The role ofγδ T cells in the normal and disordered immune system

Summary A small population of T cells does not express the conventional T cell receptor characterized by the and polypeptide chains (TCR) but instead, two polypeptides termed and (TCR). This alternative receptor is able to recognize antigen. It appears early in T cell ontogeny, but its role in the thymus prior to the availability of TCR remains unclear. In selected sites such as skin or gut TCR predominates in mice which might suggest a role of T cells in the first line of defense against infection, T cells secrete lymphokines and display cytotoxic activity. However, their activation requirements may differ from what is known for T cells since MHC-nonrestricted and also CD4 and CD8 negative T cells have been described. Preferential activation by mycobacterial antigens possibly indicates a special repertoire of the T cells. In various diseases slightly increased numbers of T cells were found, but these preliminary studies have not yet provided evidence for a major pathogenetic role of T cells.List of abbreviations C constant region (immunoglobulin or TCR gene segment) - CD4 cluster of differentiation 4 (mainly on helper cells) - CD8 cluster of differentiation 8 (mainly on cytotoxic cells) - D diversity region (immunoglobulin or TCR gene segment) - DNA desoxyribonucleic acid - IL2 interleukin 2 - J joining region (immunoglobulin or TCR gene segment) - kD kiloDalton - MHC major histocompatibility complex - NK natural killer (cells) - RA rheumatoid arthritis - TCR T cell receptor - V variable region (immunoglobulin or TCR gene segment)     

Genetic characterization of an α-specific gene responsible for sexual agglutinability in Saccharomyces cerevisiae: mapping and gene dose effect

Summary A recessive ag1 mutation leads to specific defect in sexual agglutinability specifically in cells of the yeast Saccharomyces cerevisiae. The cryptopleurine resistance gene cry^R 1, closely linked to the mating type locus, was used to select / strains which emerged from / strains by mitotic nonreciprocal recombination, to genetically analyse ag1, since ag1 is expressed only in mating type. The ag1 gene was found to be linked to the centromere tightly, to met3 at 4.4 cM, and to ilv3 at 12 cM on chromosome X. Sexual agglutinability of cells was shown to be dependent on the dose of the AG1 gene, using / isogenic strains carrying AG1/AG1, AG1/ag1 or ag1/ag1. The sst2-1 mutation did not suppress the ag1 mutation. Based on these results, function of the AG1 gene is discussed.Abbreviations cM centimorgan - FDS first division segregation - NPD nonparental ditype - PD parental ditype - SDS second division segregation - TT tetratype     

Modulation of hematopoietic colony formation of stem cells in peripheral blood by anti-TGF-β in patients with severe immunosuppression

Summary The influence of transforming growth factor- (TGF-) on hematopoiesis has been evaluated by adding blocking antibodies against TGF- to colony forming assays (CFU-c). When optimum concentrations of recombinant growth factors, granulocyte-macrophage colony stimulating factor (GM-CSF), and interleukin-3 (IL-3) were added to stem cells from the peripheral blood of healthy individuals and certain patients with tumors or HIV infection, the anti-TGF- capable of blocking 5 ng/ml of active TGF- had no significant influence on erythroid or myeloid colony formation. However, in certain immunosuppressed individuals, anti-TGF- resulted in a significant decrease of erythroid colony formation and slight suppression of myeloid colony formation. The significant inhibition of hematopoiesis by plasma of HIV patients could be due to the presence of active forms of TGF-. The results of the blocking experiments are consistent with the concept that TGF- in low concentrations is essential for erythropoiesis and myelopoiesis but that higher levels of TGF- primarily inhibit erythropoiesis in vitro. TGF- serves as a coordinating factor when efficient recruitment of granulocytes and monocytes is more essential than erythropoiesis and stem cell growth.Abbreviations BFU-E burst forming unit-erythroid - CFC colony forming cells - CFU-GEMM colony forming unit-granulocyte/erythroid/macrophage/megacaryocyte - CFU-GM colony forming unit-granulocyte/macrophage - EPO erythropoietin - GM-CSF granulocyte/macrophage-colony stimulating factor - HIV human immunodeficiency virus - IL-1 interleukin-1 - IL-3 interleukin-3 - IMDM Iscove's Modified Dulbecco's medium - PBS phosphate buffered saline - TGF- transforming growth factor- - TNF- tumor necrosis factor-     

