Dorian H. Coppenhaver

The Interferons: Mechanisms of Action and Clinical Applications

The interferons (IFN) are one of the bodys natural defensive responses to such foreign components as microbes, tumors, and antigens. The IFN response begins with the production of the IFN proteins (alpha, beta, and gamma), which then induce the antiviral, antimicrobial, antitumor, and immunomodulatory actions of IFN. Recent advances have led to Food and Drug Administration approval of five clinical indications for IFN. Interferon alfa is approved for hairy-cell leukemia, condyloma acuminatum, Kaposis sarcoma in the acquired immunodeficiency syndrome, and non-A, non-B (type C) viral hepatitis. Interferon gamma has properties distinctive from those of IFNs alpha and beta and is approved as an immunomodulatory treatment for chronic granulomatous disease. Promising clinical results with IFNs have also been reported for basal cell carcinoma, chronic myelogenous leukemia, cutaneous squamous cell carcinoma, early human immunodeficiency virus infection, hepatitis B, and laryngeal papillomatosis. Future clinical uses of IFNs may emphasize combination therapy with other cytokines, chemotherapy, radiation, surgery, hyperthermia, or hormones.

Differential expression and regulation of thyrotropin (TSH) in T cell lines

The immune systems production of and response to thyrotropin (TSH) suggests the existence of a hypothalamic-lymphoid-thyroid regulatory axis (HLT). To evaluate the possible roles of lymphocyte-derived TSH we characterized its structure and regulation of production. Using an in vitro system, we screened T cell lines for the production of TSH in response to thyrotropin-releasing hormone (TRH). We identified MOLT 4 T cells as producers of intact TSH based on TSH radioimmunoassay (RIA) displacement and de novo synthesized protein structure similar to pituitary TSH. Northern blot analysis using a cDNA probe to TSH beta showed the existence of an mRNA species similar in molecular size to pituitary mRNA of TSH beta. The MOLT 4-derived TSH is induced in a dose-dependent fashion by TRH and that induction is significantly inhibited by the thyroid hormone, triiodothyronine (T3). HUT 78 T cells express an mRNA species similar to TSH beta but do not express detectable protein suggesting a lack of translation of the mRNA species. The evidence suggests that the MOLT 4 T cells serve as an in vitro model for TSH production and may be used to study differential expression of the genes for TSH in the immune system. Elucidation of this in vitro system will provide information on mechanisms of regulation of an HLT axis that are unique to the immune system as well as pathways common to the immune and neuroendocrine systems.

Broad antiviral activity in tissues of crustaceans

Innate antiviral substances occur in vertebrates and may function as host defenses. Virus infections are common among invertebrates, but little is known about the ability of invertebrates to control viral infections. Pre-existing antiviral substances may be particularly important, since invertebrates lack the antiviral defense conferred by specific immunity. In our study, we found that tissue extracts of blue crab (Callinectes sapidus), shrimp (Penaeus setiferus), and crayfish (Procambarus clarkii) contained antiviral activities that inhibit a variety of DNA and RNA viruses, i.e. Sindbis virus (SB), vaccinia virus (VAC), vesicular stomatitis virus (VS), mengo virus (MENGO), banzi virus (BANZI) and poliomyelitis (POLIO). The concentration of inhibitory activity was relatively high, ranging from 102 to 216 U/g tissue for Sindbis virus, using the various tissue extracts. The other viruses were somewhat less sensitive to the inhibitor. The main antiviral activity in the inhibitor preparation from blue crab resided in an approximately 440 kDa fraction. It was inactivated significantly by lipid extraction, but not by proteinase K or glycosidases. The antiviral mechanism of the inhibitor from the blue crab was inhibition of virus attachment to eukaryotic cells, as evidenced by inhibitory activity at 4 degrees C. These studies are among the first to show the existence of broadly active antiviral activities in aquatic crustaceans. These antiviral substances may function as innate host defenses in these species that lack specific antibody immunity and, therefore, merit further study.

Lipoproteins account for part of the broad non-specific antiviral activity of human serum.

Several antiviral substances have been detected in human serum but few have been shown to possess broad antiviral activity. These broadly active antiviral molecules could be of significance as innate defense mechanisms. We have previously identified and characterized a broadly antiviral glycoprotein, UTI3, which accounts for 50 antiviral units/ml of human and mammalian sera. In addition there are reports of antiviral activity of human serum apolipoprotein A-1 (apo A-1), an important constituent of high density lipoprotein (HDL), against human immunodeficiency virus (HIV) and herpesvirus. Therefore we investigated (1) whether HDL is broadly antiviral, (2) how much of the broad antiviral activity of serum is due to HDL, and (3) the mechanism(s) of HDLs antiviral action. In this paper we report that (1) HDL does have broad antiviral activity, (2) HDL accounts for a modest but significant portion of the antiviral activity of serum, and (3) HDL acts by preventing virus penetration. Overall, HDL may be one of the broadly antiviral defences in the bloodstream.

Synergy of antiviral actions of TNF and IFN-γ: Evidence for a major role of TNF-induced IFN-β

Abstract Tumor necrosis factor (TNF) potentiates the antiviral activity of interferon-gamma (IFN-γ) directly and through induction of IFN-β in HEp-2 cells. Antibody to IFN-β inhibits a large component of the TNF and IFN-γ synergy and immunoreactive IFN-β can be detected in the supernatant fluids of TNF-treated HEp-2 cells. Furthermore, the kinetics of development of this synergy and its susceptibility to inhibition by antibody to IFN-β is demonstrated.

