Variation of (2'-5') oligo A synthetase level in lymphocytes and granulocytes of patients with viral infections and leukemia

Myalgic encephalomyelitis, chronic fatigue syndrome: An infectious disease

The etiology of myalgic encephalomyelitis also known as chronic fatigue syndrome or ME/CFS has not been established. Controversies exist over whether it is an organic disease or a psychological disorder and even the existence of ME/CFS as a disease entity is sometimes denied. Suggested causal hypotheses have included psychosomatic disorders, infectious agents, immune dysfunctions, autoimmunity, metabolic disturbances, toxins and inherited genetic factors. Clinical, immunological and epidemiological evidence supports the hypothesis that: ME/CFS is an infectious disease; the causal pathogen persists in patients; the pathogen can be transmitted by casual contact; host factors determine susceptibility to the illness; and there is a population of healthy carriers, who may be able to shed the pathogen. ME/CFS is endemic globally as sporadic cases and occasional cluster outbreaks (epidemics). Cluster outbreaks imply an infectious agent. An abrupt flu-like onset resembling an infectious illness occurs in outbreak patients and many sporadic patients. Immune responses in sporadic patients resemble immune responses in other infectious diseases. Contagion is shown by finding secondary cases in outbreaks, and suggested by a higher prevalence of ME/CFS in sporadic patients' genetically unrelated close contacts (spouses/partners) than the community. Abortive cases, sub-clinical cases, and carrier state individuals were found in outbreaks. The chronic phase of ME/CFS does not appear to be particularly infective. Some healthy patient-contacts show immune responses similar to patients' immune responses, suggesting exposure to the same antigen (a pathogen). The chronicity of symptoms and of immune system changes and the occurrence of secondary cases suggest persistence of a causal pathogen. Risk factors which predispose to developing ME/CFS are: a close family member with ME/CFS; inherited genetic factors; female gender; age; rest/activity; previous exposure to stress or toxins; various infectious diseases preceding the onset of ME/CFS; and occupational exposure of health care professionals. The hypothesis implies that ME/CFS patients should not donate blood or tissue and usual precautions should be taken when handling patients' blood and tissue. No known pathogen has been shown to cause ME/CFS. Confirmation of the hypothesis requires identification of a causal pathogen. Research should focus on a search for unknown and known pathogens. Finding a causal pathogen could assist with diagnosis; help find a biomarker; enable the development of anti-microbial treatments; suggest preventive measures; explain pathophysiological findings; and reassure patients about the validity of their symptoms.

The MxA protein levels in whole blood lysates of patients with various viral infections

Interferon alpha (IFNalpha), a type I interferon, can be considered as a viral infection marker because this cytokine is induced during many viral infections. However, it is quite difficult to detect IFNalpha in sera. Investigations are interested in various intra-cellular IFNalpha-induced proteins as viral infection markers. However the activity of these enzymes increased not only in response to type I IFNs but also to type II IFN. MxA protein can be detected in the cytoplasm of IFNalpha/beta-treated cells, whereas other cytokines, including IFNgamma, are poor inducers. Using an immunochemiluminescent assay, we studied MxA protein in whole blood of 34 patients with various viral infections. The whole blood was drawn into sterile vacuum tubes containing heparin or EDTA. MxA values were relatively similar in heparin-treated samples and EDTA-treated samples, with differences not exceeding 1 ng/ml. The levels of MxA protein were compared in whole blood obtained by using two different lysis procedures. A correlation was found between the MxA levels obtained by using procedure I and procedure II, but higher amounts of MxA protein were found with procedure II. The second procedure is rapid and more convenient than the other and it is carried out in one step which reduce technical problems. High levels of MxA protein were found in peripheral blood cells of patients with acute viral infections (Rotavirus, Adenovirus, RSV, CMV), but MxA protein was not elevated in bacterial infections. The MxA levels were also studied in peripheral blood of 32 HCV positive patients. MxA protein was not found in most of IFNalpha-untreated patients, even those with high viral load. In contrast, high levels of MxA protein were found in IFNalpha-treated patients. MxA quantitation can be considered as a specific marker of acute viral infections, and could be useful in the management of treatment with IFNalpha.

