-yield chromatographic method for the purification of rat fibroblast interferon to a high specific activity

Rat fibroblast interferon (RfIFN), produced in serum-free media, has been purified 2,000-fold to 88% purity by a simple method that involves only two chromatographic steps: controlled pore glass and phenyl agarose chromatography. Over 70% of the initial activity was recovered. Gel electrophoresis (SDS-PAGE) and silver staining of the purified RfIFN revealed two major bands of RfIFN activity corresponding to Mr of 26,000 and 22,500 daltons, respectively. A very small amount of RfIFN was also recovered from a region of the gel corresponding to a Mr of 18,500. The average specific activity of the purified material was 3.7 X 10(8) U/mg. From these results it can be calculated that the specific activity of homogenous RfIFN is 4.0 X 10(8) U/mg.

Potentiating effect of murine interferon-gamma-containing lymphokine preparations on the antiviral and antiproliferative effects of murine interferon-alpha/beta: identification of the potentiation factor as murine interferon-gamma itself

Mixed preparations of murine interferon-gamma (MuIFN-gamma) and murine interferon-alpha/beta (MuIFN-alpha/beta) have been shown to induce more than additive levels of antiviral protection, when compared to those induced by these interferons given separately. MuIFN-gamma preparations contain many lymphokines and several of these as well as MuIFN-gamma itself may participate in this potentiation. In the present study, natural as well as three recombinant DNA-derived MuIFN-gamma's, in combination with antibody to MuIFN-gamma have been employed to examine the precise role of MuIFN-gamma. The antiviral effect was examined with a single cycle virus yield reduction assay and the antiproliferative effect with a colony formation inhibition assay. Recombinant DNA-derived MuIFN-gamma was as effective as natural MuIFN-gamma at participating in the potentiation of both the antiviral and antiproliferative activities. Antibody to MuIFN-gamma effectively blocked the potentiation of both the antiviral and the antiproliferative activities of natural and recombinant DNA-derived MuIFN-gamma's. Since the recombinant DNA-derived preparations from E. colie can be assumed not to contain mammalian proteins other than MuIFN-gamma, the data conclusively demonstrate that the potentiation factor in MuIFN-gamma preparations is MuIFN-gamma itself.

Inhibition of cell proliferation by interferons. 1. Effects on cell division and DNA synthesis in human lymphoblastoid (Daudi) cells

Treatment of Daudi cells with human lymphoblastoid interferons for up to 5 days progressively inhibits cell proliferation. For the first 3 days cells continue to grow but with prolonged doubling times; subsequently, net proliferation ceases and is accompanied by a loss of cell viability. We have investigated the changes in labelling of DNA with radioactive precursors which occur during the first phase of the response to interferon treatment. We have shown previously [Gewert et al. (1981) Eur. J. Biochem. 116, 487-492] that inhibition of incorporation of [3H]thymidine into DNA can be accounted for by impairment of thymidine transport and thymidine kinase activity. In spite of this inhibition, the total intracellular dTTP pool is larger in interferon-treated than in control cells. Because of these changes it has been necessary to use other methods to determine whether interferon treatment inhibits the overall rate of DNA synthesis. The results of experiments employing (a) moderately high thymidine concentrations or (b) incorporation of radioactivity from deoxynucleoside triphosphates into DNA in detergent-lysed or permeabilised cell systems indicate that there is in fact relatively little inhibition of the overall rate of DNA synthesis in cells exposed to up to 100 units/ml of interferons for at least 48 h. Furthermore, a similar proportion of cells incorporate [3H]thymidine in control and interferon-treated cultures and there is only a small decrease in the number of cells in S phase after interferon treatment, as revealed by fluorescence-activated cell sorting. These results indicate that cell proliferation may be regulated in this system by a mechanism in which there is a loss of coordination between the initiation of DNA synthesis and the subsequent events required for cell division.