Post-translational heterogeneity of the human vitamin D-binding protein (group-specific component)

The vitamin D-binding protein in human serum (the group-specific component) is an alpha 2-globulin which is genetically polymorphic in all populations studied. Previous work (J. Svasti and B. H. Bowman (1978) J. Biol. Chem. 253, 5188-5194, and J. Svasti, A. Kurosky, A. Bennett, and B. H. Bowman (1979) Biochemistry 18, 1611-1617) has shown that the electrophoretic variations of the proteins controlled by two allelic genes, Gc1 and Gc2, are due to at least three amino acid substitutions between Gc1 and Gc2 (Svasti et al. (1979] and to heterogeneity in the Gc1 phenotype arising from carbohydrate dissimilarities. Gc1 migrates electrophoretically as two protein bands, while Gc2 migrates cathodally as a single band. This study demonstrates a post-translational glycosylation difference occurring in a single area of the Gc1 sequence which accounts for the heterogeneity observed previously. The glycosylation site, a threonine residue, appears to be in a sequence which differs between Gc1 and Gc2. The O-glycosidic bond, which is typical of mucins, is rare in plasma proteins. The cyanogen bromide fragment containing the galactosamine-containing carbohydrate in Gc1 was partially sequenced through 20 residues from the amino terminus. No detectable galactosamine could be found in the homologous cyanogen bromide fragment in Gc2. A new purification procedure for the vitamin D-binding protein in human plasma has been developed. Three chromatographic steps provide purified protein.

Serum concentrations of vitamin D-binding protein (Group-specific component) in cystic fibrosis

SummaryVitamin D-binding protein (DBP) concentrations were determined in the sera of 90 cystic fibrosis homozygotes, 57 obligate heterozygotes, and 46 normal controls. Very significantly lower mean concentrations were found in the sera of CF homozygotes compared with both heterozygotes and controls (P<0.01, Wilcoxon Rank Sums Test). Subdivision of the samples by Gc phenotype showed that this relationship held true both in the Gc1 and Gc2-1 phenotypes. The small sample size of the Gc2 genotype makes the significance levels of limited usefulness, but the pattern of variation of DBP levels among CF homozygotes, heterozygotes, and controls was consistent with that observed for the Gc1 and Gc2-1 classes. Haptoglobin levels showed high coefficients of variation when compared among CF homozygotes, obligate heterozygotes, and controls, presumably because of nonspecific elevation in the acute-phase response. Alpha2-macroglobulin levels were, if anything, slightly elevated in CF homozygotes compared with controls, while albumin levels showed no significant mean differences between these groups. Since the DBP concentration does not vary with age nor with levels of vitamin D and its metabolites, we interpret our results to mean that DBP levels are specifically decreased in cystic fibrosis, perhaps as the result of impaired glycosylation of the protein.

Innate antiviral defenses in body fluids and tissues.

Abstract Innate, non-specific, resistance mechanisms are important barriers to pathogens, particularly delaying virus multiplication at the onset of infections. These innate defense mechanisms include a series of mechanical barriers, pre-existing inhibitory molecules, and cellular responses with antimicrobial activity. The antiviral activities of these innate inhibitors reside in a variety of partly characterized substances. This review presents the innate antiviral inhibitors in cell cultures, urine, serum, the gastrointestinal tract, the nervous system, tissues of crustaceans, and saliva. Medical adaptation of the innate antiviral defense mechanisms may be useful for prevention and treatment of viral infections.

Arenavirus infection in the guinea pig model: Antiviral therapy with recombinant interferon-α, the immunomodulator CL246, 738 and ribavirin

Human arenaviral infections have a high mortality, and are dangerous to work with in the laboratory. There is a need for good antiviral agents to treat these infections. Pichinde virus infection of the inbred strain 13 guinea pig is a relatively safe, good animal model for human arenavirus infections. Mortality is consistently 100% between days 12 and 25 (mean 14.8) days after infection. When infected animals were treated with recombinant human interferon alpha A, or with CL246,783, an immunomodulator known to induce interferon, no beneficial effect was noted. When animals received ribavirin, 25 mg/kg/day for the first 14 days of infection, the course of infection was prolonged, with death occurring a mean of 22.5 days after infection. If ribavirin was administered for 28 days, mortality was reduced to 25%, with those animals dying a mean of 21.0 days after infection. These results confirm the studies that indicate that ribavirin is a useful agent for treating arenaviral infections. However, treatment with this agent must be prolonged. They also demonstrate the potential usefulness of Pichinde virus infection in strain 13 guinea pigs as an animal model of human disease.

Prosimian Hemoglobins I. The Primary Structure of the β-Globin Chain of Lemur Catta

The primary structure of the beta chain from the hemoglobin of a prosimian primate, Lemur catta, has been determined by automated Edman degradation of intact polypeptide chain and fragments produced by tryptic, cyanogen bromide and acid cleavage, and by homology with the sequence of Lemur fulvus. The sequence presented here differs from the human beta-globin sequence at 26 sites. This is the same degree of divergence previously reported for the beta-globin chain of Lemur fulvus. The sequences of the two congeneric lemuroid beta-globin chains are surprisingly divergent, differing at 18 sites. Of the 26 positions where L. catta differs from Homo sapiens, 7 are at positions with defined function. Of these 7 positions, 4 (2-Phe, 54-Ile, 94-Val, 112-Ile) are unique to L. catta among the primate beta-globin chains of established sequence. Residue 112-Ile is consistent with the prediction of Beard and Goodman (19) of an isoleucyl residue in this position in the ancestral primate beta-globin chain.