PHA-stimulated Peripheral Blood Mononuclear Cells Research Articles

Isolation of stem cell populations with trophic and immunoregulatory functions from human intestinal tissues: potential for cell therapy in inflammatory bowel disease

Bone marrow (BM)- and adipose tissue (AT)-derived mesenchymal stromal cells (MSC) are currently under evaluation in phase III clinical trials for inflammatory bowel disease and other intestinal disease manifestations. The therapeutic efficacy of these treatments may derive from a combination of the differentiation, trophic and immunomodulatory abilities of the transplanted cells. We investigated intestinal tissues as sources of MSC: such cells may support tissue-specific functions and hold advantages for engraftment and contribution in the gastrointestinal environment. Intestinal specimens were collected, and the mucosa and submucosa mechanically separated and enzymatically digested. Mesenchymal stromal populations were isolated, expanded and characterized under conditions commonly used for MSC. The differentiation potential, trophic effect and immunomodulatory ability were investigated. Results We successfully isolated and extensively expanded populations showing the typical MSC profile: CD29+, CD44+, CD73+, CD105+ and CD166+, and CD14(-), CD34(-) and CD45(-). Intestinal mucosal (IM) MSC were also CD117+, while submucosal cultures (ISM MSC) showed CD34+ subsets. The cells differentiated toward osteogenic, adipogenic and angiogenic commitments. Intestinal-derived MSC were able to induce differentiation and organization of intestinal epithelial cells (Caco-2) in three-dimensional collagen cultures. Immunomodulatory activity was evidenced in co-cultures with normal heterologous phytohemagglutinin-stimulated peripheral blood mononuclear cells. Conclusions Multipotent MSC can be isolated from intestinal mucosal and submucosal tissues. IM MSC and ISM MSC are able to perform trophic and immunomodulatory functions. These findings could open a pathway for novel approaches to intestinal disease treatment.

The immunosuppressive drug thalidomide induces T helper cell type 2 (Th2) and concomitantly inhibits Th1 cytokine production in mitogen- and antigen-stimulated human peripheral blood mononuclear cell cultures.

Thalidomide is an effective immunomodulatory drug in man, but its mechanism of action remains unclear. We hypothesized that, in addition to its reported inhibitory effects on production of monocyte-derived tumour necrosis factor-alpha (TNF-alpha), thalidomide might be effective at the level of Th immunoregulation. In a comparative study with the immunosuppressant cyclosporin A, we have demonstrated a potent and specific effect of thalidomide on cytokine production relating to the distinct Th1 and Th2 subsets. It induced and enhanced the production of IL-4 and IL-5 and, at the same dose (1000 ng/ml), significantly inhibited interferon-gamma (IFN-gamma) production in phytohaemagglutinin (PHA)-stimulated human peripheral blood mononuclear cell (PBMC) cultures. Stimulation of PBMC with recall antigen (streptokinase:streptodornase (SKSD)) at 144 h in the absence of thalidomide resulted in a predominantly Th1 response, with the production of IFN-gamma and IL-2. Thalidomide switched this response from a Th1 to a Th2 type. The effect was most pronounced at 1000 ng/ml thalidomide, where inhibition of IFN-gamma and enhancement of IL-4 production was maximal. In unstimulated cultures thalidomide alone induced IL-4 production. Cyclosporin A, in contrast, inhibited both Th1 and Th2 cytokine production by PHA-stimulated PBMC. Time course data from thalidomide-treated cultures revealed that the augmented IL-4 production diminished as the culture time increased, whereas IFN-gamma production was significantly increased. This response might be due to activation-induced apoptosis of Th2 cells or the induction of Th2 cell anergy, in the continued presence of stimulating agents, with the emergence of IFN-gamma-secreting Th1 cells when Th2 antagonism declines. The effects of thalidomide and related compounds may enhance our understanding of the mechanisms of T helper cell selection, offer the possibility of controlled therapeutic switching between Th1 and Th2 responses, and may lead to a rational approach for the treatment of some T cell-mediated immunological disorders.

Abnormal production of B cell growth factor in patients with systemic lupus erythematosus.