Effect of alpha interferon (IFN-alpha) on 2'-5' oligoadenylate synthetase activity in peripheral blood mononuclear cells of patients with chronic hepatitis C: relationship to the antiviral effect of IFN-alpha

Alpha interferon (IFN-alpha) is, to date, the only treatment with proven efficacy in patients with chronic hepatitis C. However, less than 15% of the patients have a sustained response to IFN-alpha. Interferon acts through the induction of various cellular enzymes. Among them, the 2'-5' oligoadenylate synthetase (2-5OAS) is (at least in part) responsible for a direct antiviral effect of IFN-alpha. The aim of this study was to determine whether basal and IFN-alpha-induced in vivo and in vitro 2-5OAS activities measured in peripheral blood mononuclear cells predict biochemical and virological responses to IFN-alpha in patients with chronic hepatitis C. 2-5OAS activity in peripheral blood mononuclear cells and the antiviral effect of IFN-alpha were studied in 36 patients with chronic hepatitis C (27 men and 9 women; mean age, 44.7 years). Basal in vivo 2-5OAS activity (mean +/- standard error of the mean) was 4.41 +/- 0.69 nmol/10(6) cells. It was significantly induced at month 3 of IFN-alpha therapy (18.07 +/- 2.74 nmol/10(6) cells; P = 0.0001). No significant differences were found in basal in vivo 2-5OAS activities, in IFN-alpha-induced/basal in vitro 2-5OAS activity ratios, in IFN-alpha-induced in vivo 2-5OAS activities, and in IFN-alpha-induced/basal in vivo 2-5OAS activity ratios between the patients with and without a biochemical response (normal alanine aminotransferase activity in serum) or a virological response (normal alanine aminotransferase activity in serum and negative hepatitis C virus RNA detection) at any step of the study. At month 3 of therapy, p69, which is considered to be the active isoform of 2-5OAS, was induced, as demonstrated by Western blot (immunoblot) analysis in 50% of the patients, and induction of the p100 isoform was observed in 70% of the patients. No significant relationship with the response to IFN-alpha therapy was observed. Our results suggest that a deficiency of the IFN-alpha-dependent 2-5OAS system, which could be genetically determined, is unlikely to be responsible for the failure to achieve biochemical and virological responses to IFN-alpha therapy in patients with chronic hepatitis C.

Lymphocytic 2',5'-oligoadenylate synthetase activity increases prior to the appearance of neutralizing antibodies and immunoglobulin M and immunoglobulin G antibodies after primary and secondary immunization with yellow fever vaccine

Primary and secondary immunizations with live, attenuated yellow fever virus vaccine (17D strain) were performed in order to study the course of appearance of virus-neutralizing antibodies and immunoglobulin M (IgM) and IgG antibodies directed against the virus and the interferon-dependent enzyme 2',5'-oligoadenylate synthetase (2',5'AS) activity, determined in homogenates of peripheral B and T lymphocytes. From cellular ATP, this enzyme generates 2',5'-oligoadenylates which mediate degradation of viral mRNA by stimulation of a latent RNase. By day 4 after the first immunization, the earliest and highest 2',5'AS activity was present in the T-lymphocyte fraction. By day 7, the enzyme activity was highest in the B-lymphocyte fraction. Virus-neutralizing antibodies appeared on day 7, and IgM antibodies were present on day 12. After the second immunization, performed 2 years +/- 2 months later, the only significant increase in 2',5'AS activity was observed in the T-lymphocyte fraction. Virus-neutralizing antibodies were present from day 1, whereas no IgM antibodies were detected. By day 12, 80% of the vaccines were IgG positive. In the primary and secondary (memory) immune responses, 2',5'AS activity is expressed in the T-lymphocyte fraction prior to the appearance of antibodies directed against the virus and may serve as an early and sensitive marker of an ongoing virus infection which is otherwise difficult to detect. No change in conventional laboratory analysis parameters, such as in differential blood cell counts or total IgA, IgG, and IgM, disclosed the immune activity in either the primary or the secondary immunization.

