Patient-derived fibroblasts indicate oxidative stress status and may justify antioxidant therapy in OXPHOS disorders.

Oxidative phosphorylation disorders are often associated with increased oxidative stress and antioxidant therapy is frequently given as treatment. However, the role of oxidative stress in oxidative phosphorylation disorders or patients is far from clear and consequently the preventive or therapeutic effect of antioxidants is highly anecdotic. Therefore, we performed a systematic study of a panel of oxidative stress parameters (reactive oxygen species levels, damage and defense) in fibroblasts of twelve well-characterized oxidative phosphorylation patients with a defect in the POLG1 gene, in the mitochondrial DNA-encoded tRNA-Leu gene (m.3243A>G or m.3302A>G) and in one of the mitochondrial DNA-encoded NADH dehydrogenase complex I (CI) subunits. All except two cell lines (one POLG1 and one tRNA-Leu) showed increased reactive oxygen species levels compared with controls, but only four (two CI and two tRNA-Leu) cell lines provided evidence for increased oxidative protein damage. The absence of a correlation between reactive oxygen species levels and oxidative protein damage implies differences in damage prevention or correction. This was investigated by gene expression studies, which showed adaptive and compensating changes involving antioxidants and the unfolded protein response, especially in the POLG1 group. This study indicated that patients display individual responses and that detailed analysis of fibroblasts enables the identification of patients that potentially benefit from antioxidant therapy. Furthermore, the fibroblast model can also be used to search for and test novel, more specific antioxidants or explore ways to stimulate compensatory mechanisms.

Idiotypic regulation of the immune system. Common idiotypic specificities between idiotypes and antibodies raised against anti-idiotypic antibodies in rabbits.

Anti-idiotypic antibodies (Ab2) were raised in allotype-matched rabbits against anti-carbohydrate or anti-tobacco mosaic virus antibodies (Ab1). Several Ab2 were purified and injected into a third series of rabbits III which synthesized antiantiidiotypic antibodies (Ab3). Antigen was then given for the first time in those rabbits who had synthesized Ab3. The specific antibody synthesized in rabbits III was called Ab1'. Anti-idiotypic antibodies were raised against purified Ab3 antibodies (Ab4). In most cases, Ab1' antibodies are sharing idiotypic specificities with Ab1. Ab3 did not react with antigen but shared idiotopes with Ab1 and Ab1' because Ab4 antibodies, which are anti-idiotypes to Ab3 do recognize specifically Ab1 and Ab1' antibodies belonging to the same chain of immunization. It seems therefore that Ab3 looks idiotypically like Ab1 and Ab4 displays the same behaviour as Ab2. A general view of the functioning of the immune system is presented.

Soluble CD23 and other receptors (CD4, CD8, CD25, CD71) in serum of patients with chronic lymphocytic leukemia.

We measured the soluble (s) receptors CD23, CD8, CD4, interleukin-2 receptor (IL-2R, CD25), and transferrin receptor (TfR, CD71), in normal serum and in patients with chronic lymphocytic leukemia (CLL) and evaluated them in relation to clinical and biological parameters of the disease, as well as serum immunoglobulin E (IgE). Compared to 31 normal individuals, 42 CLL patients had increased levels of sCD23 (98.4 +/- 127.7 versus 0.9 +/- 0.3 U/ml, p < 0.001), sIL-2R (6080 +/- 7030 versus 1420 +/- 640 pg/ml, p < 0.001), sTfR (12,100 +/- 11,250 versus 5000 +/- 1050 ng/ml, p < 0.001), and sCD8 (510 +/- 191 versus 234 +/- 89 U/ml, p < 0.001), but normal sCD4 levels. Mean sCD23 levels remained normal in patients with non-Hodgkin's lymphoma (other than small lymphocytic), Hodgkin's disease, hairy cell leukemia, acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), chronic myelogenous leukemia (CML), multiple myeloma, or solid tumors. Advancing Rai clinical stage was associated with a progressive elevation of sCD23 (p < 0.001), while sCD8 (p < 0.05), sIL-2R (p < 0.001), and sTfR (p < 0.005) were highest in stage 2 patients. Discriminant analysis confirmed the value of soluble receptor determinations in the clinical evaluation of CLL patients. sCD23 correlated with sIL-2R (p < 0.001) and sTfR (p < 0.05) but not with sCD4 or sCD8, and displayed an inverse relationship with serum IgE (NS) and total gamma-globulin (p < 0.05). sIL-2R correlated with sCD23 (p < 0.001), sTfR (p < 0.001), sCD4 (p < 0.01), and sCD8 (p < 0.01). The lymphocyte count correlated with serum lactate dehydrogenase (LDH) (p < 0.05), sCD23 (p < 0.001) and sIL-2R (p < 0.01) but not sTfR, sCD8, or sCD4. Chemotherapy produced consistent reductions of sCD23 levels in two responding patients. We conclude that: (i) sCD23 is considerably elevated in CLL, correlates with the tumor mass and clinical stage, and could be helpful in monitoring these patients; and (ii) sIL-2R, sCD8, and sTfR levels are less specifically increased and could be influenced by other factors such as immune activation and erythropoiesis.

