Testosterone inhibits immunoglobulin production by human peripheral blood mononuclear cells

We studied the in vitro effect of testosterone on spontaneous immunoglobulin production by human peripheral blood mononuclear cells (PBMC). Testosterone inhibited IgG and IgM production by PBMC both from males and females. The inhibitory effect of testosterone was revealed at doses more than 1 nm, increased dose-dependently, and reached a plateau at 100 nm. At doses <1000 nm, testosterone did not reduce cell viability. Testosterone treatment reduced IgG production by 59.0% and that of IgM by 61.3% compared with control. Immunoglobulin production by B cells was also suppressed by testosterone, though the magnitude of the suppressive effect on B cells was lower than that on whole PBMC; testosterone-induced decrease of IgG production compared with control was 26.9% and that of IgM was 24.9%. Exogenous IL-6 partially restored the impaired immunoglobulin production of testosterone-treated PBMC; IgG production in testosterone culture was increased by IL-6 from 35.6% to 66.5% of control and that of IgM was also increased from 38.9% to 71.2%, respectively. Testosterone treatment reduced IL-6 production of monocytes by 78.4% compared with control, but neither affected that of T cells or B cells. These results suggest that testosterone may suppress immunoglobulin production of human PBMC directly by inhibiting B cell activity and indirectly by reducing IL-6 production of monocytes. It is thus indicated that this hormone may have protective and therapeutic effects on human autoimmune diseases.     

Interleukin-12 suppresses immunoglobulin E production but enhances immunoglobulin G4 production by human peripheral blood mononuclear cells.

The effect of interleukin-12 (IL-12) on human immunoglobulin G4 (IgG4) and IgE production was examined with cells derived from filarial patients and European controls. IL-12 inhibited IgE release but enhanced IgG4 production in cultures of peripheral blood mononuclear cells stimulated with anti-CD2 plus IL-2. When purified T- and B-cell cocultures were examined, IL-12 again markedly enhanced IgG4, whereas IgE production was no longer inhibited.     

Modulation of immunoglobulin production and cytokine mRNA expression in peripheral blood mononuclear cells by intravenous immunoglobulin

Intravenous immunoglobulin (IVIG) has the potential to regulate Ig production, but the mechanism(s) responsible for this effect is unknown. In experiments reported here, we examined the ability of IVIG to regulate Ig production in human peripheral blood mononuclear cells (PBMCs) stimulated with pokeweed mitogen (PWM). IVIG (2–10 mg/ml) showed a potent (80–85%) inhibition of PWM-stimulated IgG, IgM, and IgA production. To determine more precisely how IVIG mediated the inhibition of Ig production, we studied Ig promoting cytokine gene expression after PWM stimulation with or without IVIG (2 and 10 mg/ml) using dot-blot techniques. RNA was isolated from PBMCs at predetermined time points and probed with cDNAs specific for human cytokines (IL-1-, IL-2, IL-2R, IL-4, IL-5, IL-6, -IFN, and TNF-). IL-6 mRNA accumulation was maximal at 4.5 hr post-PWM stimulation and was inhibited 64–75% when IVIG (10 mg/ml) was present. -IFN mRNA levels peaked at 72 hr poststimulation and were also 68–75% inhibited by IVIG. IL-2 mRNA levels peaked at 4.5 hr and were 23–46% inhibited by IVIG. The inhibitory effect of IVIG on production of these cytokines (IL-6 and -IFN) was also observed at the protein level in sonicated PBMCs after incubation with PWM and IVIG. The mRNA levels for other cytokines were not or only minimally inhibited by IVIG. Addition of IL-6, -IFN, or IL-2 partially restored Ig production in IVIG-treated PWM-stimulated cultures, suggesting that inhibition of other cytokines or another mechanism(s) independent of cytokine inhibition might also be involved, although inhibition of IL-6, -IFN, and IL-2 may be one of the critical factors in the suppression of Ig production by IVIG.     