Hormonal and immunological regulation of 2', 5'-oligoadenylate synthetase activity in human peripheral blood mononuclear cells

A newly developed method for assaying 2', 5'-oligoadenylate (2, 5A) synthetase activity by polyacrylamide gel electrophoresis was applied to peripheral blood mononuclear cells (PBMC) from normal subjects, HIV-positive subjects, and renal cell carcinoma (RCC) patients. Sex differences were observed in 2, 5A synthetase activity of PBMC from normal young adults, males having eightfold higher activities of this enzyme than females. Moreover, compared to values for postmenopausal (PM) females receiving estrogen replacement, untreated PM females had higher activities. Collectively, these results suggest that estrogen downregulates 2, 5A synthetase activity. Activities of 2, 5A synthetase were investigated in two disease states associated with altered immune function. In one patient with AIDS-related Kaposi's sarcoma, interferon-alpha (IFN-alpha) therapy increased 2, 5A synthetase activity twofold. In addition, combined therapy with interleukin-2 (IL-2) and IFN-alpha increased 2, 5A synthetase activities in eight of nine patients with RCC. Therefore, in patients receiving immunotherapy with IL-2 and IFN-alpha, our new assay could contribute to evaluation of immune stimulation. In general, studies in vitro confirmed these observations; however, exposure of PBMC from RCC patients revealed that in vitro IL-2 failed to induce this enzyme activity as it did in PBMC from normal volunteers.

Interferon-induced and double-stranded RNA-activated enzymes: a specific protein kinase and 2',5'-oligoadenylate synthetases

Treatment of cells with interferon (IFN) results in the induction of two double-stranded RNA (dsRNA)-activated enzymes: a specific protein kinase and 2'-5' linked oligoadenylate [pppA(2'p5'A)n referred to as 2-5A] synthetases. The protein kinase, when activated by dsRNA, becomes autophosphorylated and catalyzes and phosphorylation of the protein synthesis initiation factor, eIF2. The 2-5A synthetases, when activated by dsRNA, form 2-5A molecules capable of activating a latent endoribonuclease that degrades RNA. By inhibiting initiation of protein synthesis or by degrading of RNA, these enzymes play key roles in two independent pathways that regulate overall protein synthesis.

Basal and interferon-induced 2',5'-oligoadenylate synthetase in human monocytes, lymphocytes, and peritoneal macrophages

2',5'-Oligoadenylate (2-5A) synthetase is an intracellular enzyme induced during viral diseases and after clinical administration of interferons (IFN). Because monocytes and T and B lymphocytes in peripheral blood are targets of viral infection, we compared the basal levels and induction of 2-5A synthetase activity in these three cell types. IFN-beta induced significant, three- to eightfold increases in 2-5A synthetase activity in monocytes and T and B lymphocytes, both in vitro and in vivo. IFN-gamma was less effective in inducing 2-5A synthetase than IFN-beta, yielding up to 2.6-fold increases in monocytes and slight increases in lymphocytes in vitro. IFN-beta also had greater 2-5A synthetase-inducing activity than IFN-gamma in HL-60 and U937 monocytic cell lines and in human peritoneal macrophages. Baseline levels of 2-5A synthetase in untreated peripheral blood monocytes separated by adherence or density gradients were three- to fivefold higher than in lymphocytes. 2-5A synthetase levels were twofold higher in B than in T lymphocytes separated by fluorescence-activated cell sorting. Tumor necrosis factor-alpha (TNF-alpha) did not induce this enzyme in peripheral blood mononuclear cells (PBMCs) or peritoneal macrophages. Thus, monocytes had greater basal and induced levels of 2-5A synthetase activity than did lymphocytes and contributed disproportionately to total 2-5A synthetase activity in peripheral blood.