Combined effect of hydrogen peroxide induced oxidative stress and IL-1 alpha on IL-8 production in CaCo-2 cells (a human colon carcinoma cell line) and normal intestinal epithelial cells

Oxidative stress, IL-1, and IL-8 are known to contribute to mucosal inflammation of the gastrointestinal tract. We examined the IL-8 response after brief exposure to hydrogen peroxide induced oxidative stress in CaCo-2 cells (a human colon carcinoma cell line) and in human intestinal epithelial cells. In addition, we examined whether exposure to oxidative stress, followed by IL-1, could modulate IL-8 production. A transient up-regulation of IL-8 mRNA expression was observed after hydrogen peroxide treatment. Hydrogen peroxide induced oxidative stress was also observed to promote IL-8 secretion. Exposure to hydrogen peroxide, followed by IL-1, enhanced IL-8 production over that achieved with IL-1 alone. Thus, oxidative stress and IL-1 were observed to cooperatively enhance IL-8 production.     

Acute ethanol consumption synergizes with trauma to increase monocyte tumor necrosis factor α production late postinjury

The hypothesis that acute ethanol uptake plus trauma can synergize to increase immunosuppression was tested. We found that, unlike non-alcohol-exposed patients, patients with acute alcohol use prior to trauma have a transient decrease in monocyte tumor necrosis factor (TNF) production during the very early postinjury (0–3 days) period. However, TNF production by these alcoholexposed patients' monocytes (MØ) became hyperelevated late postinjury (>9 days). Consequently, these massively elevated MØ TNF levels can contribute to posttrauma immunosuppression after acute alcohol use. We also demonstrate that normal monocyte activation with the superantigen,Staphylococcus enterotoxin B (SEB), results in a preferential induction of cellassociated MØ TNF production, described as characteristic of immunosuppressed trauma patients. Acutein vitro ethanol treatment down-regulated the elevated TNF production by trauma patients' MØ after either SEB, muramyl-dipeptide (MDP), interferon- plus MDP, or lipopolysaccharide (LPS) stimulation. Both SEB- and LPS-induced TNF mRNA induction was inhibited by acute alcohol treatment in normal MØ, indicating that ethanol can regulate cytokine gene expression. An additional immunosuppressive effect of acute ethanol's stimulation was suggested by its induction of elevated transforming growth factor production in trauma patients' activated MØ.     

Circulating cytokine concentrations and cytokine production by monocytes from newborn babies and adults

As a possible factor responsible for reduced fever responses in the newborn, we measured plasma cytokine concentrations and cytokine production by neonatal monocytes after lipopolysaccharide or IL (interleukin)-1 stimulation in vitro and compared these data with those obtained from adult plasma and monocytes. Whole blood was collected from afebrile adults (n=12) and the umbilical cord of normal term infants (n=12). Plasma and peripheral blood monocytes were prepared by conventional techniques. Significantly lower concentrations of IL-1, IL-1 (P<0.05,t-test) and IL-6 (P< 0.01,t-test) were found in the plasma of newborn babies compared with that of adults. There was no significant difference in plasma tumour necrosis factor (TNF) concentrations between the adults and newborn babies. Monocytes from newborn babies had the capacity to produce IL-1 and IL-1 as readily as adult cells after stimulation with lipopolysaccharide or IL-1, and produced significantly lower concentrations of TNF and IL-6 than those produced by stimulated adult monocytes (P< 0.01, ANOVA). Our results suggest that the reduced production of IL-6 by monocytes of the newborn during infection could be partly responsible for attenuated fever responses observed in the neonate.     