IL-12 inhibits in vitro immunoglobulin production by human lupus peripheral blood mononuclear cells (PBMC)

Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease characterized by polyclonal B cell activation and by the production of anti-double-stranded (ds) DNA antibodies. Given the inhibitory effects of IL-12 on humoral immune responses, we investigated whether IL-12 displayed such an activity on in vitro immunoglobulin production by SLE PBMC. Spontaneous IgG, IgG1, IgG2, IgG3 and IgM antibody production was dramatically reduced by addition of IL-12. These results were confirmed by Elispot assays detecting IgG- and anti-dsDNA-secreting cells. While IL-6 and TNF titres measured in PBMC supernatants were not modified by addition of IL-12, interferon-gamma (IFN-γ) titres were up-regulated and IL-10 production down-regulated. Since addition of IFN-γ did not down-regulate immunoglobulin production and since the inhibitory activity of IL-12 on immunoglobulin synthesis was not suppressed by anti-IFN-γ antibody, we concluded that the effect of IL-12 on immunoglobulin production was not mediated through IFN-γ. Our data also argue against the possibility that down-regulation of endogenous IL-10 production was responsible for the effect of IL-12. Thus, inhibition of IL-10 production by IFN-γ was not accompanied by inhibition of immunoglobulin production, and conversely, restoration of IL-10 production by anti-IFN-γ antibody did not suppress the inhibitory activity exerted by IL-12 on immunoglobulin production. Taken together, our data indicate that reduction of excessive immunoglobulin and anti-dsDNA antibody production by lupus PBMC can be achieved in vitro by IL-12, independently of IFN-γ and IL-10 modulation.     

Acid-labile human interferon alpha production by peripheral blood mononuclear cells stimulated by HIV-infected cells

Summary We compared the properties of interferon (IFN) induced in peripheral blood mononuclear cells (PBMC) by free infectious HIV to that induced by HIV-infected cells fixed with glutaraldehyde. While the IFN induced by HIV was a conventional IFN alpha, the IFN induced by HIV-infected cells, although sharing with IFN alpha both antigenic properties and molecular weight, was strongly inactivated by treatment at pH lower than 4. The ability to induce acid-labile IFN alpha was exerted both by the chronically—infected cell line H9/HIV and by normal PBMC infected in vitro with HIV, while infection of inducers cells with viruses other than HIV made these cells capable of inducing only acid-stable IFN alpha. The cell involved in the production of this type of IFN seems to be B-lymphocyte.Because the presence of acid-labile IFN alpha in the serum of AIDS patients has been described, we suggest that this unusual IFN derives from interaction between circulating B-lymphocytes and the HIV-infected cells.     

Calcium-pterin suppresses mitogen-induced tryptophan degradation and neopterin production in peripheral blood mononuclear cells

Antitumor activity of a calcium-pterin suspension has been described in vitro and in animal model systems. Recent studies provide some evidence that this effect involves immune-mediated mechanisms. We investigated the influence of calcium-pterin on freshly isolated human peripheral blood mononuclear cells (PBMC) stimulated with the mitogens phytohaemagglutinin and concanavalin A in vitro. Influence of calcium-pterin on tryptophan-degrading enzyme indoleamine (2,3)-dioxygenase (IDO) and on neopterin production was monitored in supernatants of cells. Increased neopterin concentrations as well as accelerated tryptophan degradation have been found to predict poor prognosis in patients with cancer, and both these immunobiochemical pathways are induced by the pro-inflammatory cytokine interferon-γ.

Compared to unstimulated cells, mitogens induced degradation of tryptophan and formation of neopterin in PBMC, and upon addition of calcium-pterin, both biochemical results were suppressed in a dose-dependent way. Thus, calcium-pterin suppresses immunological pathways in vitro that in patients with malignant diseases characterize an unfavorable prognosis. The effect of the compound to suppress IDO activity could be of considerable relevance for the antitumoral effect of the compound because activation of the enzyme is considered as an immune-escape mechanism of tumor cells.     