In order to clarify the role of B cell growth factor (BCGF) in the pathogenesis of systemic lupus erythematosus (SLE), BCGF production by peripheral blood mononuclear cells (PBMC) and T cells was studied using a new bioassay for BCGF activity. For this purpose, we established an Epstein-Barr (EB) virus-transformed B cell line KS-3.F10 that proliferates only in response to two B cell-specific BCGF, low-mol. wt BCGF (LMW-BCGF) and high-mol. wt BCGF (HMW-BCGF). PBMC from active SLE patients produced less BCGF when stimulated with phytohaemagglutinin (PHA) compared with controls. The decreased BCGF production by PHA-stimulated PBMC from active SLE reverted to control values when SLE became inactive. However, PHA-stimulated T cells from active SLE patients produced more BCGF compared with controls, whereas those from inactive SLE showed normal BCGF production. Spontaneous BCGF production by T cells was not observed in active SLE patients. These findings suggest that decreased BCGF production by SLE PBMC is due to excessive BCGF consumption by B cells in vitro and that SLE T cells produce large amounts of BCGF with appropriate immune stimuli in vivo to promote polyclonal B cell activation.

Increased IL-6 gene expression and production in patients with common variable immunodeficiency.

We have studied IL-6 gene expression and production by in vitro stimulated peripheral blood mononuclear cells (PBMC) isolated from common variable immunodeficiency (CVI) patients. A strong hybridization signal for the IL-6 probe was observed in mRNA extracted from phytohaemagglutinin (PHA)- and PHA/phorbol myristate acetate (PMA)-stimulated PBMC from most of 12 CVI patients analysed. IL-6 production by PHA-stimulated PBMC from 28 CVI patients was evaluated in ELISA and found to be significantly (P < 0.0001) higher than in normal controls. IL-6 production, however, did not correlate with the lymphocyte populations examined, nor with the absolute number of monocytes. We have also showed that IL-6 was able to increase IgM secretion by several Epstein-Barr virus (EBV)-transformed cell lines derived from both normal donors and CVI patients, but it failed to modify substantially the amounts of IgM and IgG produced in vitro by PBMC derived from CVI patients and activated with pokeweed mitogen (PWM) or anti-IgM. Our data indicate that IL-6 gene expression and production is increased in CVI, but CVI cells do not respond to IL-6 with increased production of immunoglobulin.

Interleukin-2, interleukin-12, and interferon-γ levels and risk of young adult Hodgkin lymphoma

AbstractYoung adult Hodgkin lymphoma (YAHL) is associated clinically with altered immunity, including a systemic defect in cell-mediated responses. There is strong evidence of a genetic contribution to risk, so we hypothesized that heritable alterations in cytokine production associated with Th1 function may contribute to susceptibility. We identified twin pairs in whom at least one member had YAHL and measured interleukin-2 (IL-2), interleukin-12 (IL-12), and interferon-γ (IFN-γ) levels in PHA-stimulated peripheral blood mononuclear cell supernatant in 90 case-twins, 84 of their disease-free twins (unaffected cotwins), and 90 matched controls. Mean difference and mean percentage difference in cytokine levels between case-twins and controls, and unaffected cotwins and controls were determined using analysis of covariance. YAHL case-twins and their unaffected cotwins had IL-12 levels that were 60.6% (P = .002) and 49% (P = .04) lower than those of their matched controls, respectively. IL-2 levels were significantly higher in case-twins (P = .049), but not unaffected cotwins (P = .57), compared with controls. Differences in IFN-γ levels were not statistically significant in either comparison. An IL-12 polymorphism known to regulate expression was associated with a 2.8-fold (P = .03) increase in YAHL risk. Thus, both case-twins and their unaffected cotwins had a decreased ability to produce IL-12, which may contribute to YAHL susceptibility.