Immunochemical characterization of antigenic domains on human IL-2: spatially distinct epitopes are associated with binding to the p55 and p70 subunits of IL-2 receptor.

We have isolated and characterized 8 mAb against human rIL-2. All recognize nonglycosylated rIL-2 in liquid phase with similar affinities (Kd approximately 1 nM). Based on the epitopes of the IL-2 molecule that they recognize and their pattern of reactivity against glycosylated and non-glycosylated IL-2, they have been classified into four groups. The first group of anti-IL-2 mAb (2C4, 19B11 and 12C2) inhibits IL-2 binding to p70 IL-2R, while the second one (16F11, 18E1 and 2A4) prevents its binding to p55 IL-2R. These two groups neutralize IL-2 activity in a T cell proliferation assay equally well, due to their similar inhibition of IL-2 binding to high affinity IL-2R. Two mAb, 3H9 and 17F4, recognize separate epitopes on IL-2 molecule, are poor inhibitors of IL-2 binding, and they are inefficient in the neutralization of its biological activity; they have been assigned to the third and fourth groups, respectively. These results show that mAb from the first and second group recognize two epitopes of the human IL-2 molecule which probably overlap the p70 IL-2R and p55 IL-2R binding sites, respectively. In addition, these areas together form the high affinity IL-2R binding site. The two mAb from the third and fourth group recognized epitopes of IL-2 not directly involved in IL-2 binding to its receptor. All eight mAb anti-human IL-2 recognize murine IL-2 and with the exception of one, 17F4 mAb are also able to neutralize it in a T cell proliferation assay. The relationship between the structure and the function of the IL-2 molecule is discussed.

Characterization of a monoclonal antibody directed against the NH2 terminal area of interleukin-2 (IL-2) and inhibiting specifically the binding of IL-2 to IL-2 receptor beta chain (IL-2R beta).

An anti-human IL-2 mAb (19B11/beta) was found to selectively block the binding of IL-2 to TS1 beta cells expressing the interleukin-2 receptor beta (IL-2R beta) without affecting binding to TS1 alpha cells expressing the IL-2R alpha receptor. It also specifically inhibits the IL-2 driven cell proliferation in TS1 beta cells. These observations have lead to the hypothesis that its epitope is related to an IL-2 area involved in binding with IL-2R beta chain. This epitope was identified using various peptides covering the N-terminal half (including alpha helix A) of the 133 amino acids of IL-2. MAb 19B11/beta does not recognize peptides 30-54 and 44-54 but recognizes peptides 1-22 and 1-30 with a good affinity. Furthermore, threonine in position no. 3 was found to be critical for the binding of mAb 19B11/beta. A relationship between the epitope of mAb 19B11/beta and the glycosylation of the IL-2 molecule was observed. This further demonstrates that the NH2 terminal area of IL-2 is critical for IL-2/IL-2R beta interactions. Two other mAbs were studied during the course of this work. They served as control for the study of mAb 19B11/beta and provide some additional insight concerning the question of IL-2/IL-2R structure-function. MAb 16F11/alpha selectively blocks the IL-2 binding to TS1 alpha cells. The epitope of mAb 16F11 is conformational and it was not possible to study the corresponding IL-2/IL-2R alpha region of interaction. Epitope of mAb 3H9 is localized between residues 30 and 54 and does not affect the binding of IL-2 to IL-2R alpha.

Human monocytoid cell lines as indicators of endotoxin: comparison with rabbit pyrogen and Limulus amoebocyte lysate assay.