Expression ofβ1 integrins in non-neoplastic mammary epithelium,fibroadenoma and carcinoma of the breast

1 Integrins were examined immunohisto-chemically in normal and mastopathic mammary glands, 12 benign tumours and 90 carcinomas of the breast using monoclonal antibodies against1 and1 to6 subunits. When compared with epithelial cells of non-neoplastic mammary glands and of benign tumours, carcinoma cells showed considerable quantitative changes in the pattern of2,3 and6 subunit expression. In contrast, the distribution pattern of1,1,4 and5 antigens corresponded to the situation observed in non-neoplastic mammary gland epithelium in most instances. An abnormal expression of2 was found in 71.0% of the carcinomas ranging from a remarkably low number of2-positive tumour cells in 27.5% of the cases to a complete absence of the2 molecule in 43.5% of the carcinomas. Of the carcinomas 39.9% exhibited quantitative changes in3 expression with an abnormally low content of3-positive neoplastic cells in 15.4% and a complete absence of this molecule in 24.5% of the cases. Expression of6 was abnormal in 73.2% of the carcinomas, consisting in a greater number of6-negative tumour cells in 31.9% and in a complete absence of6 in 41.3% of the tumours. The abnormally low expression/absence of2 and3 subunits correlated with oestrogen receptor negativity (P<0.033 andP<0.04, respectively). In addition, abnormally low expression/absence of2 correlated with poor differentiation of the tumours (P< 0.014). The quantitative changes in the expression pattern of1-associated subunits in breast carcinomas may cause a disturbed cell-cell and/or cell-matrix interaction that increases the invasive and migratory property of the tumour cells.     

Interactions of P 1507, a new antioxidant agent,with phagocyte functions

Toxic oxygen free radicals are believed to play a role in the pathogenesis of a number of respiratory diseases. In particular, pulmonary emphysema may occur because of the oxidative impairment of 1-proteinase inhibitor (1-PI). We reportin vitro data on a new thiol agent, P 1507 [N-5-(thioxo-l-prolyl)-l-cysteine], obtained in a series of experiments designed in view of its therapeutic potential in these clinical conditions. We found that P 1507 at the concentration of 5×10^–6 M was able to almost fully abolish the PMA-triggered PMN-induced oxidative impairment of 1-PI. Protection may be due to the radical scavenger ability P 1507, that markedly reduced superoxide anion production from PMNs. We also found that P 1507 did not significantly impair other defence mechanisms of PMNs (i.e. phagocytosis, chemotaxis and bactericidal activity). The release of cytokines (TNF-, IL-6 and IL-8) from monocytes was not altered in the presence of P 1507. We conclude that the compound P 1507 may be considered for treatment of clinical conditions characterized by overload of oxidants, on the basis of its ability in preventing the oxidative damage of 1-PI and of a lack of unwanted inhibitory effects towards defence mechanisms of phagocytes.     

Flow Cytometric Analysis of In Vitro Proinflammatory Cytokine Secretion in Peripheral Blood from Multiple Sclerosis Patients

The cytokines, interferon- (IFN-), tumor necrosis factor- (TNF-rpar;, and interleukin-2 (IL-2) are important endogenous proinflammatory proteins and have been linked to disease activity in multiple sclerosis. In this study, we use flow cytometric methodology to compare the secretion of IFN-, IL-2, and TNF- from peripheral blood-derived T cells of multiple sclerosis patients to the secretion in healthy controls. The percentages of IFN-, IL-2, and TNF- secreting cells are not significantly different between multiple sclerosis patients and controls. However, the TNF- secreting CDS cell percentage is correlated with the IFN- and IL-2 secreting CD3 cell percentages in multiple sclerosis patients. In the controls, only the TNF- secreting CD3 cell percentage is correlated with IFN-. These findings show that correlated secretion of cytokines occurs in multiple sclerosis and suggest that concerted intercytokine interactions may play an important role in the disease.     

