Synthesis of 2'5'-oligo(A) in extracts of interferon-treated HeLa cells.

Natural killer (NK) cells in the human are a population of large granular lymphocytes (LGL) with at least one unique surface antigen not expressed on cells of other lineages. NK-target-cell interaction appears to involve carbohydrate recognition and, following binding, the NK cells are induced to generate O2−, transmethylate membrane phospholipids, and activate phospholipase A2. Some or all of these activities trigger a cascade of events which ultimately leads to the secretion of a substance toxic to the target cell. A variety of genes controls various steps in this cytolytic pathway. There is a good deal of evidence in the mouse, and some in the human, that NK cells play a role in host surveillance against tumor development, resistance to viral infections, and, possibly, hematopoietic regulation.

The biology of the human natural killer cell

Gangliosides inhibit 125I-labeled thyrotropin binding to the thyrotropin receptors on bovine thyroid plas- ma membranes, on guinea pig retro-orbital tissue plasma membranes, and on human adipocyte membranes. This inhi- bition by gangliosides is critically altered by the number and location of the sialic acid residues within the ganglioside structure, the efficacy of inhibition having the following order: GDlb > GT1 > GM1 > GM2 = GM3 > GDla The inhibi- tion results from the interaction of thyrotropin and ganglios- ides, rather than the interaction of membrane and ganglios- ides. Fluorescence studies show that the inhibition is associ- ated with a distinct conformational change of the thyrotro- pin molecule and that the progression from a "noninhibitory conformation" to an "inhibitory conformation" arallels ex- actly the order of effectiveness in inhibiting 125I-Yabeled thy- rotropin binding. The ganglioside inhibition of 125I-labeled thyrotropin binding appears to be hormonally specific in that it is not affected by albumin, glucagon, insulin, prolactin, fol- licle-stimulating hormone, growth hormone, or corticotropin. The possibility that a ganglioside or ganglioside-like struc- ture is a component of the thyrotropin receptor is suggested by the finding that gangliosides more complex than N-acetyl- neuraminylgalactosylglucosylceramide are present in bovine thyroid membranes in much higher quantities than have been previously found in extraneural tissue. The finding that the B component of cholera toxin, which also interacts with gangliosides, has a peptide sequence in common with the : subunit of thyrotropin, suggests that thyrotropin and cholera toxin may be analogous in their mode of action on the mem- brane.

Thyrotropin-ganglioside interactions and their relationship to the structure and function of thyrotropin receptors (hormone mechanism/cholera toxin/luteinizing hormone/human chorionic gonadotropin/adenylate cyclase)

Anticellular and antiviral effects of pppA(2'p5'A)n.

Interferons (IFN) have been shown to suppress the proliferation of human erythroid progenitors (erythroid burst-forming units [BFU-E] and colony-forming units [CFU-E]) in vitro. To examine the mechanism(s) underlying this inhibitory activity, the effect of different doses (50-10,000 U) of a highly purified preparation of recombinant DNA produced human gamma-IFN on erythroid colony formation by normal human bone marrow BFU-E and CFU-E in the presence and absence of monocytes and/or T lymphocytes was studied. The addition of gamma-IFN to whole marrow caused suppression of BFU-E (6-65%) and CFU-E (31-79%) in a dose-dependent fashion. This inhibition occurred both with the direct addition of gamma-IFN to the culture plates as well as by the preincubation of marrow cells with gamma-IFN followed by the washing of the cells; at the highest concentration of gamma-IFN (10,000 U), near-maximal inhibition of colony formation occurred with as little as 15 min of preexposure (BFU-E, 50%; CFU-E, 81%). Removal of monocytes and/or T lymphocytes before the addition of gamma-IFN significantly reduced the inhibitory effects of this lymphokine (BFU-E, -1 to 38%; CFU-E, -8 to 67%). Co-culture of purified autologous monocytes or T cells preexposed to gamma-IFN with monocyte and T cell-depleted marrow cells resulted in highly significant inhibition of erythroid colony formation even when these treated cells comprised less than 1% of the total nucleated cell populations in culture. The inhibitory action of gamma-IFN was not prevented or reversed by erythropoietin. These results demonstrate that the inhibitory effects of gamma-IFN on erythropoiesis are mediated to a significant degree through accessory cell populations, and suggest that gamma-IFN may represent a useful tool in the study of the role of immunocompetent cells in the regulation of erythropoiesis in vitro.

/pdf/suppression-of-normal-human-erythropoiesis-by-gamma-3d37tykvgd.pdf

Suppression of normal human erythropoiesis by gamma interferon in vitro. Role of monocytes and T lymphocytes.

INTRODUCTION.............................................................. 543 ESTABLISHMENT OF THE ANTIVIRAL STATE ........... .................... 544 Interferon Binding ................... ............................. 544 Development of Antiviral Activity................................. 546 LOCUS OF THE INTERFERON-INDUCED INHIBITION OF VIRUS GROWTH. . 547 Evidence that Interferon Treatment Inhibits Virus Uncoating ....... ........... 547 Evidence that Interferon Treatment Inhibits Transcription of the Viral Genome. 547 Evidence that Interferon Treatment Inhibits Viral Protein Synthesis ..... ...... 550 Observations in virus-infected cells ........................... 551 Observations in cell-free systems ....... .................... 552 Evidence that Interferon Treatment Inhibits Terminal Events in the Replication Cycle of Murine Leukemia Viruses ........ ................. 557 INTERFERON TREATMENT IS INEFFECTIVE IN SYSTEMS IN WHICH THE SV40 GENOME IS INTEGRATED INTO AN INTERFERON-RESISTANT VIRUS OR A HOST GENOME ........................... 559 DISCUSSION ............................. 560 LITERATURE CITED........................... 562

https://mmbr.asm.org/content/mmbr/41/3/543.full.pdf

Antiviral activity of interferons.

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Antiviral activity of interferons.