Ladislav Borecký

Immunodominant structures in the aminoterminal portion of human interferon α 1

Abstract The analysis of the antigenic structure of human interferon (IFN)-α 1 with a panel of monoclonal antibodies revealed four immunodominant regions. Three of them, recognized by 12 of 14 antibodies were mapped into the aminoterminal portion of IFN-α 1 around residues 31–38, 43–53 and 63–85. The region 31–85 proved important also for the antiviral and antiproliferative activity of the IFN-α 1 molecule. The antibody recognizing the sequence around residues (54)63–67 also inhibited the cellular binding of IFN-α 1 to the high-affinity receptors.

Electrophoretic Profiles and Activities of Human Interferon in Heterologous Cells

Human leukocyte interferon (IF) was found active in homologous human and heterologous rodent cells both in antiviral tests and in tests measuring cell-growth inhibitory activity. About 10 times more u

Peptide-mapping of three neutralizing epitopes into predicted biologically active sites of human interferon-α2

Immunologically less reactive but functionally relevant structures were identified on human interferon (IFN)-alpha 2 by three neutralizing monoclonal antibodies (mAb). The binding sites of these mAbs were mapped using a set of synthetic peptides that covered the amino acid sequence of two predicted biologically active segments in the regions 31-53 and 63-85 of IFN-alpha 2. We measured the capacity of fragments to inhibit the IFN-neutralizing activity of mAbs and located three linear epitopes around residues 42-53, 63-76 and 77-85 of the IFN-alpha 2 molecule.

Are the acid-labile interferon α and interferon ω-1 identical?

The interferon (IFN) activity found in human leukocyte IFN alpha preparations, autoimmune and AIDS sera, and others was reported to have distinct antigenic and deviating biological properties. This led to its vague designation as acid-labile and thermolabile IFN alpha. However, using specific monoclonal antibodies, the acid-labile component of IFN alpha (not exposed to pH 2) and recombinant IFN omega 1 showed significant relatedness. Monoclonal antibody T19, generated with virus-induced leukocyte IFN alpha that had not been exposed to pH 2, neutralized both the antiviral and antiproliferative activities of IFN omega-1, and vice versa; monoclonal antibody OMG 5, specific for recombinant IFN omega-1, cross-neutralized the antiviral and antiproliferative effects of the acid-labile component of leukocyte IFN alpha. When these two IFN preparations were incubated at pH 2 for 72 hr, their biological activity significantly decreased.

Human acid- and thermolabile α-interferon-like substance: Selective reactivity with a monoclonal antibody

An acid- and thermolabile alpha-interferon-like substance, designated AL-IFN-alpha, has been found in non-processed normal human leukocyte IFN preparations as well as sera from patients with autoimmune or other chronic diseases. Little is known about origin, production and biological activity of these IFN activities. Monoclonal antibodies were obtained which proved highly selective in neutralizing AL-IFN-alpha in both anti-proliferative and antiviral tests. While the monoclonal antibodies were strict specific, polyclonal antibodies against various interferons showed less specificity in these tests. The results suggest that AL-IFN-alpha represents an antigenically distinct IFN-alpha subtype or, alternatively, a new lymphokine with antiproliferative and antiviral activity.

THE CELL GROWTH INHIBITORY AND ANTIVIRAL EFFECTS OF INTERFERON IN CLONED TRANSFORMED MOUSE CELLS

Eight clones and two subclones of SV40- and seven clones and one subclone of 20-methylcholanthrene-transformed C3H mouse embryonic fibroblasts were compared in tests for sensitivity to the antiviral and cell-growth inhibitory activities of a partially purified mouse L-cell interferon. While the sensitivity of clones and subclones to the antiviral activity of interferon was comparable to that of parent lines, the cell-growth inhibitory activity of interferon in the SV40 clones showed more than 100-fold variation and the methylcholanthrene-transformed cells could be divided into two groups in this respect. No correlation of sensitivity to the cell-growth inhibitory effect of interferon with the chromosome number, interferon-producing capacity or tumorigenicity of the clones could be detected. However, the cells of the interferon-sensitive clones No. 36 of the methylcholanthrene-transformed line were destroyed by macrophages at higher percentage binding of 125I-labeled soybean lectin. These results suggest that (1) the cell-growth inhibitory effect of interferon might be mediated by a specific type of receptors, and (2) N-acetyl-galactosamine present on the surface of interferon-resistant cells in a higher concentration than on interferon-sensitive cells hinders the recognition of cells both by macrophages and by interferon.

Porcine leukocyte interferon exhibits close antigenic relatedness to human interferon alpha 2, but not to human interferon alpha 1

As reported by others using polyclonal antisera, natural human and porcine interferons (IFN)-alpha are antigenically related. Using monoclonal antibodies (mAb) in neutralization and ELISA experiments, we found differences in the subtype/antigenic composition between virus-induced porcine and human leukocyte preparations. Human leukocyte IFN-alpha contains two major antigenically distinct subtypes, IFN-alpha 1 and IFN-alpha 2. However, swine leukocytes produced only a single predominant species of IFN-alpha with high antigenic homology to human IFN-alpha 2. Moreover, we were unable to detect close antigenic relatedness between recombinant porcine and human IFN-alpha 1 subtypes.

Preparation of highly sensitive mouse hybrid cells for interferon assays

In this letter we show that the sensitivity of L-929 cells to IFN can be markedly enhanced using somatic cell hybrids in the test. After fusion of mouse L-929 (HGPRT − ) cells with peritoneal macrophages from Swiss mice in HAT selection system, three clones of adherently growing hybrid cells were isolated. Subsequently, the sensitivity of hybrid cells to the antiviral activity of IFN was compared with the parental cells. IFN titers were determined by a 50% endpoint cytopathic effect assay using parental and/or hybrid cells challenged with vesicular stomatitis virus