Enzyme immunoassay of 2'-5'-oligoadenylates at the femtomole level

We have developed a competition enzyme immunoassay (EIA) for 2'-5'-oligoadenylates [p kappa(A2'p5')nA; 0 less than or equal to kappa less than or equal to 3; 1 less than or equal to n] based on an anti-A2'p5' A monoclonal antibody coated onto 96-well polystyrene plates and A2'p5' A peroxidase as a marker. It permits measurement of 5'OH(A2'p5')nA as such and p kappa(A2'p5')nA after alkaline phosphatase hydrolysis, with a detection threshold of 5 X 10(-12) M. All 2'-5'-oligomers were assayed with similar sensitivity. ATP and adenosine did not interfere at concentrations up to 10(6)-fold higher than those of 2'-5'-oligoadenylates. Reproducibility, stability of reagents and correlation with the radioimmunoassay were good. As such, this EIA is a suitable tool for studying the 2-5A system, particularly, in clinical investigations: the initial velocity of 2-5A synthetase can be determined on 10,000 cells without purification and the level of 2'-5'-oligoadenylates can be assayed on less than 1 ml of blood.

Relationship of HLA protein display to activation of 2-5A synthetase in HBe antigen or anti-HBe positive chronic HBV infection

In this study we have examined the density of HLA class I protein display on the hepatocytes of patients with HBe antigen (HBeAg) or anti-HBe (HBeAb) positive chronic hepatitis B virus (HBV) infection and related this to the level of interferon activation of these cells determined by measuring hepatic oligo 2-5A synthetase activity. In HBeAg positive patients the density of HLA class I (HLA-I) protein was not significantly increased above that found in uninfected liver, but levels of 2-5A synthetase were twice normal. In anti-HBe positive patients, HLA-I density was markedly increased in the presence of normal 2-5A synthetase activity. These data are consistent with type I (alpha or beta) interferon activation of the hepatocytes in HBeAg positive patients and type II (gamma) interferon activity in anti-HBe positive subjects.

Evidence for a deficiency of interferon production in patients with chronic hepatitis B virus infection acquired in adult life

Ninety per cent of patients infected in adult life with the hepatitis B virus clear the virus completely and 10% develop chronic infection. There is evidence for the involvement of interferon in the clearance of acute hepatitis B virus infection. We report that, in in vitro tests, some hepatitis B virus carriers have a reduced capacity to produce alpha- and gamma-interferon which is unrelated to the level of viral replication and to the severity of the liver disease and that the level of 2-5 oligoadenylate synthetase in their livers is only minimally elevated compared to controls. Treatment with lymphoblastoid (alpha-) interferon leads to a marked rise in 2-5 oligoadenylate synthetase activity. These data indicate that some patients with chronic hepatitis B virus infection acquired in adult life have a partial deficiency of production of alpha-interferon but can respond to exogenous alpha-interferon. These observations provide a logical basis for attempts to treat this condition with interferons.

Enhanced level of double-stranded RNA-dependent protein kinase in peripheral blood mononuclear cells of patients with viral infections

The protein kinase activity dependent on double-stranded RNA was assayed in extracts of peripheral blood mononuclear (PBM) cells from healthy volunteers and in patients with different types of virus infections. The protein kinase was assayed after one-step purification on an immunoaffinity column containing monoclonal antibody against the 68,000 Mr protein, a subunit of the protein kinase. In healthy individuals, the activity of the protein kinase remains constant. In contrast, the activity of the protein kinase is enhanced significantly in patients with viral infections and is decreased during the course of the disease in parallel with clinical ameliorations and reversal of clinical symptoms. There is a strong correlation between the enhanced levels of the protein kinase activity and another interferon-mediated enzyme, 2-5A synthetase. Both of these enzymes, therefore, could be used as markers to evaluate the state of the disease and recovery. In the different populations of lymphocytes, most of the protein kinase activity was found to be present in T and B lymphocytes, T lymphocytes showing a higher activity than B lymphocytes.