Molecular cloning and functional analysis of goose interferon gamma

The cDNA for goose interferon gamma (goIFN-γ) was cloned from PHA-stimulated goose peripheral blood mononuclear cells (PBMCs) by RT-PCR. This cDNA encodes a 19-amino acid signal peptide and a 145-amino acid mature protein, which shares a high homology with duck IFN-γ. Recombinant mature goose interferon gamma (rgoIFN-γ) generated from both prokaryotic and eukaryotic expression systems effectively inhibited the replication of goose paramyxovirus and recombinant vesicular stomatitis virus in vitro. These antiviral activities were abrogated by rabbit anti-rgoIFN-γ antibodies in vitro. Furthermore, rgoIFN-γ stimulated goose peritoneal macrophages to produce nitric oxide (NO) in vitro, demonstrating its macrophage activating factor (MAF) activity. Therefore, the availability of bioactive rgoIFN-γ and its specific antibodies provides valuable tools for studying T cell immunity in geese

Anti-inflammatory effect of Sasim extracts in PHA-stimulated THP-1 and peripheral blood mononuclear cells from cerebral infarction patients

Sasim, a prescription composed of seven herbal mixtures, has been widely used for the treatment of cerebral infarction as an oriental medicine in Korea. However, the mechanisms by which the formula affects on the production of pro-inflammatory cytokines in cerebral infarct patients remain unknown yet. The levels of secretory protein and mRNA of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α, interlukin (IL)-1β, and IL-6, were significantly increased in both THP-1 differentiated macrophage-like cells (T/M) and peripheral blood mononuclear cells (PBMCs) from cerebral infarct patients at 24 h after stimulation with phytohemagglutinin (PHA) ( p < 0.05). However, pretreatment of Sasim strongly suppressed the secretion of pro-inflammatory cytokines in PHA-stimulated T/M cells and PBMCs. Moreover, Sasim significantly suppressed the transcriptional levels of pro-inflammatory cytokines in PHA-stimulated THP-1/M cells. These data indicate that Sasim may be beneficial in the cessation of inflammatory processes of cerebral infarction through suppression on the production of pro-inflammatory cytokines via inhibition of mRNA expression.

Anti-inflammatory Effect of Oyaksungisan in Peripheral Blood Mononuclear Cells from Cerebral Infarction Patients

Oyaksungisan, the herbal prescription composed of eleven herbs, has been widely used in treatment of cerebral infarct in Oriental Medicine. However, the mechanisms by which the herbal formula affects on the production of pro- and anti-inflammatory cytokines in cerebral infarction patients remain unknown yet. The secretory levels of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6, and IL-10 were significantly increased in both LPS and PHA-stimulated peripheral blood mononuclear cells (PBMCs) from cerebral infarction patients. However, pretreatment with oyaksungisan significantly inhibited the secretion of pro- and anti-inflammatory in PBMCs. Also, oyaksungisan induced a significant increase of transforming growth factor (TGF)-beta1 in PBMCs. Thus, these data indicate that oyaksungisan may be beneficial in the cessation of inflammatory processes of cerebral infarct through suppression of TNF-alpha, IL-1beta, IL-6, and IL-10 and induction of TGF-beta1.

REISHI AND POLYSACCHARIDE-KRESTIN AS IMMUNE MODULATORS: DIFFERENTIAL EFFECTS OF MUSHROOM EXTRACTS ON BOTH CYTOKINE SECRETION AND INDUCTION OF T REGULTORY CELLS FROM HUMAN PERIPHERAL BLOOD.

A Reishi mushroom extract (Ganoderma lucidum) and polysaccharide-krestin (PSK, a well-studied extract of the mushroom Trametes versicolor) have been used in traditional Chinese medicine to treat various diseases by modifying immune functions. We investigated the immune response to these mushroom extracts in human blood cells. Human peripheral blood mononuclear cells (PBMCs) were isolated from whole blood, either left unstimulated or stimulated with phytohemagluttinin (PHA), and either left untreated or treated with extracts of Reishi and PSK. Cytokine levels in the cell supernatants were measured using ELISA. The PSK-treated cells had increased TNF-α, IFN-γ, and IL-4 secretion compared with control. Reishi extract-treated PBMCs had decreased TNF-α and IFN-γ secretion and IL-4 production. These results led us to test for the differential induction or suppression of regulatory T cells (Tregs) by these extracts. Human PBMCs left unstimulated or stimulated with PHA and either untreated or treated with Reishi extract and PSK were stained with anti-CD4, anti-CD25, and anti-Foxp3 antibodies. The cells were analyzed using flow cytometry, and the percentage of CD4+/CD25+/Foxp3+ cells was measured. Reishi alone enhances CD4+/CD25+/Foxp3+ cell populations (Tregs). PSK alone did not significantly enhance Tregs but did enhance Tregs in PHA-stimulated PBMCs, but to a lesser extent than the Reishi extract. Further research is needed to determine the mechanisms of Treg induction and to examine the in vivo role of these extracts in cancer and autoimmunity.

