Induction of gamma-interferon activity by elevated temperatures in human B-lymphoblastoid cell lines

Local hyperthermia could induce antiviral activity by endogenous interferon-dependent pathway in condyloma acuminata

Local hyperthermia has been successfully used in the treatment of viral warts by mechanisms that have largely remained unclear. Using an organotypic culture system, we found that hyperthermia at 42 °C and 45 °C could induce a significant increase in the transcriptional expression of interferon (IFN)-α, IFN-β and IFN-γ, in a temperature-dependent manner in condyloma acuminata (CA), but not in normal skin. Accordingly, local hyperthermia could enhance the expression of 2'-5' oligoadenylate synthase and double-stranded RNA (dsRNA)-dependent protein kinase, two antiviral enzymes downstream of the IFN-dependant pathway. Hyperthermia led to an increase in IFN-α/β receptor transcripts, and an increase in the levels in phospho-Stat1 and phospho-Stat2 in CA, though it had no influence on the levels of Jak1, Tyk2, Stat1 and Stat2 transcriptional expression. Local hyperthermia was proved effective in treating human papillomavirus-infected skin. These results suggested that hyperthermia took effect partly by inducing the expression of local endogenous IFN and partly by subsequent IFN-induced antiviral activity via Jak-STATs signalling pathway in CA.

Interferon gamma upregulates its own gene expression in mouse peritoneal macrophages

Interferon gamma (IFN-gamma) exerts a variety of immunoregulatory effects on several cell targets. It is generally assumed that IFN-gamma is specifically produced by T and large granular lymphocytes. In this study, we show that IFN-gamma is constitutively expressed in resting mouse peritoneal macrophages (PM). Treatment of PM with cycloheximide results in a significant accumulation of IFN-gamma mRNA, suggesting that a short-lived IFN-gamma mRNA accumulates when protein synthesis is inhibited. Moreover, treatment of PM with IFN-gamma also results in a clear-cut accumulation of this mRNA. This effect is not observed in murine lymphocytes from mesenteric lymph nodes (which instead produce IFN-gamma after phytohemagglutinin treatment) and in mouse cell lines. The treatment of PM with IFN-gamma also results in secretion of IFN-gamma after 24-48 h. The upregulation of IFN-gamma expression is also found in PM from anti-asialo GM1-treated nude mice. We suggest that the ability of PM to produce this IFN-gamma is indicative of an autocrine mechanism. The macrophage IFN-gamma may play a role in the regulation of cell differentiation and immune response.

Alcohols induce interferon in primary chick embryo cells

Primary chick embryo cells (CEC), cultured in vitro, produce interferon (IFN) following alcohol treatment. Brief exposure of cells to methanol, ethanol, 2-propanol, or butanol resulted in the production of an acid-labile IFN which could be detected in the supernatant medium as early as 60 min after removal of the drug. Following "priming" of the cells by homologous IFN, these four alcohols induced even greater yields of IFN: up to 4,000 units per 10(7) cells of an acid-stable IFN were detected. In contrast, priming of CEC with IFN had no effect on the yield of IFN induced by a standard viral inducer, avian reovirus. Maximal IFN production by ethanol in IFN-primed cells depended on both the priming dose of IFN and length of contact with the cells, as well as the in vitro age of the cell cultures. Complete neutralization by polyclonal anti-chick IFN serum, of both the acid-labile and acid-stable preparations induced by ethanol treatment confirmed that both were chicken IFNs. This report describes the general characteristics of IFN induction in primary chick embryo cells by alcohols, with particular emphasis on ethanol, chemically the simplest IFN inducer reported to date.

Thermotolerance of isolated mitochondria associated with heat shock proteins

Mitochondria isolated from 2-day-old etiolated soybean (Glycine max) seedlings which had been subjected to various heat shock treatments, i.e. (A) 28 degrees C (2 h), (B) 38 degrees C (2 h), (C) 38 degrees C (2 h)-42.5 degrees C (0.5 h), and (D) 38 degrees C (2 h)-42.5 degrees C (0.5 h)-28 degrees C (4 h), were monitored for O(2) uptake using an oxygen electrode. Mitochondria isolated after all four heat shock treatments were active in O(2) consumption at 28 degrees C in response to succinate and ADP (derived P/O ratios were 1.6, 1.7, 1.3, and 1.3, respectively.) The mitochondria from all four treatments were also active in O(2) uptake at 42.5 degrees C. However, only mitochondria isolated after treatment (C) were tightly coupling at 42.5 degrees C (derived ADP/O ratio was about 1.4). Combined with our earlier findings on the subcellular localization of heat shock proteins, our present data demonstrate that association of heat shock proteins with mitochondria by treatment (C) enables them to phosphorylate at 42.5 degrees C (i.e. they become thermotolerant). Isolated mitochondria from treatment (C) and treatment (A) were compared by electron microscopy. They appeared to be very similar and no significant ultrastructural differences were noted.

