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L Borecký

Publications and source records attributed to L Borecký.

At least 19 recordsLinked to original sources
PubMed1991

Distinct effect of pH 2 on a common antigenic structure found in human interferons-alpha 1 and -alpha 2 in the region 30-35.

The antigenic similarity between molecules of recombinant human interferon-alpha 1 (IFN-alpha 1) and recombinant human IFN-alpha 2 was demonstrated with neutralizing monoclonal antibody (mAb) 1-46. The common epitope for the mAb 1-46 was localized into amino-terminal region of IFN-alpha molecule around residues 30-35. Following pH 2 treatment, the biological activity of both IFN-alpha 1 and IFN-alpha 2 was retained but the antigenic relatedness between corresponding sequences 30-35 was diminished. The common structure on the IFN-alpha 1 molecule proved acid stable and the mAb 1-46 retained the ability to neutralize the pH 2 treated IFN-alpha 1. However, the neutralization of pH 2-treated IFN-alpha 2 by specific antibody was completely suppressed. These results complemented our earlier finding of the dramatic effect of acidic pH on the antigenic structure of region 132-137 of the IFN-alpha 2 molecule. We conclude that pH 2 may induce a conformational rearrangement of the IFN-alpha 2 molecule, resulting in an altered tertiary structure with deviating antigenic characteristics.

Acids↗
PubMed1991

Enhancement of neutralizing efficacy by combining three monoclonal antibodies to human interferon-alpha.

Three murine monoclonal antibodies (mAb) directed to distinct epitopes on recombinant human interferon (IFN)-alpha 1, and three mAb recognizing distinct epitopes on recombinant human interferon (IFN) alpha 1, and three mAb recognizing distinct epitopes on recombinant human IFN-alpha sc, were studied by IFN-neutralizing assays. The efficacy of neutralization of the anti-viral and the anti-proliferative activities of IFN-alpha 1, or IFN-alpha 2c, by the specific antibodies used, individually or in combination, were evaluated. In comparison with single mAb, the mixtures of three mAb against IFN-alpha 1 or three mAb against IFN-alpha 2c were capable of neutralizing more than 10-times larger amounts of IFN-alpha 1 and alpha 2c, respectively. The strong potentiation of the neutralization efficacy resulting from mixing different mAb was demonstrated by neutralization of the anti-viral as well as the anti-proliferative activities of both recombinant IFN. The neutralization experiments support the interpretation that the observed potentiation results from simultaneous interaction of anti-IFN mAb with different epitope specificity.

Antibodies, Monoclonal↗
PubMed1990

Antigenic link between human interferons-alpha and -beta: the common epitope 1.

An until now unobserved consistent antigenic structure, tentatively named "common epitope 1," was detected on molecules of human recombinant (rHu) IFN-alpha 2 and natural HuIFN-beta by testing with monoclonal and polyclonal antibodies. The monoclonal antibody B6, obtained after immunization of BALB/c mice with human fibroblast IFN-beta, was capable of binding and neutralizing both IFN-alpha 2 and natural IFN-beta. The neutralizing activity of monoclonal antibody B6 was completely inhibited by a synthetic hexapeptide which corresponded to the amino acid sequence of IFN-alpha 2 in positions 132-137. Although a corresponding sequence of amino acids in the IFN-beta molecule was localized to the region 134-139 and shows only a 66% homology with the assumed IFN-alpha 2 binding site, lysine at position 132 in IFN-alpha 2 and at position 134 in IFN-beta seems to be crucial for establishment of the common epitope. Its existence was supported by experiments using polyclonal antibodies. Antiserum to IFN-alpha 2 showed cross-neutralization with IFN-beta, and vice versa, antiserum to IFN-beta cross-reacted with IFN-alpha 2. The ability for cross-neutralization by both polyclonal antisera was abolished in the presence of IFN-alpha 2 hexapeptide SH 132-137. No cross-reacting epitope could be detected on the IFN-alpha 1 molecule. These findings are the first evidence of a homology between human IFNs of alpha and beta types at the antigenic level. They indicate that the antigenic distinction between IFNs of alpha and beta types is not absolute.

Amino Acid Sequence↗
PubMed1990

Modification of the antigenic structure of human interferon alpha-2 by PH 2 treatment: a further support for the antigenic relationship between alpha and beta interferons.