Suppression of immunoglobulin production in human peripheral blood mononuclear cells by monocytes via secretion of heavy-chain ferritin

In vitro antigen stimulation of peripheral blood mononuclear cells (PBMCs) does not induce immunoglobulin (Ig) production. However, pretreatment of PBMCs with l-leucyl-l-leucine methyl ester (LLME) prior to in vitro stimulation removes the suppression of Ig production. In the present study, we attempted to identify the target cells of LLME and determine the mechanisms by which Ig production in PBMCs is suppressed. We found that CD14⁺ monocytes are involved in the suppression of Ig production in PBMCs. Furthermore, we confirmed that heavy-chain ferritin derived from CD14⁺ monocytes suppresses Ig production in PBMCs, possibly through iron sequestration.     

Interleukin 1 production by peripheral blood mononuclear cells from leprosy patients.

Quantitation of interleukin 1 production by adherent mononuclear cells from peripheral blood was performed in patients with tuberculoid and lepromatous forms of leprosy. Cells from patients with tuberculoid leprosy either secreted interleukin 1 spontaneously or produced amounts within the normal range in response to lipopolysaccharide stimulation. Conversely, stimulated cells from lepromatous patients failed to produce interleukin 1 in 5 of 13 (38.5%) cases.     

Resveratrol suppresses interferon-gamma-induced biochemical pathways in human peripheral blood mononuclear cells in vitro

A wide range of biological activities of resveratrol (3,5,4′-trihydroxystilbene) in vitro and in vivo has been proved, including antioxidant, antitumor, and also anti-inflammatory effects. Resveratrol found in, e.g., grapes and red wine has been suggested to counteract the progression of coronary heart disease by lowering serum lipid concentrations and inhibiting platelet aggregation. Cellular immune activation is known to be involved crucially in the pathogenesis of coronary heart diseases. In this in vitro study, the modulatory effect of resveratrol on two interferon-γ-mediated pathways, the degradation of tryptophan by the enzyme indoleamine 2,3-dioxygenase, and the production of neopterin by activation of the GTP-cyclohydrolase I, was tested. Cultures of human peripheral blood mononuclear cells were exposed to resveratrol, in combination with mitogenic stimulation. A significant down-regulatory effect of resveratrol on both biochemical pathways was found, and also the production of Th1-type cytokine interferon-γ was significantly suppressed. If these results can be verified in vivo, an explanation is provided how resveratrol may interfere with immune activation and cytokine cascades, which are important in the development and progression of cardiovascular disorders and also other diseases.     

MHC-unrestricted lysis of MUC1-expressing cells by human peripheral blood mononuclear cells

Many human adenocarcinomas can be killed in vitro by targeted cytotoxic T-lymphocytes (CTL); however, major histocompatibility complex (MHC)-restrictions are typically required. The MUC1 antigen is common in many human adenocarcinomas, and is associated with a variable number of tandem repeats. It has been proposed that antigens with such repeated epitopes may be vulnerable to cytotoxic T-lymphocyte killing without MHC-restriction. Therefore, it is possible that MUC1-expressing malignant cells may be killed by targeted cytotoxic T-lymphocyte in the absence of MHC-restriction. In this study, a human MUC1-expressing murine mammary carcinoma cell line was used to determine if cytotoxic T-lymphocyte killing of MUC1-expressing adenocarcinoma cells requires MHC-restriction. Specifically, MUC1-stimulated human mononuclear cells (M1SMC) were observed to kill human MUC1-transfected, MUC1-expressing murine mammary carcinoma cells, but not the mock-transfected, non-MUC1-expressing murine mammary carcinoma cells. Furthermore, the killing was blocked by antibody to MUC1, indicating MUC1-specific killing. In conclusion, cytotoxic T-lymphocyte killing of MUC1-expressing adenocarcinoma cells can be MHC-unrestricted.     

The effect of random blood transfusions on immunoglobulin production by peripheral blood mononuclear cells from uraemic patients.