Pharmacological characterization of P2X7 receptors in rat peritoneal cells

Objective and design: P2X₇ receptor activation by ATP results in the release of IL-1 and IL-18. Prolonged stimulation can lead to pore formation and cell death. In this study we pharmacologically characterized P2X₇ receptors on rat peritoneal cells (RPC) and on 1321N1 cells transfected with rat P2X₇ receptor (1321rP2X₇-11).Materials and methods: RPC were isolated from rats by lavage. P2X₇ agonist induced pore formation in RPC was measured by EtBr uptake. P2X₇-stimulated pore formation and Ca⁺⁺ influx in 1321rP2X₇-11 cells were measured by a fluorometric imaging plate reader. The effects of pyridoxal phosphate-6-azo phenyl –2-4-disulfonic acid (PPADS) on pore formation and Ca⁺⁺ influx were examined in both RPC and 1321rP2X₇-11. P2X₇-mediated IL-1 release in RPC and the effect of PPADS were determined.Results: RPC express functional P2X₇ receptors that were activated by ATP analogs with a rank order of potency of 2- 3-O-(4-Benzoylbenzoyl) adenosine 5-triphosphate (BzATP) > ATP > ,-methylene ATP. Activation of P2X₇ receptors by BzATP was inhibited by PPADS. Similar results were also obtained in 1321rP2X₇-11 cells. Activation of P2X₇ receptors on RPC resulted in IL-1 secretion, which was inhibited by PPADS.Conclusions: RPC express functional P2X₇ receptors that form pores and mediate the release of IL-1.Received 20 July 2004; returned for revision 9 September 2004; accepted by N. Boughton-Smith 5 November 2004     

alpha1-acid glycoprotein possesses in vitro pro- and antiinflammatory activities

We studied the effects of ₁-acid glycoprotein on tumor necrosis factor- (TNF-) and interleukin-10 (IL-10) production and lymphocyte response to phytohemagglutinin in cultured peripheral blood mononuclear leukocytes from 6 healthy donors. We observed 2 opposite responses to ₁-acid glycoprotein: first, stimulation of TNF- and IL-10 production and inhibition of lymphocyte proliferation, and second, suppression of cytokine production and stimulation of lymphocyte proliferation. In cell cultures isolated from 4 of 6 donors, the TNF-/IL-10 ratio remained unchanged after addition of native ₁-acid glycoprotein, but some fractions isolated by chromatography on concanavalin A-Sepharose changed this parameter. These changes were most pronounced after treatment with fraction C enriched with molecules with incomplete (biantennary) carbohydrate chains. The mechanisms of ₁-acid glycoprotein-induced effects on peripheral blood mononuclear leukocytes are discussed.     

Presence of two isoforms of Na,K-ATPase with different pharmacological and immunological properties in the rat kidney

Previous studies have demonstrated the presence of two populations of Na,K-ATPase with distinct kinetic, pharmacological and immunological characteristics along the rabbit nephron, indicating that the proximal segments of the nephron express exclusively the ₁ isoform of the catalytic subunit, whereas the collecting duct expresses an ₃-like isoform. Because pharmacological studies have shown the existence of two populations of Na,K-ATPase with different sensitivities to ouabain in the rat cortical collecting duct, which may result from the presence in the same nephron segment of the two isoforms demonstrated in the different segments of the rabbit nephron, the present study was undertaken to characterize the properties of Na,K-ATPase along the rat nephron. Results indicate that each segment of the rat nephron contains two subpopulations of Na,K-ATPase: a component highly sensitive to ouabain (IC₅₀ 5.10^–6 M) which is recognized by an anti- ₃ antibody and another moiety of lower affinity for ouabain (IC₅₀ 5.10^–4 M) which is recognized by an anti- ₁ antibody. Whether these two subpopulations correspond to different isoforms of the subunit of Na,K-ATPase ( ₁ and ₃-like) remains to be determined.     