We have recently reported that a unique antigenic structure, designated as Common epitope 1, was found to be shared by human recombinant IFN alpha-2 and the human fibroblast IFN beta. The Common epitope 1 was identified with the aid of a synthetic IFN alpha-2 fragment SH 132-137. Based on this observation, we proposed the hypothesis that an antigenic relationship should exist also between natural human leukocyte IFN alpha and natural human fibroblast IFN beta. However, we were not able to detect any Common epitope 1 in preparations of conventional human leukocyte IFN alpha. In the present study, we were looking for a possible explanation of absence of the Common epitope 1 in conventional leukocyte IFN alpha. First, we demonstrated its acid labile nature in the recombinant IFN alpha-2 molecule and second, we proposed that the pH 2 lability of this unique epitope might be responsible for the lack of antigenicity also in pH 2-treated (conventional) leukocyte IFN alpha preparations. Actually, when pH 2 non-treated leukocyte IFN alpha was examined, we succeeded in demonstration of the Common epitope 1 in IFN-preparation. Moreover, anti-serum against pH 2 non-treated IFN alpha was capable of neutralizing both the conventional i.e. pH 2-treated leukocyte IFN alpha and fibroblast IFN beta. It is concluded that the nomenclature distinguishing two classes (i.e. alpha and beta as class I and gamma as class II) of IFNs is more appropriate than the current official nomenclature distinguishing three antigenic classes of IFNs.

Animals↗
PubMed1979

Production of antiviral and migration inhibitory activities in the peritoneum of mice after inoculation with allogenic Ehrlich ascites tumor cells.

Peritoneal inoculation of Ehrlich ascites cells into mice stimulates the appearance of migration inhibitory factor (MIF) not only in the peritoneum but also in the circulation of mice. Whereas the MIF-activity in the peritoneum reached maximum at 6 days and disappeared within 17 days, the MIF-activity of sera reached maximum levels at about 11 days after intraperitoneal inoculation of tumor cells (10(6) of EAC per mouse). In addition, an antiviral activity of peritoneal exudates was observed in the early stage (24--72 h) of tumor challenge. The time-course of appearance of both MIF and AV-inhibitor are presented. A significant decrease of MIF-activity was noted when the tumor-inoculated mice were treated with ds-RNA, antithymocyte serum and cyclophosphamide, respectively. The appearance of antiviral activity in the peritoneum of tumor-inoculated mice seems to be macrophage-dependent. Although the antiviral factor meets several criteria of interferons, further studies are required for its characterization.

Animals↗
PubMed1979

Production of human leukocyte interferon for clinical use under immunoelectrophoretic control.

Human leukocyte interferon (HLIF) can be contaminated by several antigens which may include also potentially pathogenic agents. For this reason, gel filtration as a separation method was included into the routine procedure of preparation and purification of HLIF for clinical use. Since production of HLIF requires the cultivation of leukocytes in the presence of serum (or albumin), serum proteins represent then the majority of proteins contaminating IF preparations. Measuring the total protein content, as a control of various antigens present in HLIF preparations during purification, becomes ineffective because, essentially, it indicates only the decrease of the amount of proteins derived from cultivation medium. For a better visualization of dissociation of different antigens from molecules with IF activity during the purification procedure, the method of quantitative immunoelectrophoresis was applied utilizing a sheep antiinterferon serum in assay. Our results indicate that this method represents a valuable control test.

Animals↗
PubMed1979

Antiviral and anticellular effects of interferon on the mouse embryonic cells transformed by viruses and/or chemical carcinogen.

The antiviral and anticellular activity of partially purified mouse interferon has been tested in cell lines transformed with Simian Virus 40 (MEB-SV 40), mouse sarcoma virus (Harvey strain) (MEB-MSV), and 20-methylcholanthrene (MEB-MCH), respectively. The transformed lines were derived from C3H mouse embryonic primary cells. It has been shown that the MEB-MSV cells were 10 to 50 times less sensitive to the antiviral effect of interferon than the MEB-SV 40 or MEB-MCH cells. A 30% reduction of the number of treated cells as compared with untreated control cells was taken as basis for comparison of anticellular activity of interferon in transformed lines. While the MEB-MCH cells required 1000 units of interferon for a 30% growth inhibition, about 3000 units were necessary for a comparable suppression of MEB-SV 40 cells and/or MEB-MSV cells.