The effect of blood transfusion on humoral immunity in chronic renal failure was studied by examining immunoglobulin production in vitro, in patients awaiting renal transplantation. Pokeweed mitogen (PWM) induced IgG plaque formation was normal in non-transfused uraemic patients while both spontaneous and Staphylococcus aureus Cowan I (SAC) induced immunoglobulin production were reduced. Five to ten units of third party blood transfusion reduced PWM-driven B cell differentiation, but had no effect on SAC-induced plaque formation, while spontaneous production of immunoglobulin was either enhanced or unaffected. As it is known that the response to SAC is less affected by suppressor T cell activity than that to PWM, these differences in the inhibitory effects of blood transfusion on B cell differentiation are further evidence that transfusion may act by increasing suppressor T cell activity.     

Simvastatin induces interleukin-18 production in human peripheral blood mononuclear cells

The effects of statins on immune response depend on the inhibition of 3-hydroxy-3-methylglutaryl coenzyme-A (HMG-CoA) reductase and leukocyte function-associated antigen (LFA)-1, which is a ligand of intercellular adhesion molecule (ICAM)-1. Simvastatin, an HMG-CoA reductase inhibitor with mild inhibition of LFA-1, induced the production of interleukin (IL)-18, tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma in human peripheral blood mononuclear cells (PBMC). The IL-18 production is located upstream of the cytokine cascade activated by simvastatin. Moreover, simvastatin concentration-dependently inhibited the expression of ICAM-1 and induced the expression of CD40 on monocytes. In the presence of IL-18, simvastatin suppressed the expression of ICAM-1 and CD40 as well as the production of IL-12, TNF-alpha and IFN-gamma in PBMC, contributing to the anti-inflammatory effect of simvastatin. The effects of simvastatin were abolished by the addition of the product of the HMG-CoA reductase, mevalonate, indicating the involvement of HMG-CoA reductase in the action of simvastatin.     

Cytokine production by human milk cells and peripheral blood mononuclear cells from the same mothers

Samples of milk (n = 80) and venous blood were collected at 5 weeks postpartum from 82 lactating mothers. Human milk cells and peripheral blood mononuclear cells were isolated and the production of interleukin-1, interleukin-6, and tumor necrosis factor- in the absence and presence of lipopolysaccharide was determined by enzyme-linked immunosorbent assay. Human milk cells spontaneously produced significantly less interleukin-1, interleukin-6, and tumor necrosis factor- than peripheral blood mononuclear cells in the absence of stimulation. In vitro stimulation of human milk cells with lipopolysaccharide (500 ng/ml) for 24 hr increased cytokine production by approximately 40–50%, whereas peripheral blood mononuclear cells responded to lipopolysaccharide (200 ng/ml) with increased cytokine production of up to 350%. These observations suggest that cells in milk are capable of active involvement in the production of the interleukin-1, interleukin-6, and tumor necrosis factor- in the mammary gland and have the capacity to respond to further stimulation after leaving the breast.     

Cytokine production by peripheral blood mononuclear cells following birch-pollen immunotherapy

We studied the Th2/Th1 balance by short-term stimulation of peripheral blood mononuclear cells (PBMC) isolated during the pollen season from seven allergic patients treated with conventional birch-pollen immunotherapy (IT) for 18 months, eight matched allergic control patients and 10 non-atopic individuals. The PBMC were cultured for 7 days with birch-pollen extract (BPE) or tetanus toxoid (TT), and then restimulated with PHA and PMA to induce high IL-5, IL-10 and IFN-gamma production. The serum levels of birch-pollen-specific IgG and IgG4 were significantly elevated after IT treatment. The proliferative response to BPE was significantly enhanced in the allergic control group, but not in the IT-treated group, compared to the non-atopic group (P<0.05). Birch-pollen-specific IL-5 production was significantly enhanced in both the IT-treated group and the allergic control group (P<0.01-0. 05). Furthermore, both the IT-treated group and the allergic control group had a cytokine profile to BPE significantly more Th2 polarized (high IL-5/IFN-gamma ratio) than to TT (P<0.05 and P<0.01, respectively). No differences in IL-10 production between the three study groups were observed. The Th2/Th1 balance in vitro correlated with the serum concentrations of birch-pollen-specific IgE (r=0.60, P<0.05), and in the IT-treated group, also with the IgG and IgG4 levels (r=0.79, P<0.05 and r=0.86, P<0.05, respectively). We conclude that conventional birch-pollen IT does not lead to changes in the cytokine profile of the circulating pool of allergen-specific T cells during birch-pollen season. However, induction of peripheral T-cell tolerance and increased production of specific IgG and IgG4 might be part of the mechanisms of IT.     