The aim of this study was to develop an in vitro test system for pyrogenic substances. Three clones derived from human monocytoid cell lines, which were selected by their high sensitivity to lipopolysaccharide (LPS), were assessed for tumor necrosis factor (TNF) production. Their response to pyrogen-containing samples was compared with that in a Limulus amoebocyte lysate assay and the rabbit pyrogen test. We show here that the induction of TNF in these clones is a valid in vitro alternative to determine endotoxin in commercial preparations requiring pyrogenicity testing. Cell clones derived from Mono Mac 6 (MM6 2H8 and MM6 4B5) responded to sub-ng/ml concentrations of complete rough-strain and smooth-strain LPS, to ng/ml concentrations of diphosphoryl-lipid A, and to microgram/ml concentrations of monophosphoryl-lipid A and to detoxified LPS. Cells reacted to > or = 1 microgram/ml lipoteichoic acid by TNF production, and were relatively insensitive to toxic shock syndrome toxin-1 (TSST-1) and to muramyl dipeptide adjuvant peptide. The reaction pattern of a clone derived from THP-1 (THP-1 1G3) was in general, similar to that of the MM6 clones, except that THP-1 1G3 failed to react to diphosphoryl-lipid A. When tested on commercial samples destined for parenteral use, there was a close correlation between a sensitive Limulus amoebocyte lysate (LAL) test and the cell culture test on the one hand, and between the pyrogen test and the cell culture test on the other hand. The data suggest that this cell-based test is able to recognize pyrogens derived from gram-negative organisms in test samples with appropriate sensitivity and specificity. This test appears to be able to eliminate some of the false-positive data obtained in the LAL test.

Characterisation of monoclonal antibodies against human interleukin-10 and their use in an ELISA for the measurement of this cytokine.

Biological and biochemical characteristics of monoclonal antibodies (MABs) raised against human interleukin-10 (IL-10) are described as well as their use in the design of a specific ELISA for the measurement of the cytokine. 21 murine anti-human interleukin-10 (IL-10) MABs were obtained by fusion of splenocytes from mice immunized against human recombinant IL-10 with SP2/0 myelomatous cells. These antibodies define three major antigenic areas on the IL-10 molecule, one of which comprises epitopes involved in receptor binding and induction of biological activity. They recognize recombinant human IL-10 with affinities ranging from 1.3 x 10(-7) to 3 x 10(-11), as well as natural IL-10. Most of them also recognize viral IL-10 (vIL-10) encoded by the Epstein-Barr virus (EBV). A specific human-IL-10 ELISA has been developed using two MABs (18 and 19) as capture antibody and one MAB (17) as detector. The sensitivity (3 pg/ml), precision (intra-assays < 4%), reproducibility (interassay < 3%), and accuracy (recoveries, ranging between 84 and 107%, in several fluids) of the assay, plus its excellent performance in dilution tests, and the lack of interference when in the presence of possible cross-reactive substances, permits accurate cytokine measurement in biological fluids such as serum, plasma, bronchoalveolar lavage, urine and culture supernatants. Using the assay, IL-10 was measurable in the plasma of patients with septic shock (range 11-2740 pg/ml) whereas IL-10 plasma levels were < 7.8 pg/ml in healthy volunteers.

Novel method for the measurement of cytokine production by a one-stage procedure.

A new one-step culture-immunoassay procedure is described for testing cytokine production by immunocompetent cells in whole blood (WB) without the need for an isolation step. Briefly, WB samples or distilled water were added to RPMI medium containing specific anti-cytokine peroxidase-labelled monoclonal antibodies and incubated in micro-well plates coated with specific capture monoclonal antibodies, directed against distinct epitopes of the cytokine, and containing dried polyclonal activators (5.625 micrograms LPS + 1.125 micrograms PHA) or dried standards respectively. The optimalisation of the assay is described for an extended measurement range. The best compromise between sensitivity and linearity was obtained with the addition of 50 ng/well for TNF-alpha and IL-6 or 100 ng/well for IFN-gamma of unconjugate antibodies to the corresponding conjugate. The kinetics of individual production of each cytokine in WB of normal healthy donors showed values entering the standard range following incubation times of between 2 and 8 h for TNF-alpha, 2 and 4 h for IL-6, and 4 and 24 h for IFN-gamma. The sensitivity, the precision (intra-assay CVs) and the reproducibility (interassay CVs) of the assays were as follows: 70 pg/ml, < or = 14% and < or = 11% for TNF-alpha; 25 pg/ml, < or = 11% and < or = 16% for IL-6; 25 pg/ml, < or = 19% and < or = 20% for IFN-gamma. The accuracy (% of recovery) of the assays was in the order of 100% and between 40 and 60% in the absence or presence of polyclonal activators, reflecting the occurrence of an active production/consumption mechanism during the activation.