Agglutination↗
PubMed1979

The effect of interferon induction on complement level in rat.

Relatively high levels of interferon were achieved in rat sera by intracardial inoculation with Sindbis virus followed 15 min later by intraperitoneal application of dimethylsulfoxide. At intervals when interferon titres reached the maximum, the levels of complement were decreased as compared with the control group of rats. Single administration of dimethylsulfoxide did neither induce interferon nor influence the complement levels in sera of rats of the Dobrá Voda breed tested. Similar results were obtained with concentrated Newcastle disease virus inoculated intraperitoneally. Of interest is the finding that properdin levels seem to increase at the same time as interferon.

Animals↗
PubMed1979

Long-term culture of guinea pig tongue cells: a suitable interferon system.

The interferon system was investigated in a long-term culture of guinea pig tongue (GPT) cells. Interferon synthesis was induced with Newcastle disease virus (B strain) and f2 phage double-stranded RNA. Guinea pig interferons were about 2 times more active in cell cultures established from guinea pig embryos than in the GPT cells. Human leukocyte and mouse peritoneal cell interferons were active in this cell system also.

Animals↗
PubMed1979

Decrease of sensitivity to cell-growth inhibitory effect of interferon in human embryo cells after infection with SV40.

No changes in sensitivity of human embryo cells (HEC) to the antiviral action of interferon early (i.e. up to 17 days) after infection with simian virus 40 (SV40) could be detected. At the same time the sensitivity of cells to the cell-growth inhibitory effect of interferon decreased considerably. The changes in sensitivity of HEC to interferon action occurred during 5 successive passages following the infection with SV40 and remained on a similar level thereafter. During this period, no morphological alterations of cells were observed.

Cell Division↗
PubMed1979

The effect of native and sonicated double-stranded polyribonucleotides on the course of spontaneous autoimmune disease in NZB and NZB/Swiss F1 mice.

The administration of sonicated fractions of f2 phage polyribonucleotides caused an increased weight loss and deterioration of the clinical state in female NZB mice. Discontinuance of the treatment resulted in an improvement of both the clinical state and the genetically determined autoimmune disorders of these mice. Some potential explanations of this effect are discussed.

Animals↗
PubMed1978

Quantitative immunoelectrophoresis of human interferon. A new approach to characterization of interferon preparations.

The electroimmunoassay (quantitative "rocket" immunoelectrophoresis) method was adopted for analysis and characterization of interferon preparations. Ammonium sulphate-precipitated anti-interferon globulin also containing unknown antibodies against antigens that contaminate interferon preparations was used in the tests. By comparing the results of the electroimmunoassay of fractions obtained by polyacrylamide gel electrophoresis of human leukocyte interferon with the antiviral activity of the fractions, an excellent dissociation of molecules with interferon activity from the bulk of contaminating antigens was achieved. The method is extremely sensitive and requires very small volumes for assay.

Electrophoresis, Polyacrylamide Gel↗
PubMed1977

The cell-growth inhibitory effect of interferon. Studies of a resistant cell-subline.

Studies performed in the CSV subline of mouse L-cells suggest that activated endogenous and/or exogenous viral infection might be the factor that modifies the cell surface and, in consequence, the sensitivity of the cell to the cell-growth inhibitory action of interferon. In contrast with the parental L-cells, the CSV subline obtained by prolonged passage of L-cells in the presence of interferon shows an altered electron microscopic morphology, absence of C type particles and a decreased agglutinability with Concanavalin A. It is resistant to the cell-growth inhibitory effect of interferon but retains the sensitivity toward its antiviral effect. However, the sensitivity of the CSV subline toward the cell-growth inhibitory effect of interferon increased significantly after treatment with 5-iododexyuridine, infection with the Harvey strain of mouse sarcoma virus and/or prolonged passages in vitro. In this respect, the CSV subline resembles the primary mouse embryonic cells. Since sensitivity of CSV cells increased also after treatment with cyclic 3'-5' adenosine monophosphate and/or prostaglandin E2, it is possible that the cell-growth inhibitory effect of interferon is mediated through the "second messenger" system.

Animals↗