Chemokine production by peripheral blood mononuclear cells in elderly subjects

The function of chemokines in promoting and modulating leukocyte migration is essential for a prompt and efficacious inflammatory response and in host defence against infections. In order to investigate whether this important aspect of immunological response is influenced by ageing, we evaluated the basal levels as well as the ability of peripheral blood mononuclear cells from young and healthy elderly subjects to produce chemokines (IL-8, MCP-1, MIP-Iα, RANTES) in response to stimulation with anti-CD3 monoclonal antibody and lipopolysaccharide (LPS), a gram negative bacterial endotoxin. Our main findings are a spontaneous chemokine production; a 20% decrease of proliferative response to anti-CD3 monoclonal antibody accompanied by an age related increase of MIP-Iα and RANTES production and by a general increase of all chemokine production compared to unstimulated conditions; a proliferative defect of monocytes to LPS challenge associated with an increase of chemokine production compared to basal conditions with a progressive age-related increase of MIP-lα. In conclusion, this study suggests that chemokines could have a compensatory role in balancing the impaired mechanisms involved in ‘specific’ immune response during ageing. The successful activation of this strategy could contribute to the good performance of immune system so maintaining healthy status in elderly.     

Chemokine production by peripheral blood mononuclear cells in elderly subjects

The function of chemokines in promoting and modulating leukocyte migration is essential for a prompt and efficacious inflammatory response and in host defence against infections. In order to investigate whether this important aspect of immunological response is influenced by ageing, we evaluated the basal levels as well as the ability of peripheral blood mononuclear cells from young and healthy elderly subjects to produce chemokines (IL-8, MCP-1, MIP-Ialpha, RANTES) in response to stimulation with anti-CD3 monoclonal antibody and lipopolysaccharide (LPS), a gram negative bacterial endotoxin. Our main findings are a spontaneous chemokine production; a 20% decrease of proliferative response to anti-CD3 monoclonal antibody accompanied by an age related increase of MIP-Ialpha and RANTES production and by a general increase of all chemokine production compared to unstimulated conditions; a proliferative defect of monocytes to LPS challenge associated with an increase of chemokine production compared to basal conditions with a progressive age-related increase of MIP-lalpha. In conclusion, this study suggests that chemokines could have a compensatory role in balancing the impaired mechanisms involved in 'specific' immune response during ageing. The successful activation of this strategy could contribute to the good performance of immune system so maintaining healthy status in elderly.     

Nigerooligosaccharides augments mitogen-induced proliferation and suppresses activation-induced apoptosis of human peripheral blood mononuclear cells

Nigerooligosaccharides (NOS), a mixture of nigerose and nigerosylmaltooligosaccharides, consists of immunopotentiating oligosaccharides found in foodstuffs. We have previously reported that activation of peripheral blood mononuclear cells (PBMC) in response to concanavalin A (Con A) or a streptococcal preparation of OK-432 is augmented in healthy young adults and elderly subjects after the intake of NOS-supplemented syrup. A reappraisal of the data suggests that NOS augments proliferation but partly suppresses activation-induced apoptosis of PBMC in response to these mitogens. To confirm this hypothesis, PBMC from healthy male subjects were stimulated with Con A or OK-432 in the presence of nigerose at the concentrations at which it was detected in the blood of subjects who had ingested NOS-supplemented syrup. Cellular activation, specifically metabolic demand, viability and proliferation, was assessed from glucose consumption, by WST-1 colorimetry and by 5-bromo-2'-deoxy-uridine incorporation assay, respectively. The Con A-induced activation of PBMC in each measurement was significantly augmented by nigerose. OK-432-induced decreases in the viability of PBMC were significantly inhibited by nigerose. Stimulation of PBMC with Con A or OK-432 induced apoptosis, but nigerose suppressed such activation-induced cell death. These results indicated that nigerose activated PBMC in vitro in a manner similar to the process observed in vivo, providing further evidence for the effectiveness of consumption of NOS-supplemented syrup.     