Immunohistochemical studies on oncogene products (EGF-R,c-erbB-2) and growth factors (EGF,TGF-α) in human breast cancer: their relationship to oestrogen receptor status,histological grade,mitotic index and nodal status

Summary In this investigation, 83 human mammary carcinomas were examined for the expression of oestrogen receptor (ER), epidermal growth factor receptor (EGF-R), epidermal growth factor (EGF), transforming growth factor alpha (TGF-), c-erbB-2, histological grade, mitotic index and nodal status, all of which are reportedly prognostically significant factors (Bloom and Richardson 1957; Baak et al. 1985; Wright et al. 1989). ER expression was biochemically recognized in 43.4% of mammary carcinomas, and EGF-R, EGF, TGF- and c-erbB-2 were histochemically recognized in 25.3, 14.5, 27.7 and 18.0% of mammary carcinomas examined respectively, using conventional sections of buffered formalin-fixed, paraffin-embedded tissue and monoclonal or polyclonal antibodies. There were significant relationships between negative ER and positive EGF-R or TGF-; positive EGF-R and TGF-; positive EGF-R and c-erbB-2; and positive c-erbB-2 and TGF-. The single changes which were the negative ER and the positive c-erbB-2 correlated with histological grade and mitotic index. Co-expression of EGF-R and TGF- correlated with positive nodal status. Therefore, the present investigation indicates that the negative ER, single expression of c-erbB-2 and co-expression of EGF-R and TGF- are important markers which contribute indirectly to prognosis, which reconfirms previous findings on the former two while adding the new finding that immuno-histochemical demonstration of expression of EGF-R and TGF- may provide useful information for selecting the appropriate treatment.     

Down-regulation of tumor necrosis factor α activity by acute ethanol treatment in human peripheral blood monocytes

As the most commonly used drug that can modulate both metabolic and immune pathways, ethanol is evaluated in this report as a regulator of tumor necrosis factor (TNF) production in human peripheral blood monocytes (M) in combination with a variety of stimuli. While acute ethanol treatment did not induce TNF in M, it was a potent down-regulator of M TNF production whether induced by the combination of interferon- plus muramyl dipeptide (MDP) (P<0.001), lipopolysaccharide (LPS) alone (P<0.01), or interferon- plus LPS. Down-regulation of M TNF by ethanol was dose dependent and statistically significant in the biologically relevant, 25–150 mM, ethanol concentration range. We also demonstrate that these ethanol concentrations did not affect M viability. TNF down-regulation by ethanol was most effective when ethanol was administered 4 hr prior to MDP stimulation; however, it was also effective—though to a lesser extent—if it was added at the time of MDP stimulation. Furthermore, ethanol also down-regulated TNF production of thein vivo preactivated M of trauma patients, which produce hyperelevated levels of TNF. We have previously shown that the majority of posttrauma elevated M TNF is produced by the M subpopulation expressing high-affinity type I Fc receptors (FcRI). When the FcRI cross-linking-stimulated M subpopulation was treated with acute ethanol, TNF production was suppressed again both inin vivo preactivated M of trauma patients and in M of normal controls. In experiments utilizing cyclooxygenase inhibitor, we also demonstrate that ethanol has a direct, prostaglandin E₂-independent, effect on M TNF production. These results demonstrate that acute ethanol exposure has the potential to down-regulate M production of TNF significantly regardless of the TNF-inducing stimulus. Decreased capacity of M to produce TNF might, therefore, contribute to the immunological and metabolic abnormalities described after ethanol uptake.     

Regulated overproduction of α-amylase by transformation of the amylolytic yeast Schwanniomyces occidentalis

Summary High frequency transformation of a Schwanniomyces occidentalis mutant defective in the last step of tryptophan synthesis was achieved with plasmids containing the tryptophan synthetase gene (TRP5) of Saccharomyces cerevisiae and an autonomous replication sequence from S. occidentalis, which we called SwARS1. The SwARS1 fragment is also functional in S. cerevisiae. The average copy number of the plasmids in both yeast species was 5–10 per cell under selective conditions. S. occidentalis cells that were transformed with an autonomously replicating plasmid carrying the cloned -amylase gene from S. occidentalis secreted about five times more -amylase than cells without additional copies of the -amylase gene. Both the chromosomal copy and the plasmid-carried copies of the -amylase gene were repressed in the presence of glucose. This transformation system provides a possibility to improve starch degradation by S. occidentalis.     

