Spontaneous production of human interferon.

Pickering, L.; Kronenberg, Lee H.; Stewart, William E.

doi:10.1073/pnas.77.10.5938

Cited by 30 publications

(20 citation statements)

References 40 publications

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“…We did not observe significant protection of fibroblasts with Namalva cell medium, even when it was tested at a 1:1 dilution. This finding is in agreement with a recent report that Namalva cells cultured under conditions similar to those described here produce very little, if any, interferon (16).…”

Section: Resltltssupporting

confidence: 83%

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Elevated levels of (2'-5')oligoadenylic acid polymerase activity in growth-arrested human lymphoblastoid Namalva cells.

Krishnan¹,

Baglioni²

1981

Mol. Cell. Biol.

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(2'-5')Oligoadenylic acid [(2'-5')An] polymerase activity was measured in extracts of human lymphoblastoid cells of the Namalva line cultured under different conditions. Exponentially growing cells had a relatively low polymerase activity level, whereas cells grown to limit density showed elevated levels. When fresh medium was added to growth-arrested cells, (2'-5')An polymerase activity decreased concomitantly with the initiation of active deoxyribonucleic acid synthesis. An increase in polymerase activity level was also observed after exponentially growing cells were transferred from medium containing 20% serum to fresh medium containing 0.2% serum. These cells diminished deoxyribonucleic acid synthesis and remained quiescent until 20% serum was again added. Polymerase activity level decreased as the cells entered into S phase. The addition of the inhibitor of deoxyribonucleic acid synthesis, hydroxyurea, to exponentially growing cells did not increase polymerase level, indicating that cells blocked in S phase and at the G1-S boundary maintained the basal level of this enzyme. Degradation of labeled (2'-5')An was measured in extracts of Namalva cells cultured under different conditions, but no significant differences among degradative activities were observed. Since (2'-5')An polymerase activity is one of the enzymatic activities induced by interferon, we measured interferon titers in Namalva cell medium. Less than 1 reference unit per ml was detected in cells grown under different conditions. Moreover, the increase in (2'-5')An polymerase activity level in cells transferred from 20 to 0.2% serum was not prevented by including anti-lymphoblastoid interferon antibody in the medium. These results suggest that the activity level of (2'-5')An polymerase is regulated in Namalva cells on the basis of the growth status of the cells and that this regulatory mechanism is apparently not activated by interferon.

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Section: Resltltssupporting

confidence: 83%

“…It seems unlikely that this increase in polymerase activity is mediated by interferon, since we were unable to detect significant levels of interferon in the culture medium. Moreover, other lymphoblastoid cell lines investigated by Pickering et al (16) secrete interferon spontaneously only during exponential growth.…”

Section: Resltltsmentioning

confidence: 99%

Elevated levels of (2'-5')oligoadenylic acid polymerase activity in growth-arrested human lymphoblastoid Namalva cells.

Krishnan¹,

Baglioni²

1981

Mol. Cell. Biol.

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“…See Tables 1 and 2. LuKII cells were obtained from W. Stewart (14). B-cell lines transformed by Epstein-Barr virus were derived from patients with melanoma (15).…”

Section: Methodsmentioning

confidence: 99%

Human tumor necrosis factor produced by human B-cell lines: synergistic cytotoxic interaction with human interferon.

Williamson¹,

Carswell²,

Rubin³

et al. 1983

Proc. Natl. Acad. Sci. U.S.A.

378

143

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Human cell lines of hematopoietic origin were tested for production of tumor necrosis factor (TNF) hTNF activity was not found in supernatants of cell lines of T-cell, monocytic, or promyelocytic origin. Partially purified hTNF has a molecular weight of approximately 70,000, has no interferon activity, is acid labile, is destroyed by heating at 70°C for 1 hr, induces cross-resistance to mouse TNF in vitro, and causes hemorrhagic necrosis of Meth A mouse sarcoma in the standard in vivo mouse TNF assay. Tests with a panel of 23 human cancer cell lines showed that hTNF is cytotoxic for 7 cell lines, cytostatic for 5, and has no effect on 11. Comparative studies with human a, fi, and y interferons indicated that sensitivity to hTNF and interferon can be distinguished. Combined treatment with hTNF and a or y interferon resulted in a synergistic cytotoxic effect.

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“…Recently IFNs have been considered to also have a negative regulatory role in the autocrine regulation of cell proliferation, as several growth factors induce the formation ofIFN in the cells they stimulate (4)(5)(6). In addition, IFN-a and IFN-/3 are also constitutively expressed in cells derived from the hematopoietic system: in lymphoblastoid cells, in leukemic and normal peripheral leukocytes, and in macrophage cultures (7,8).…”

mentioning

confidence: 99%

Interferon alpha induces the expression of retinoblastoma gene product in human Burkitt lymphoma Daudi cells: role in growth regulation.

Kumar

Atlas

1992

Proc. Natl. Acad. Sci. U.S.A.

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Interferon a (IFN-a) is a regulatory secretory protein with distinctive biological effects such as antiproliferative actions against many tumor cell lines, including human Burkitt lymphoma Daudi cells. The mechanism underlying growth inhibition by IFN-a is not well established. The growth of many mammalian cell types is also regulated by tumor suppressor retinoblastoma (RB) gene product, the RB protein.In the studies presented here, we explored the possible involvement of RB protein in the growth inhibitory action of IFN-a in the Daudi cell model system. We observed that IFN-a induces a 3-to 10-fold increased expression of RB protein in growth-

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Spontaneous production of human interferon.

Cited by 30 publications

References 40 publications

Elevated levels of (2'-5')oligoadenylic acid polymerase activity in growth-arrested human lymphoblastoid Namalva cells.

Elevated levels of (2'-5')oligoadenylic acid polymerase activity in growth-arrested human lymphoblastoid Namalva cells.

Human tumor necrosis factor produced by human B-cell lines: synergistic cytotoxic interaction with human interferon.

Interferon alpha induces the expression of retinoblastoma gene product in human Burkitt lymphoma Daudi cells: role in growth regulation.

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