Concanavalin-A displays leishmanicidal activity by inducing ROS production in human peripheral blood mononuclear cells

Abstract

The context of the article: Leishmania amazonensis has a wide geographical distribution throughout South American countries and can cause self-healing to severe cases as mucocutaneous or visceral forms. Leishmaniasis presents a balance of inflammatory and anti-inflammatory cytokines which is responsible for promoting the activation of phagocytes, essential to control the infection and lead to tissue repair/resolution of the disease, respectively.

Results and discussion: Our model revealed that the treatment with Con-A was capable to stimulate human PBMC cells by increasing the phagocytic capacity and promoting parasite elimination. The pretreatment with Con-A promoted inflammatory (IFN-γ, TNF-α, IL-2 and IL-6) and anti-inflammatory (IL-4 and IL-10) cytokines production, increased the reactive oxygen species (ROS) sinthesys as well as the expression and presence of iNOS enzyme, but not nitric oxide production.

Conclusion: Based on the data obtained, it was possible to infer that Con-A induces the ROS production, responsible for eliminating parasites in addition to regulatory cytokines synthesis which are important for disease resolution.     

Modulation of in vitro immunoglobulin synthesis of human peripheral blood mononuclear cells by nicotine and cotinine

The influence of nicotine and its main metabolite cotinine on the spontaneous and cytokine-induced immunoglobulin synthesis was studied. The immunoglobulin (G,A) synthesis of peripheral blood mononuclear cells was altered by nicotine donor dependently in the concentration range from 10–6 to 10^–8 M. Cotinine also modulates immunoglobulin (G, A) synthesis. The effective concentration range is about 100 fold higher. Only marginal effects on IgM synthesis were observed. Neither nicotine nor cotinine showed any effect on IgE production or on the IgE class switch. Moreover, both agents induced the production of the cytokines interleukin-1, –2, –3, –4, and –6. Therefore it is suggested that the strongly donor-dependent heterogeneity in the response to nicotine or cotinine is the result of the fine balance of theinduced cytokines.Abbreviations IFN interferon - IL interleukin - PBMC peripheral blood mononuclear cells - TNF tumor necrosis factor Correspondence to: A. Fischer     

In vitro effect of lycopene on cytokine production by human peripheral blood mononuclear cells

There is evidence indicating that regular consumption of tomato products is associated with favorable immunomodulatory effects. In addition, tomato extracts have been shown to possess antioxidant, anticarcinogenic and antithrombotic activity in vitro. Since tomatoes are rich in carotenoids and particularly in lycopene--the pigment responsible for the red color of tomatoes--the present work was designed to examine the in vitro effect of lycopene on cytokine production by peripheral blood mononuclear cells (PBMC) from 15 healthy subjects. First, 2 x 10(6) PBMC suspended in 1 ml of conditioned medium were incubated over a period of 24 and 48 hours without or with the following concentrations of lycopene: 0.25, 0.5, 1.0, 2.0 and 4.0 microM. The production of the subsequent cytokines was evaluated: IL-1beta, IL-1ra, IL-2, IL-6 and IL-10, as well as TNFalpha and IFNgamma. Lycopene induced a dose-dependent increase in IL1beta, and TNFalpha production and a decrease in IL-2, IL-10 and IFNgamma secretion, whereas that of IL-6 and IL-1ra was not affected. It is concluded that understanding the role of lycopene in modulation of the immune system may promote decisions as for dietary supplementation of lycopene for reducing the risk of certain diseases.