Changes in telomerase activity after irradiation of human peripheral blood mononuclear cells (PBMC) in vitro

Telomerase activity (TA) has been shown to be up-regulated by ionising radiation in immortal hematopoietic cell lines. The purpose of the present experiments was to test whether ionising radiation may regulate TA in normal human peripheral blood mononuclear cells (PBMC). A real-time PCR assay was established to quantify TA detected by the telomeric repeat amplification protocol. TA of PBMCs isolated from young healthy donors was highly increased by stimulation with phytohemagglutinin (PHA) for 72 h. Irradiation of PHA-stimulated PBMCs with 2-10 Gy of X rays showed up-regulated TA 4 h after irradiation with an enhancement at least as strong as for the human TK6 lymphoblastoid cell line. The present results show that TA is up-regulated by irradiation not only in immortal cell lines but also in mitogen-stimulated PBMCs. This supports a possible role for telomerase in the cellular radiation response.

The major population of PHA-stimulated PBMC infected by R5 or X4 HIV variants after a single cycle of infection is predominantly composed of CD45RO+CD4+ T lymphocytes

PHA-stimulated peripheral blood mononuclear cells (PBMCs) are widely used for investigating replication and neutralization of HIV primary isolates in vitro. The objective of this study was to identify the T lymphocyte subset(s) that are found infected after one replication cycle by either R5- or X4-HIV-1 variants in PHA-stimulated PBMCs from healthy donors. Infected T lymphocytes were detected by intracellular p24 staining and characterized by cell surface immunophenotyping using flow cytometry. The predominant lymphocyte subset expressing p24 after 24 h of infection with either R5 or X4 HIV-1 strains was found to exhibit mainly the memory CD45RO phenotype, a greater percentage of CD62L(+)CD45RO(+) central memory T lymphocytes was infected with X4 HIV strains. Although some CD45RA(+) lymphocytes were also infected, these cells co-expressed CD45RO(+). The proportion of lymphocytes expressing CD4 and CD4/CD45RO decreased by 20% after 24 h of infection. A 2-fold decrease of CD4(+)CD8(+) T lymphocytes could also be recorded, even though this subset accounted for less than 5% of total lymphocytes in control cultures. Moreover, CD4(+)CD8(+) T cells further decreased by 90% after 4 days of infection, a time at which they scored p24(+). Therefore, our results indicate that the in vitro infection system of PHA-stimulated PBMC utilized in neutralization assays provides an appropriate model for the study of infected CD45RO(+) lymphocytes but not CD45RA(+) lymphocytes.

Impaired cytokine production and suppressed lymphocyte proliferation activity in HCV-infected cocaine and heroin (“speedball”) users

HCV-infected “speedball” users ( n = 30) were selected from an original cohort of 400 intravenous drug users for cytokine analysis. Cytokine concentrations (TNF-α, IL-1β, IL-6, IFN-γ, IL-2, IL-4, IL-10 and IL-12) were determined in plasma and peripheral blood mononuclear cells (PBMC) cultures derived ex vivo from these patients. In addition, lymphocyte proliferation was measured in 49 HCV-positive “speedball” users. TNF-α, IL-6, IFN-γ, IL-2, IL-4, IL-10, IL-12 cytokines and not IL-1β were significantly increased in plasma from HCV-positive “speedball” users compared with healthy controls. Except for IL-10, all other cytokines measured were augmented in phytohemagglutinin-stimulated PBMC cultures from HCV-positive “speedball” users. Likewise, overproduction of cytokines TNF-α, IL-1β, IL-6 and IFN-γ, was consistently detected when PBMC cultures from HCV-positive “speedball” users were stimulated with a biological response modifier. However, HCV-infected “speedball” users showed significant reduction in lymphoproliferative activity. Compared with healthy subjects, there was a consistent overproduction of both TH1 and TH2 type cytokines in the plasma and PBMC's of HCV-infected “speedball” users. Furthermore, there was a persistent reduction of lymphoproliferative activity in this group. These immunologic abnormalities, coupled with the range of response between the two TH-types in HCV-infected “speedball” users, suggest impairment in the regulatory mechanism of the TH1–TH2 system.