Inhibition of anticellular activity of mouse gamma interferon by an inhibitor of interferon action

An inhibitor of interferon's (IFN) antiviral action was evaluated for its ability to block interferon's anticellular action. Crude and partially purified mouse immune interferon (MuIFN-gamma) preparations with high and low levels of an inhibitor of IFN's antiviral action were prepared. These preparations were examined for their relative antiviral and direct anticellular activities. The inhibitor present in the IFN-gamma preparations was found to be an equally potent inhibitor of both the antiviral and the direct anticellular activities of IFN-gamma. Further, while the inhibitor of IFN-gamma was inherently present in most IFN-gamma preparations, it was not an inherent feature of all IFN-gamma molecules. Inhibitor-free IFN-gamma could be separated from inhibitor-containing IFN-gamma by column chromatography. The results suggest that the inhibitor generally antagonizes interferon action and should be taken into account when evaluating the biological properties of IFN-gamma preparations.

Inhibition of cell division and antibody secretion by murine alpha/beta interferon: effects on plasmacytoma and hybridoma lymphoid cells

Murine alpha/beta interferon (IFN) inhibited the growth of myeloma cells in vitro. Independently of the cell growth inhibition, IFN also reduced the number of antibody secreting myeloma cells as measured by haemolytic plaque assay. The sensitivity of both MOPC 315 plasmacytoma cells and 4F4 hybridoma cells varied, though not to the same extent, depending on the dose of IFN used and the duration of exposure. Inhibition of PFC activity was observed after one day of IFN treatment while inhibition of cell growth was not detected until Day 2 of incubation. A dose of 20 u/ml IFN had no effect on the growth rate of MOPC 315 cells but with 100 u/ml the inhibition of growth was virtually complete. In contrast, an inhibition of PFC activity was observed at all the concentrations tested. The cell growth and PFC activity of 4F4 hybridoma cells, on the other hand, were both inhibited by IFN when used at concentrations as low as 1.25 u/ml. Incubation with higher concentrations of IFN resulted in a progressive reduction in cell growth and PFC activity of 4F4 cells, however to a lesser degree of inhibition compared to that observed with MOPC 315 cells. For example, although virtually 70% of MOPC 315 PFC could be inhibited by culture for two days in the presence of 100 u/ml, it was necessary to use 1,250 u/ml IFN for 4 days incubation before the similar level of PFC inhibition was achieved with 4F4 cells. IFN treatment resulted in an increase in both cellular volume and protein content and this effect was prevented when IFN was previously neutralised by a specific antiserum. IFN-treated cells also showed an inhibition in the incorporation of 3[H]-thymidine but no alteration in the rate of utilization of 35[S]-methionine, when compared with an equal number of control cells.

Large-scale, one-step purification of murine interferon-beta using a monoclonal antibody

A monoclonal antibody against murine interferon-beta (MuIFN-beta) was prepared using standard methods. Antibodies were immobilized by coupling to Sepharose and used for large-scale purification of poly(I) . poly(C)-induced mouse L cell IFN. Antibodies isolated from the serum of one nude mouse which was transplanted with the anti-MuIFN-beta antibodies producing hybridoma were able to bind at least 7 X 10(7)U MuIFN-beta. In one single antibody affinity chromatography step MuIFN-alpha was separated from MuIFN-beta and a 1000-fold purification of MuIFN-beta was obtained. The purified material had a specific activity of 5 X 10(8)U/mg protein. The recovery from the antibody column was 100%. SDS-PAGE analysis of the purified material revealed the presence of one single protein band with a molecular weight of 33 kD, representing MuIFN-beta.