An ELISA for the measurement of human leukemia inhibitory factor in biological fluids and culture supernatants.

A new monoclonal antibody-based ELISA for leukaemia inhibitory factor/human interleukin for DA cells (LIF/HILDA) measurements is described. The sensitivity (56 pg/ml after 4 h incubation, 14 pg/ml after 24 h incubation), precision (intra-assays < 5%), reproducibility (interassay < 10%), and accuracy (recoveries, ranging between 98 and 119%, in several fluids) of the assay, plus its excellent performance in dilution tests, and the lack of interference when in the presence of possible cross-reactive substances guarantee accurate cytokine measurement in biological fluids such as serum, plasma, synovial fluid, follicular fluid, urine and culture supernatants. Using the assay, LIF/HILDA was measurable in supernatants after in vitro whole blood stimulation with phytohemagglutinin (PHA), OKT3, and phorbol myristate acetate (PMA) but not with lipopolysaccharide (LPS) or Ca ionophore. LIF/HILDA production was not measurable until after 24 h of culture, when cytokine levels were seen to increase linearly in the supernatant to reach values of up to 40 ng/ml after 96 h of culture. Finally, a good correlation was found (r = 0.96; p < 0.0001; y = 23.1x + 233) between the LIF/HILDA values obtained using the ELISA and DA-1a bioassay.

Optimal control of interferon-gamma and tumor necrosis factor-alpha by interleukin-10 produced in response to one HLA-DR mismatch during the primary mixed lymphocyte reaction.

Interleukin (IL)-10 is an immunosuppressive cytokine potentially involved in the control of the allogeneic response. Several studies failed to detect it in mixed lymphocyte reaction supernatants. However, experiments using IL-10-specific antibodies, revealing its inhibitory action on interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha, provided indirect evidence that endogenous IL-10 was produced. The aim of the present work is to elucidate the role of IL-10 during mixed lymphocyte reaction and to investigate the influence of HLA-DR antigens on its production and on the regulatory loop involving TNF-alpha and IFN-gamma. Using a highly sensitive ELISA, a significant (P < 0.0001) but low IL-10 release could be detected (33.7 +/- 3.6 pg/ml) in response to HLA-DR disparities. However, IL-10 release was not graded as 1 DR mismatch (MM)-induced maximal secretion (32.3 +/- 5.1 pg/ml). This contrasted with TNF-alpha and IFN-gamma productions, which significantly increased in 2 DR MM pairs. Addition to IL-10-specific antibodies resulted in higher enhancement of INF-gamma (235 +/- 38% vs. 122 +/- 39%, P = 0.02) and, to a lesser extent, TNF-alpha (147 +/- 56% vs. 112 +/- 20%, NS) in 1 compared with 2 DR MM pairs. We conclude that the 1 DR MM setting is associated with optimal IL-10 secretion and more efficient inhibition of IFN-gamma and TNF-alpha compared with the 2 DR MM configuration. Although promoting enhanced IFN-gamma and TNF-alpha release, introduction of an additional DR MM does not result in increased IL-10 production. These data indicating that the IL-10 regulatory feedback loop is more effective in 1 DR rather than complete DR incompatibility could have an impact on matching policies for planned transfusion.

Tumor necrosis factor-alpha and interleukin-6 production induced by variations of DR4 polymorphism during the primary mixed lymphocyte reaction.