Nonneutralizing Antibodies Are Able To Inhibit Human Immunodeficiency Virus Type 1 Replication in Macrophages and Immature Dendritic Cells

Only five monoclonal antibodies (MAbs) neutralizing a broad range of primary isolates (PI) have been identified up to now. We have found that some MAbs with no neutralizing activities according to the "conventional" neutralization assay, involving phytohemagglutinin-stimulated peripheral blood mononuclear cells as targets, efficiently inhibit the replication of human immunodeficiency virus type 1 (HIV-1) PI in macrophages and immature dendritic cells (iDC). The mechanism of inhibition is distinct from the neutralization of infectivity occurring via Fab fragments and involves the interaction of the F portion with the FcgammaRs present on macrophages and iDC. We propose that, if such nonneutralizing inhibitory antibodies limit mucosal HIV transmission, they should be induced by vaccination.

Methotrexate enhances the anti-inflammatory effect of CF101 via up-regulation of the A3 adenosine receptor expression

Methotrexate (MTX) exerts an anti-inflammatory effect via its metabolite adenosine, which activates adenosine receptors. The A3 adenosine receptor (A3AR) was found to be highly expressed in inflammatory tissues and peripheral blood mononuclear cells (PBMCs) of rats with adjuvant-induced arthritis (AIA). CF101 (IB-MECA), an A3AR agonist, was previously found to inhibit the clinical and pathological manifestations of AIA. The aim of the present study was to examine the effect of MTX on A3AR expression level and the efficacy of combined treatment with CF101 and MTX in AIA rats. AIA rats were treated with MTX, CF101, or both agents combined. A3AR mRNA, protein expression and exhibition were tested in paw and PBMC extracts from AIA rats utilizing immunohistochemistry staining, RT-PCR and Western blot analysis. A3AR level was tested in PBMC extracts from patients chronically treated with MTX and healthy individuals. The effect of CF101, MTX and combined treatment on A3AR expression level was also tested in PHA-stimulated PBMCs from healthy individuals and from MTX-treated patients with rheumatoid arthritis (RA). Combined treatment with CF101 and MTX resulted in an additive anti-inflammatory effect in AIA rats. MTX induced A2AAR and A3AR over-expression in paw cells from treated animals. Moreover, increased A3AR expression level was detected in PBMCs from MTX-treated RA patients compared with cells from healthy individuals. MTX also increased the protein expression level of PHA-stimulated PBMCs from healthy individuals. The increase in A3AR level was counteracted in vitro by adenosine deaminase and mimicked in vivo by dipyridamole, demonstrating that receptor over-expression was mediated by adenosine. In conclusion, the data presented here indicate that MTX induces increased A3AR expression and exhibition, thereby potentiating the inhibitory effect of CF101 and supporting combined use of these drugs to treat RA.

Identification of strong interleukin‐10 inducing lactic acid bacteria which down‐regulate T helper type 2 cytokines

Decreased exposure to microbial stimuli has been proposed to be involved in the increased prevalence of atopic disease. Such a relationship was indicated by enhanced presence of typical probiotic bacteria in the intestinal flora correlating with reduced prevalence of atopic disease. Recent clinical trials suggested that probiotic bacteria may decrease and prevent allergic symptoms, but which (different) species or strains may contribute is poorly understood. We sought to select probiotic bacteria by their ability to modulate in vitro production of cytokines by peripheral blood mononuclear cells (PBMCs), to make a rational choice from available strains. PBMCs, purified monocytes, and lymphocytes from healthy donors were co-cultured with 13 different strains of probiotic bacteria. The effect of lactic acid bacteria (LAB) on different cell populations and effects on cytokine production induced by the polyclonal T cell stimulator phytohaemagglutinin (PHA) was evaluated by measuring T helper type 1, T helper type 2 (Th2), and regulatory cell cytokines in culture supernatants by multiplex assay. PBMCs cultured with different strains produced large amounts of IL-10 and low levels of IL-12p70, IL-5, and IL-13. In PHA-stimulated PBMC cultures, the tested strains decreased the production of Th2 cytokines. Neutralizing IL-10 production resulted in partial to full restoration of Th2 cytokine production and concurred with an increase in pro-inflammatory cytokines such as IL-12p70 and TNF-alpha. Within the PBMCs, the CD14(+) cell fraction was the main source of IL-10 production upon interaction with LAB. Our results indicate that certain strains of lactobacilli and bifidobacteria modulate the production of cytokines by monocytes and lymphocytes, and may divert the immune system in a regulatory or tolerant mode. These specific strains may be favorable to use in prevention or treatment of atopic disease.