Radioactive human lymphoblastoid interferon. One-step purification, regulation of heterogeneous species production and its use for radioimmunoassay

Human lymphoblastoid interferon (alpha type), labeled with [3H]leucine added to virus-induced Namalwa cells, was purified quantitatively and in one step from the culture fluid by immune precipitation. The material showed, upon polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, only four radioactive bands with molecular weights ranging from 17000 to 21000, which coincided well with interferon activity. They coincided also with the four interferon protein bands in the electropherogram of unlabeled interferon purified by a different method. The purity of the labeled interferon was ascertained also by polyacrylamide gel electrophoresis in the absence of dodecyl sulfate. Pulse-labeling of interferon with [3H]leucine for 1 h at various times after induction indicated that the cells always synthesized and secreted the four interferon species in parallel during the interferon production period. Competitive radioimmunoassay for human interferon alpha was achieved by the use of purified radioactive interferon, anti-(interferon alpha) serum, and bacterial adsorbent. The immune precipitation of the labeled interferon was inhibited by unlabeled interferon alpha, and 100 international reference units of interferon alpha could be measured in this way.

Ultrastructural localization of interferon receptors on the surfaces of cultured cells and erythrocytes

The bindings sites for interferon (IFN) on the limiting cell membranes of human and mouse fibroblasts and erythrocytes were revealed by an indirect immunoferritin technique. Mouse IFN-beta and human IFN-beta of high specific activity were used with the corresponding purified antibodies. Species-specific IFN binding was demonstrated by ferritin deposition on human erythrocytes and fibroblast membranes treated with human IFN and on mouse erythrocytes and fibroblast membranes treated with mouse IFN, but not on human erythrocytes or fibroblast membranes treated with mouse IFN. IFN binding sites on fibroblasts were located on regions of membranes between microvilli, whereas diphtheria toxin receptors were demonstrated mainly on microvilli. IFN binding altered the diphtheria toxin after IFN treatment. This reduced toxicity correlated with a decrease in the quantity of receptors for diphtheria toxin on the cell membrane. Thus, the species-specific binding of IFN appears to depend on membrane receptors in discrete regions of the limiting membrane which are present not only on functionally responsive fibroblasts but also on erythrocytes.

Interferon production in mixed cultures of mouse spleen cells and tumor cells: IFN-gamma as the main component

Interferon (IFN) production in mixed cultures of mouse spleen cells and tumor cells was investigated, mainly using mouse myeloid leukemic cells, M1, and spleen cells from syngeneic SL mice. Spleen cells from other mouse strains (C57BL/6, BALB/c nude and C57BL/6 beige) and other tumor cells (L929 and YAC-1) were similarly effective for IFN production, but mouse mammary carcinoma FM3A cells were not. As the IFN-inducing stimulus, mycoplasma contaminating the tumor cells, or endogenous retrovirus in them, may possibly be involved. The type of IFN produced was identified as IFN-gamma as a major component and IFN-alpha and -beta as minor ones, by acid stability tests and neutralization by antisera with defined specificities against alpha, beta, and gamma. Depletion of natural killer cells from spleen cells did not appreciably affect IFN production, but depletion of Thy 1.2 antigen-bearing cells greatly reduced IFN-gamma production, indicating that T cells were the main IFN producers.

Antigenic cross-reaction between the alpha types of human and mouse interferon

Cross-neutralization of the alpha and beta types of human and mouse interferons was tested using antibodies directed against the heterologous types of interferons. The alpha type of mouse interferon (MuIFN-alpha) prepared from L cells was found to be completely neutralizable by high-titered antibody against human alpha-type interferon (HuIFN-alpha), although the titers were much lower than those obtained in neutralization reactions with the homologous interferon. MuIFN-alpha from virus-induced lymphocytes, as well as non-glycosylated MuIFN-alpha from L cells, reacted similarly. The cross-reaction was also observed by the binding of anti-HuIFN-alpha antibody to a column of immobilized MuIFN-alpha. The binding experiment indicated that only a small fraction of the anti-HuIFN-alpha antibody population is heterologous reactive. Reciprocally, HuIFN-alpha from L cells, again with relatively low antibody titers, and the antibody responsible for the heterologous reaction was shown to be the anti-MuIFN-alpha and not anti-MuIFN-beta type. It is concluded that the alpha types of human and mouse interferon bear an antigenic homology. On the other hand, no significant antigenic cross-reactivity has been detected between the beta types of human and mouse interferons.