Serologically defined MHC class II differences provoke release of TNF-alpha and IL-6 during MLR. In order to assess the influence of micropolymorphism defined at the genomic level, we selected informative donors pairs within DR2 DR4 serologically defined unrelated subjects by combining those differing only by DR4 alleles, as assessed by PCR-SSOP (DRB1*0401 to 07). Two groups of MLR combinations were tested including DRB1-identical (group 1, n = 12) and one DRB1 difference (group 2, n = 16). Pairs of HLA-identical siblings (n = 4) and of unrelated subjects differing by two major DR incompatibilities detected by serology (n = 27) were used as controls. We further investigated whether DP and DQ differences contributed to the observed CK production. Comparison of group 2 with group 1 showed that one DRB1 difference had a marked influence on CK production at day 3 (TNF-alpha: 401.8 +/- 85 pg/ml vs. 128.7 +/- 34.5 pg/ml, P = 0.001; SI = 2.97 +/- 0.23 vs. 1.27 +/- 0.09, P < 0.0001; IL-6: 317.6 +/- 44.8 pg/ml vs. 108 +/- 13 pg/ml, P = 0.003; SI = 2.53 +/- 0.37 vs. 1.11 +/- 0.05, P < 0.0001). However, CK release in group 2 was significantly lower than that observed in subjects with two serologically defined DR differences (TNF-alpha: 515.1 +/- 61.4 pg/ml, P = 0.05; SI = 5.61 +/- 0.48, P < 0.0001; IL-6: 545.9 +/- 75.8 pg/ml, P = 0.03; SI = 4.75 +/- 0.58, P < 0.0004). Addition of LPS after one day of MLR resulted in discriminant production of CK in group 2 as compared with group 1. Neither DP nor DQ differences affected CK production. In conclusion, DR subtypic differences induce significant CK release during primary MLR. This in vitro study demonstrates the immunodominance of the DR system in eliciting strong inflammatory mediators release.

In vivo soluble tumor necrosis factor receptor release in OKT3-treated patients. Differential regulation of TNF-sR55 and TNF-sR75.

Administration of monoclonal antibodies to CD3 triggers acute and massive release of several cytokines, including tumor necrosis factor alpha (TNF-alpha), essentially T cell-derived. This cytokine release is responsible for the spontaneously reversible acute clinical syndrome observed in most OKT3-treated patients. We found that the first OKT3 injection in human renal allograft recipients led to the release in significant amounts of soluble TNF receptors (TNF-sR55 and TNF-sR75) that are considered main natural inhibitors of TNF bioactivity. As for OKT3-induced TNF-alpha, peak TNF-sR levels were observed 1 hr postinjection, and this release was limited to the first monoclonal antibody injection. A distinct regulation of OKT3-mediated release of TNF-sR75 and TNF-sR55 was observed, since (1) in clear contrast with OKT3-mediated TNF-sR75 induction, TNF-sR55 release was completely blocked by a high dose of corticosteroids prior to OKT3 injection and (2) secretion of TNF-sR75 but not TNF-sR55 correlated with immunoreactive TNF-alpha release. In hemodialyzed patients prior to transplantation and OKT3 treatment, a condition characterized by chronic TNF-alpha release, TNF-sR efficiently block TNF bioactivity. In contrast, the system is overwhelmed by the massive acute TNF-alpha release that follows the first OKT3 injection: in such a condition TNF-sR looses its capacity to counteract TNF bioactivity.

The effect of UVB irradiation on proliferative activity and cell growth potential of cord blood.

To determine the degree of graft versus host disease (GVHD) prophylaxis that might be necessary if cord blood (CB) transplantation is more widely applied, we compared human cord blood mononuclear cell (CBMC) and adult peripheral blood mononuclear cell (PBMC) proliferative responses and stimulatory capabilities; to examine the utility of UVB irradiation for GVHD prophylaxis, we compared proliferative responses, antigen-presenting cell (APC) stimulatory functions, and cytokine production by untreated and UVB-irradiated CBMCs. The two cell types, CBMC and PBMC, proliferated equally both in response to phytohemagglutinin (PHA) and alloantigen in mixed lymphocyte culture (MLC). Cord blood stimulatory function in MLC was significantly (P < 0.05) reduced to 60% of PBMC stimulatory capability. Ultraviolet-B irradiation at a dose of 100 J/m2 of CBMCs significantly (P < 0.01) inhibited PHA stimulation by 79.4%, reduced responder activity in MLC by 75.8%, and inhibited stimulatory activity in MLC by 55.6% as compared with the activity shown by untreated CBMCs. The same dose of UVB preserved 59.9% of CFU-GM and 65.9% of BFU-E colony growth as compared with untreated CBMCs. Production of lymphokines (IL-2, GM-CSF, LIF, and gamma-IFN) by PHA-stimulated CBMCs was decreased, but monokine (IL-1 beta and IL-6) production was unchanged. We conclude that UVB irradiation at a dose of 100 J/m2 inhibits CB lymphocyte activation and preserves the cellular growth potential of CB hematopoietic progenitor cells.

CD3 antibody-induced IL-10 in renal allograft recipients: an in vivo and in vitro analysis.