Activation of NK cells in subjects exposed to mild hyper- or hypothermic load

The effect of mild hyper- and hypothermic stress on release of selected hormones (somatotropin, noradrenaline, etc.), interferon (IFN), and activity of NK cells in the blood was examined in groups of young males during a 30 min exposure to 39 degrees C and 4 degrees C. A quick release of somatotropin was registered in 44% of examinees in the hyperthermic group, while the persons exposed to 4 degrees C reacted with a release of noradrenaline only. Concurrently, an elevation of NK cell activity was observed both in the subgroup releasing somatotropin after hyperthermic stress and in the group exposed to cold. Since these forms of mild stress did not lead to an appearance of IFN in the serum, the possibility of an NK cell activating effect of somatotropin and/or the adrenal hormones was tested. While the adrenal hormones stimulated the NK cell activity in vitro, no support for a similar role for somatotropin was found.

Specific inhibition of simian virus 40 protein synthesis by heat and arsenite treatment

The effects of heat treatment of CV1 cells infected with simian virus 40 (SV40) on viral and cellular protein synthesis were investigated by one-dimensional and two-dimensional polyacrylamide gel electrophoresis. A 12-h heat treatment during the late phase of the viral life-cycle inhibits VP1 synthesis. No inhibition of normal cellular proteins is apparent, but heat-shock proteins are strongly induced and accumulate in the cells. Inhibition of VP1 synthesis in infected cells is demonstrated to occur also after arsenite treatment, another agent known to induce heat-shock proteins. Northern blot analysis of cytoplasmic RNA demonstrated a decrease in the abundance of late SV40 mRNAs thus showing that the inhibition occurs at the transcriptional or immediately post-transcriptional level. Cumulative labeling with [3H]thymidine of viral DNA showed that the decrease in the abundance of late mRNAs is not due to a blocking of viral DNA synthesis. Immunofluorescence microscopy and immunoprecipitation analysis show that heat and arsenite treatments also affect the synthesis of T antigen. These results suggest that heat-shock proteins may play a role in the inhibition of SV40 virus gene functions.

In vivo hyperthermia enhances plasma antiviral activity and stimulates peripheral lymphocytes for increased synthesis of interferon-gamma

The effect of in vivo hyperthermia on plasma interferon (IFN) activity and on the induction of IFN-gamma by phytohemagglutinin (PHA) or staphylococcal enterotoxin B (SEB) in isolated leukocyte cultures was investigated. Adult rhesus monkeys (Macaca mulatta) were placed in a climatic chamber maintained at 45 degrees C until their core body temperatures increased 2 degrees C above control levels. Peripheral blood samples were withdrawn both prior to core temperature elevation and at the time of peak body temperature. Plasma IFN-alpha increased slightly from a control value of 12 U/ml to 16 U/ml at the elevated core temperature. However, this alteration of plasma IFN levels appears to be a complex process that includes the loss of certain circulating IFN-alpha subtypes and the influx of acid-labile (Type II) IFN-alpha. Additionally, a non-IFN antiviral factor present in the plasma was elevated 10-fold at the higher body temperature. When mononuclear cells were isolated and cultured at 37 degrees C in the presence of PHA or SEB, those cells isolated from animals at the peak of body temperature showed a 4- to 16-fold increase in IFN-gamma activity relative to cells isolated from the same animal before the temperature increase. Similar results were obtained with cells isolated when fever was induced by the systemic injection of nonviable Escherichia coli. These results demonstrate that increased body temperature results in a circulating lymphocyte pool which is "primed" for the production of elevated levels of IFN-gamma activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Interferon pretreatment lowers the threshold for maximal heat-shock response in mouse cells

Interferons (IFNs) are proteins which have antiviral and antiproliferative properties and are known to affect various immunological processes. Some of these activities have been shown to be potentiated by increased temperatures. When cells are subjected to a rise in temperature, the synthesis of the heat-shock proteins (HSPs) is 'switched on.' In this report we demonstrate a synergistic effect of IFN and stress (arsenite treatment or elevated temperature) on the heat-shock response. On the one hand, IFN pretreatment enhances the accumulation of HSP mRNAs and the corresponding protein synthesis after a mild stress and, on the other hand, it amplifies the decrease of the total protein synthesis after a severe stress. Thus in IFN pretreated cells the range of temperatures leading to the heat-shock response is shifted towards common physiological values.

Burkitt's cells can be triggered by teleocidin to secrete interferon-gamma

The secretion of interferon (IFN)-gamma by T lymphocytes is mediated by the synthesis of interleukin 2 (IL-2) and the availability of IL-2 receptors. Since some Burkitt's lymphoma lines express Tac antigen and can be triggered to secrete IL-2 following activation with the new tumor promoter teleocidin, we addressed the question of whether the induction of IL-2 by B lymphocytes is accompanied by the induction of IFN-gamma. IFN-gamma has not been detected in any of the 25 cell lines studied, and following stimulation with teleocidin, we triggered the synthesis of IFN-gamma in JLP(C), a pre-Burkitt's cell line. The mechanism of IFN-gamma secretion by B lymphocytes is not clear. Our findings demonstrate that the synthesis of IL-2 by B cells is not accompanied by IFN-gamma and suggest that the synthesis of IFN-gamma is not mediated by IL-2 or IL-1 or B-cell growth factor. Neutralization studies have shown that IFN-gamma secretion is not accompanied by the induction of IFN-alpha or IFN-beta. Our data imply that B cells can be triggered to secrete IFN-gamma under certain circumstances. Whether similar function occurs in vivo is not known.