Enhancement of natural killer cell activity and 2-5A synthetase in operable breast cancer patients treated with polyadenylic; polyuridylic acid

Treatment of operable breast cancer patients with a single injection of 60 mg poly(A); poly(U) (polyadenylic, polyuridylic acid) resulted in an enhancement of natural killer (NK) cell cytotoxicity against human myeloid K562 target cells. Furthermore, the level of 2-5A synthetase in peripheral blood lymphocytes of such patients was increased after the treatment. Both of these effects, measured 24 and 48 hours after the injection of poly(A); poly(U), were statistically significant compared to their respective levels before the treatment. These events, therefore, may be used as markers to monitor the immediate response of patients toward treatment with this synthetic double-stranded RNA.

Serum interferon level and (2'-5')oligoadenylate synthetase activity in lymphocytes during clinical interferon application

Determinations of (2'-5')oligoadenylate synthetase (OAS) in extracts of peripheral mononuclear cells were used to monitor clinical treatment by human leukocyte-derived alpha-interferon (IFN-alpha). The maximum activity of this enzyme was detected about 6 h after the maximum IFN activity in the patient's serum, its half-life being severalfold longer than that of circulating IFN. Thus, even some days after its clearance, IFN can be detected by means of this enzyme. Sixfold increases of the IFN dose were not able to further increase OAS activity induced by doses of about 5 X 10(4) units/kg body weight in adult persons. Intravenous administration of IFN seems not to be superior to its i.m. injection.

Activated interferon system in healthy homosexual men

More than 50% of a group of healthy homosexuals in Israel were found to have an activated interferon (IFN) system as evidenced by markedly elevated blood IFN levels, increased in vitro production of IFN by unstimulated peripheral blood mononuclear cells and HuIFN-alpha and HuIFN-gamma production by appropriately stimulated cells, and a surprisingly high incidence of an antiviral state of cells. This pattern resembles that found in persons with acute viral illness, and is unlike that found in normal healthy controls. The type of IFN in the blood was found to be unusual in that it was mainly HuIFN-alpha, pH 2-labile, a type of IFN found in certain collagen diseases as well as in homosexual men suffering from Kaposi's sarcoma or lymphadenopathy. Natural killer (NK) cytotoxic activity was found to be somewhat lower than that found in normal controls, although no correlation was found between blood IFN levels and NK activity. Mean (2'-5')-oligoisoadenylate synthetase levels in cell extracts were intermediate between normal controls and patients with viral illness. Likewise no correlation was found between enzyme levels and blood IFN levels. The highly activated IFN system found in certain homosexuals, as well as the increased spontaneous production of IFN by unstimulated mononuclear cells, suggest the possibility of the presence of a virus, active or latent, in these individuals. This virus could be a retrovirus such as HTLV-III or LAV which have recently been isolated from AIDS patients. The special type of IFN present could be the response to a novel virus in an unusual situation. On the basis of recent reports, we speculate that homosexuals with highly activated IFN systems who produce pH 2-labile HuIFN-alpha could be at increased risk for developing AIDS.

Increased 2',5'-oligoadenylate synthetase activity in blood mononuclear leukocytes from patients with advanced cutaneous T-cell lymphoma

The activity of the interferon-induced enzyme 2',5'-oligoadenylate synthetase (2',5' An synthetase) was found to be increased in the lysates of peripheral blood mononuclear leukocytes obtained from 10 of 25 (40%) patients with cutaneous T-cell lymphoma (mycosis fungoides and Sézary syndrome). A positive association was found between the level of mean total synthetase activity and extent of involvement (stage) of disease. However, the leukocytes from two patients with relatively high proportions of neoplastic T-cells in the blood (Sézary syndrome) had negligible enzyme activity. It is speculated that increased interferon production in vivo may account for the observed enzyme changes in normal blood leukocytes from these patients, and that the neoplastic T-cell population is the most likely source of the presumed interferon production. Possible mechanisms and biologic consequences of high levels of endogenous interferon in patients with cutaneous T-cell lymphoma are discussed.