BACKGROUND: The first administration of CD3 monoclonal antibodies, such as anti-human CD3 (OKT3), induces a massive release of several cytokines, including tumor necrosis factor alpha (TNF-alpha), interferon (IFN)-gamma, interleukin (IL)-2, IL-3, IL-6, and granulocyte-macrophage colony-stimulating factor. METHODS: Cytokine levels in patient's sera were measured by specific ELISA. In vitro cultures were performed using OKT3-stimulated peripheral blood mononuclear cells and/or whole blood from patients and normal controls. RESULTS: Here we describe that OKT3 administration to human renal allograft recipients also leads to a significant release of IL-10. Contrasting with most OKT3-induced cytokines, such as TNF-alpha whose release is transient, IL-10 levels show a more progressive increase, they peak only by 4-8 hr after the first OKT3 injection and persist longer. Thus, significant IL-10 levels are still detectable at the time of the second and the third OKT3 injection. Administration of corticosteroids, 1 hr before the first OKT3 injection, significantly reduced both TNF-alpha and IL-10 release. Experiments were performed to evaluate the source(s) of IL-10 and its (their) influence on the initial T-cell activation. When stimulated in culture with soluble OKT3, the production of IL-10 was dependent on the cooperation between T lymphocytes and monocytes. It is important that, as assessed through the use of a specific neutralizing antibody, the endogenous IL-10 produced in the co-culture system exerted a negative feed-back on the release of the other pro-inflammatory CD3-induced cytokines, which was reproducible. CONCLUSION: These results are supportive of a major role of IL-10 in the down-modulation of the OKT3-triggered T-cell activation cascade.

Modulation of LIF expression in human melanoma cells by oncostatin M.

Oncostatin M (OSM) and leukemia inhibitory factor (LIF) are involved in stimulation of acute-phase protein during inflammatory processes. We recently suggested that these two cytokines may play a role in human immune surveillance during tumor progression. The present study was designed to determine the capacity of OSM in modulating LIF production by human tumor cells and to provide a better definition of the interactions between these two molecules during inflammatory reaction due to neoplasia. LIF content in culture supernatants was assayed by a specific ELISA (sensitivity: 25 pg/ml). In vitro exposure to recombinant OSM increased LIF production 2 to 6-fold in all human melanoma cell lines tested. This effect was not limited to melanoma cell types since LIF production was also enhanced by an MDA breast undifferentiated adenocarcinoma line. Moreover, a synergistic effect was observed for OSM and TNF-alpha. LIF increase was apparently due to up-modulation through LIF synthesis since LIF transcript expression was also enhanced in these tumor cell lines. It is concluded that OSM can induce inflammatory reaction not only directly but also via LIF production by tumor cells.

Plasma levels of sTNFR p75 and IL-8 in patients with HIV-1 infection.

We determined the degree of activation of the TNF alpha system and the levels of IL-8 in HIV-1 infection. TNF alpha is one of the most potent agents for the induction of IL-8. TNF alpha may be cleared rapidly from the circulation, however soluble tumor necrosis factor receptor (sTNFR) p75 which is more stable may reflect the degree of activation of the TNF alpha system. We measured concentrations of sTNFR p75 and IL-8 with immunoassays in the plasma of 99 HIV-1-infected patients at different stages of disease (Centers for Disease Control classification) and in 20 healthy control subjects. Plasma levels of sTNFR p75 were elevated in most of the asymptomatic seropositive patients without CD4+ T cell depletion (Stage IIA) and in most of patients of all clinical groups compared with controls. However, in the majority of those patients plasma levels of IL-8 were not higher than those of controls. Our results suggest that sTNFR p75 levels but not IL-8 levels in circulating blood are high in the course of HIV-1 infection.

Enhanced TNF alpha production by monocytic-like cells exposed to dengue virus antigens.