Replication of TT virus in hepatocyte and leucocyte cell lines

The TT virus (TTV) is a non-enveloped, single-stranded, circular, DNA virus, first isolated from a patient with hepatitis of unexplained etiology. The much deliberated pathological role of the virus continues to be conjectural in the absence of a suitable in vitro replication model. So far, the liver and the bone marrow have been shown to be the main sites of TTV replication. In this study, the human cell lines HepG2 and Chang Liver, the rat hepatoma cell line MH1C1, phytohemagglutinin (PHA)-stimulated TTV-negative peripheral blood mononuclear cell (PBMC) cultures and the B lymphoblast cell line, Raji were investigated as potential in vitro replication systems for TTV. The cell lines were infected with an inoculum prepared by pooling TTV genotype1 DNA positive sera and monitored for virus replication. Of the three hepatocyte cell lines, while the HepG2 and MH1C1 cell lines did not support TTV replication, the Chang Liver cell line showed clear morphological changes as a result of the in vitro infection, which included clumping and granular degeneration of the entire cell sheet over a period of 6 days. The infected cells also showed presence of virus-specific mRNA representative of viral transcription. The consistent presence of infectious viral particles in the supernatant culture fluid at 24-hr fluid replacement intervals indicated limited extra-cellular release of viral particles. The PHA-stimulated TTV-negative PBMC cultures and the Raji cell line were also able to support TTV replication and released significant levels of infectious viral particles into the supernantant culture fluid.

Cytokine induction of interleukin-24 in human peripheral blood mononuclear cells

Interleukin-24 (IL-24) is a recently identified member of the IL-10 family of cytokines. It was originally identified as a tumor suppressor molecule, melanoma differentiation-associated gene 7, and then renamed IL-24 and classified as a cytokine, based on its chromosomal location in the IL-10 locus, its mRNA expression in leukocytes, and its secretory sequence elements. Here, we correlate the kinetics of IL-24 mRNA and protein expression in human peripheral blood mononuclear cells (PBMC) stimulated by polyclonal activators phytohemagglutinin (PHA) and lipopolysaccharide (LPS) or by allogeneic major histocompatibility complex. PHA-stimulated PBMC express IL-24 mRNA, reaching peak levels at 8-12 h after stimulation. Protein expression, as measured by intracellular flow cytometry, followed the message, reaching maximum expression at 24 h. Subset analysis of mitogen-stimulated PBMC showed that IL-24 was expressed primarily in T cells and macrophages. Expression of IL-24 in mitogen-stimulated PBMC is the result of cytokine stimulation. Individual cytokines including IL-2, IL-7, IL-15, tumor necrosis factor alpha, granulocyte macrophage-colony stimulating factor, and IL-1beta stimulate the expression of IL-24 mRNA and protein, whereas interferons and T helper cell type 2 cytokines fail to induce substantial IL-24. When LPS- or PHA-stimulated cells were treated with Actinomycin D, IL-24 mRNA persisted at high levels over the 4-h course of treatment. These data strongly suggest that the expression of IL-24 in human PBMC results from cytokine stimulation and is regulated at the post-transcriptional level through stabilization of IL-24 mRNA.