Studies with pure mouse Ehrlich ascites tumor interferons alpha and beta: patterns of induction of (2'-5') (A)n synthetase and of a double-stranded RNA-dependent protein kinase in mouse cells and human cells

The N-terminal sequences of mouse Ehrlich ascites tumor cell IFN beta (35,000-40,000 daltons) and IFN alpha (20,000 daltons) differ in 18 out of 20 positions. Furthermore, these two IFN species show little immunological cross reactivity. We treated mouse L929 cells and human HeLa S3 cells with essentially pure mouse IFN alpha or IFN beta or both at various concentrations and for various lengths of time. From the treated cells we prepared extracts and compared in these the activities of (2'-5')(A)n synthetase, an enzyme that was earlier shown to be induced by partially purified IFN preparations. The effects of treatment of mouse L929 cells with pure IFN alpha or IFN beta on (2'-5') (A)n accumulation in the cell extracts were very similar both in respect to the dependence on the length of exposure of the cells to the IFNs and on IFN concentration. Treatment with both IFN alpha and IFN beta at concentrations resulting in only partial induction of the enzyme led to an additive rather than to a synergistic effect. The maximal level of enzyme induced was the same in cells treated with high concentrations of IFN alpha or IFN beta or both. Mouse IFN alpha was as active as IFN beta in inducing a double-stranded RNA-dependent protein kinase in mouse L cells. The treatment of HeLa S3 cells with IFN beta did not affect the accumulation of (2'-5') (A)n in their extracts whereas treatment with IFN alpha boosted the accumulation though to a lesser extent than in the case of mouse L cells. These results are in line with the finding that mouse IFN alpha can, but mouse IFN beta cannot convert HeLa S3 cells into the antiviral state and also with the more pronounced homology in N-terminal sequence between mouse IFN alpha and a human (lymphoblastoid) IFN chi than between mouse IFN beta and a human IFN beta.

Mouse interferons: amino terminal amino acid sequences of various species

Mouse interferons of three size classes (A, 35,000 to 40,000 daltons; B, 26,000 to 33,000 daltons; and C, 20,000 daltons) were purified from Ehrlich ascites tumor cells infected with Newcastle disease virus. The sequences of the first 24 amino acids (No. 17 has not been identified) of interferons A and B are identical. The sequence of the first 20 amino acids of interferon C differs from that of A and B in 18 positions. There is partial homology in amino terminal sequence between mouse interferons A (or B) and a human fibroblast interferon and between mouse interferon C and a human lymphoblastoid interferon.

Amino terminal sequence of the major component of human lymphoblastoid interferon

Homogeneous human lymphoblastoid interferon with an apparent molecular size of 18,500 daltons was characterized by its amino acid composition. Analysis of the amino terminal sequence by Edman degradation indicates that the sequence is unique.

An analysis of neutralization reaction of interferon by antibody: a proposal on the expression of neutralization titer

Methods of determining and expressing the neutralization titer of anti-interferon antibody were discussed based on considerations of the mass-action law and on experimental data of neutralization of L cell interferon by various antisera. The antibodies in all the sera so far examined were inferred to have low affinities (low association constants compared to the reciprocal of molar concentrations of free interferon), regardless of whether the serum had a low (a few hundred) or high (over 10(5) titer. Then the equilibrium equation can be approximated by a simple formula which relates the antibody concentration to the ratio of total to free interferon concentrations; the absolute amount of interferon neutralized (the difference between total and free interferons) is not involved in computing the titer, and therefore the problem of variations in interferon sensitivity in different assays is eliminated. It is proposed that the neutralization titer be defined, not as the antibody dilution that neutralizes a certain quantity of interferon (such as 10 international units, as often found in the literature), but as the dilution that reduces the interferon titer by a certain factor (taken to be 10 in this paper). A simple formula for calculating the titer from experimental data is given.