A sensitive immunoenzymometric assay for 2',5'-oligoadenylate. Detection of elevated 2',5'-oligoadenylate synthetase in human peripheral mononuclear cells

A competition immunoenzymometric assay for 2',5'-oligoadenylate was developed and employed to measure the interferon-inducible enzyme 2',5'-oligoadenylate synthetase in cell extracts. Microtiter plates coated with a novel conjugate of p5'A2'p5'A2'p5'A and N-(2-aminoethyl)-carbamylmethylated-Ficoll (AECM-Ficoll) bound rabbit polyclonal or mouse monoclonal antibody directed against 2',5'-oligoadenylate. Binding was inhibited by soluble 2',5'-oligoadenylate. Estimates of 2',5'-oligoadenylate concentrations based on inhibition of antibody binding compared favorably with those obtained using a protein synthesis inhibition assay. Low concentrations of 2',5'-oligoadenylate synthesized in vitro by extracts of human peripheral mononuclear cells were conveniently estimated using less than or equal to 10(6) cells. Virtually identical results were obtained when either total extract or synthetase bound to poly(I) . poly(C)-agarose was used for the in vitro incubation. When peripheral mononuclear cells were incubated in vitro with interferon, the normally low levels of 2',5'-oligo(A) synthetase rose dramatically. The assay was employed to measure synthetase levels in peripheral mononuclear cells isolated from patients with systemic lupus erythematosus. Some of these patients were found to have elevated levels of 2',5'-oligoadenylate synthetase.

Assay and the levels of 2-5A-synthetase in lymphocytes of patients with viral, bacterial and autoimmune diseases

The level of 2-5A-synthetase in extracts of peripheral blood lymphocytes was estimated by the capacity of the enzyme to synthesize 2-5A in the presence of ATP. The 2-5A was then purified on a small column of DEAE-cellulose. Here we show that under or experimental conditions, the amount of 2-5A formed is proportional to the level of the enzyme. The concentration of 2-5A (nmol of AMP/10(6) lymphocytes) in an assay therefore reflects the level of the enzyme. Enhanced levels of 2-5A synthetase were observed in the lymphocytes of patients with viral and bacterial infections. In most of the cases studied, these enhanced levels of the enzyme decreased during the course of infection parallel to recovery. Thus, the level of 2-5A synthetase may indicate the state of the disease and its evolution during the period of treatment; furthermore, it may be a useful marker in monitoring the return to a normal physiological condition. In addition to patients with viral and bacterial infections, enhanced levels of 2-5A synthetase were observed in patients suffering from autoimmune diseases. In five patients studied here, the enhanced levels of 2-5A synthetase remained high at different periods during the course of the disease. These results suggest the presence of circulating interferon throughout the disease.

Molecular cloning and sequence of partial cDNA for interferon-induced (2'-5')oligo(A) synthetase mRNA from human cells

By using a translation assay in oocytes, a 17S RNA fraction coding for the interferon-induced (2'-5')oligo(A) synthetase was purified from human cells. A cDNA library was prepared by cloning in Escherichia coli plasmid pBR322 and screened by positive hybridization-translation in oocytes. A cDNA clone corresponding to the (2'-5')oligo(A) synthetase mRNA was identified. In SV80 cells, this E cDNA recognizes three RNAs of 1.65, 1.85, and 3.6 kilobases, which are present only after interferon treatment of the cells. In Namalva cells, mainly one RNA of 1.8 kilobases is seen.