Beta2-Adrenergic Receptors Mediate the Differential Effects of Catecholamines on Cytokine Production of PBMC

We determined characteristics of beta2-adrenergic receptors (beta2R) on peripheral blood mononuclear cells (PBMC) and cytokine production after mitogenic stimulation and coincubation with catecholamines. PBMCs were stimulated with interleukin-2 (IL-2), tetanus toxoid (TT), anti-CD3 antibody, or phytohemagglutinin (PHA). The cytokines interferon-gamma (IFN-gamma), IL-4, and IL-6 were determined by ELISA following coincubation with high-dose (10(-5) M) and low-dose (10(-9) M) epinephrine (EPI) and norepinephrine (NE). Intracellular IFN-gamma and IL-4 were studied by FACS analysis. The beta2R density was investigated using a radioligand binding assay. The stimuli induced various cytokine profiles in PBMCs. Synthesis of IFN-gamma was induced by all mitogens and could be suppressed by catecholamines (26%-85% reduction). In PHA-stimulated PBMCs, IL-4 synthesis was decreased by high-dose catecholamines (24%-28% reduction). Adding a beta-blocking agent attenuated most catecholamine effects. A highly significant negative correlation between the density of beta2R with IFN-gamma and IL-6 levels of PHA-activated PBMCs (r = -0.88 to -0.96, p < 0.01-< 0.001) was observed. The results indicate that the density of beta2R on PBMC plays a role in mediating the differential catecholamine effects on cytokine production of PBMC. Furthermore, changes in cytokine expression induced by catecholamines favor Th2 responses.

Microarray analysis of human milk cells: persistent high expression of osteopontin during the lactation period.

To continue the search for immunological roles of breast milk, cDNA microarray analysis on cytokines and growth factors was performed for human milk cells. Among the 240 cytokine-related genes, osteopontin (OPN) gene ranked top of the expression. Real-time PCR revealed that the OPN mRNA levels in colostrum cells were approximately 100 times higher than those in PHA-stimulated peripheral blood mononuclear cells (PBMNCs), and 10 000 times higher than those in PB CD14(+) cells. The median levels of OPN mRNA in early milk or mature milk cells were more than three times higher than those in colostrum cells. Western blot analysis of human milk showed appreciable expression of full-length and short form proteins of OPN. The concentrations of full-length OPN in early milk or mature milk whey continued to be higher than those in colostrum whey and plasma as assessed by ELISA. The early milk (3-7 days postpartum) contained the highest concentrations of OPN protein, while the late mature milk cells (1 years postpartum) had the highest expression of OPN mRNA of all the lactating periods. The results of immunohistochemical and immunocytochemical staining indicated that OPN-producing epithelial cells and macrophages are found in actively lactating mammary glands. These results suggest that the persistently and extraordinarily high expression of OPN in human milk cells plays a potential role in the immunological development of breast-fed infants.

Insulin-like growth factor-I stimulates IL-10 production in human T cells.

There is vast body of evidence that the insulin-like growth factor (IGF)-I exerts immunomodulatory effects in vitro and in vivo. In vitro studies indicate that stimulatory effects of IGF-I may be exerted through augmentation of inflammatory cytokine production. To further explore the immunomodulatory effects of IGF-I through regulation of cytokine production, we tested the in vitro effects of IGF-I on the secretion of inflammatory T helper cell type 1 (Th1) and Th2 cytokines by human peripheral blood mononuclear cells (PBMC). To this end, PBMC were stimulated with the T cell mitogen phytohemagglutinin (PHA), and cytokines in the culture media were assessed after 18, 42, 66, and 80 h of culture. We found that IGF-I stimulated the secretion of the Th2 cytokine interleukin (IL)-10 by 40-70% in PHA-stimulated PBMC. In addition, we observed a small stimulatory effect (15%) on the secretion of another Th2 cytokine IL-4. The secretion of IL-2, IL-5, IL-6, interferon-gamma, and the inflammatory cytokines IL-1beta, IL-8, and tumor necrosis factor alpha was not or was hardly affected. IL-10 secretion was also stimulated in purified T cells, and we established that IGF-I also stimulated IL-10 mRNA expression by 100-150%. The monocyte-activating bacterial cell-wall product lipopolysaccharide induced IL-10 production in PBMC, but this was not affected by IGF-I. As IL-10 predominantly exerts anti-inflammatory actions and suppresses Th1-dependent immune responses, our results indicate that IGF-I may exert inhibitory actions on inflammatory and Th1-mediated cellular immune responses through stimulation of IL-10 production in T cells.