The studies indicating the importance of TNF alpha in dengue virus infection have led us to determine whether monocyte-like cells produce TNF alpha exposure after dengue virus. The supernatant fluids of mosquito cells (AP61) infected with dengue virus (DV) type 1 and DV type 3 were harvested 7 days post-infection and clarified. DV inactivation was performed in the presence of betapropiolactone that preserves antigenicity of viruses. We used the monocytic-like cell line THP-1 that is a model system of TNF alpha production. Polymyxin B (50 micrograms/ml) was added to block untoward effects resulting from possible LPS contamination of media or cultures. THP-1 cells were primed with a phorbol ester (PMA) for 24 h, then they were cultured for 4 and 24 h in the presence of inactivated culture supernatant of dengue infected AP61 cells or control preparations. The concentrations of TNF alpha in the culture supernatants were measured by using an immunoenzymatic assay. PMA-treated THP-1 cells rapidly secreted TNF alpha in response to inactivated culture supernatant of DV-infected cells. We found high levels of TNF alpha with cells exposed to DV1 and DV3 preparations compared with controls (mean values; 465 and 829 vs. 70 pg/ml, respectively, at 24 h post exposure, n = 4). We obtained a substantial inhibition of the enhancing activity of DV1 and DV3 infected supernatants in the presence of dengue hyperimmune mouse ascitic fluids. Our results demonstrate that exposure of monocytes/macrophages to DV particles or virus proteins derived from DV may be responsible for the enhanced production of TNF alpha in DV-infected patients.

Serum soluble CD23 levels in giant cell arteritis.

Lymphocytes and monocytes express various levels of membrane-bound CD23, the low affinity receptor for IgE (Fc epsilon RII), and in some cases release it as a soluble form. Soluble CD23 (sCD23) has been implicated in the regulation of many immunological functions of T and B lymphocytes, macrophages and myeloid cells in humans. To study serum sCD23 levels in inflammatory conditions, we selected a systemic disease sensitive to corticotherapy, the giant cell arteritis, which is characterized by an inflammation of the temporal artery. Serum sCD23 levels, as measured by a radioimmunoassay, were increased in these patients, and returned to normal values within the 24 h following initiation of corticotherapy. The data suggest that the increase in sCD23 levels in giant cell arteritis results from an overproduction.

Soluble tumor necrosis factor receptor type II (sTNFRII) in HIV-infected patients: relationship with the plasma level of HIV-1 RNA.

The value of soluble receptor for tumor necrosis factor type II (sTNFRII) as a strong and early predictor of HIV disease progression was suggested. Recently it has been reported that sTNFRII may provide an indication of the HIV load. In this work we focused on the relationship between sTNFRII and HIV burden in 95 HIV-1+ patients without AIDS grouped according to the 1993 classification of the CDC as group A, n = 55, and group B, n = 40. Compared with healthy controls, higher values of sTNFRII were obtained in all groups of HIV-1 infected patients (P < 0.001), but we found no inverse correlation between sTNFRII and CD4+ lymphocyte counts in CDC group A and B of the disease, and no correlation with log RNA copy number in patients with CD4 T-cell counts > 499/microl. A correlation was obtained between sTNFRII and the viral load in patients with CD4 T-cell counts ranging from 200 to 499/microl, but only in CDC group B patients (P < 0.01, n = 26). There was no correlation between the variations of sTNFRII and HIV-1 RNA levels in 19 CDC group A and 15 CDC group B clinically stable patients in the course of a short follow up. The plasma level of sTNFRII do not appear as a valuable surrogate marker of the plasma level of HIV-1 RNA in patients. Further investigations are needed to define the mechanism of the raised level of sTNFRII in HIV-1 infected patients.

Interleukin 12 unmasks HLA class I differences during mixed lymphocyte reaction induced interferon gamma production.

We investigated the genetic control of IFN-gamma release during MLR and its relationship with TNF-alpha and IL-12. Blocking experiments demonstrated the IFN-gamma dependence of TNF-alpha production and the significant contribution of IL-12 to IFN-gamma secretion. We studied informative pairs allowing the evaluation of the relative importance of HLA class I and class II antigens. Maximal IFN-gamma secretion allowing discrimination between fully HLA different and identical subjects required 5 days. In class I different but DRB1 identical pairs, a moderate but discriminant IFN-gamma release was found. Exogenous IL-12 addition after 24 hours of preactivation by MLR resulted in a marked enhancement of IFN-gamma production at day 2. In pairs differing only by class I antigens, the discriminating capacity was significantly increased as compared to values obtained in absence of IL-12 at day 2 (p < 0.004) and at day 5 (p < 0.004). The crucial role of class I antigens on IFN-gamma release was further substantiated by the blocking action of the W6/32 mAb directed against a monomorphic epitope common to all HLA-A, -B, and -C antigens. We conclude that IFN-gamma production during MLR is under the control of class I antigens. Furthermore, exogenous IL-12 strongly amplifies their influence.