Potential roles for tumour necrosis factorα during embryonic development

This paper reviews the evidence indicating possible roles for tumour necrosis factor-alpha (TNF) in development. It is proposed that TNF may have essentially three major roles during embryonic development, which may be analogous to its roles in the immune system and during inflammation: a role in programmed cell death; a role as a cellular growth and differentiation factor; and also a role in the remodelling of extracellular matrix, and the regulation of cell adhesion molecules and integrins. The concept of the existence of a cytokine array during embryogenesis, analogous to that occurring in inflammation, is discussed, as well as potential roles for TNF in the induction of ubiquitin; protective mechanisms embryonic cells may employ against TNF-mediated cytotoxicity; and a consideration of the role TNF may play in a free radical theory of development.     

Altered synthesis of interferon-γ and expression of interferon-γ receptor by peripheral blood mononuclear cells from patients with IgA nephropathy and non-IgA proliferative glomerulonephritis

Previously we reported disease-specific interaction between interferon- (IFN-) and interleukin-4 (IL-4) in patients with IgA nephropathy (IgAN), suggesting the existence of unusual T cell behavior in this disease. In the present study, we investigated characteristic synthesis of interferon- (IFN-) and expression of IFN- receptor (IFN-R) in the peripheral blood mononuclear cells (PBMC) from patients with IgAN and other chronic proliferative glomerulonephritis (PGN). Heparinized peripheral blood samples were obtained from 38 patients with chronic mesangial proliferative glomerulonephritis (CGN; including 24 with IgA nephropathy) and 20 healthy controls. PBMC were isolated by gradient centrifugation and fragments were cultured in Iscove's modified Dulbecco's medium (IMDM) supplemented with 10% fetal calf serum (FCS) for 72 hr. IFN- concentrations in supernatants were evaluated by the enzyme-linked immunosorbent assay (ELISA). Other parts of PBMC pellets were reacted with anti-human IFN-R monoclonal antibody and FITC-labeled anti-mouse second antibody for analysis of IFN-R expression on these cells by FACScan. The remaining PBMC were fractionated into CD4⁺ T cells, CD8⁺ T cells, B cells, NK, cells and macrophages using the MACS cell sorting system. The isolated cells were evaluated for IFN- or IFN-R mRNA expression by the semiquantitative RT-PCR method.In vitro IFN- synthesis was enhanced in patients with CGN, and NK cells were revealed to be responsible for such enhancement. On the other hand, the expression of IFN-R on macrophages was suppressed in CGN patients. These results suggest that impairment of regulation of the IFN- system might be involved in the development of CGN.     

Differential effects of prednisolone and indomethacin on zymosaninduced inflammation in a modified murine tissue-chamber model

A tissue-chamber model of inflammation in mice has been modified and used to investigate the kinetics of zymosan-induced inflammatory mediators such as tumour necrosis factor (TNF), interleukin-1 (IL-1) and prostaglandin E₂ (PGE₂). In addition, the influx of polymorphonuclear leukocytes (PMN) into the chamber fluid and the granuloma surrounding the chamber was measured by myeloperoxidase (MPO) activity using a new microtitre plate assay. TNF and IL-1 reached peak concentrations at 3 and 6 h respectively after zymosan injection. Intermediate high concentrations of IL-1 were observed until the end of the experiment at 72 h, but TNF concentrations decreased from 24 h to biologically insignificant values. In contrast, exudate PGE₂ and MPO activity increased up to 24 h after zymosan injection and remained high until 72 h. At 6h after zymosan challenge, oral pre-treatment with prednisolone (3 to 30mg/kg) dose-dependently reduced TNF, IL-1 and PGE₂ concentrations while indomethacin (0.3 to 3 mg/kg) significantly attenuated PGE₂, slightly enhanced TNF and had no effect on IL-1 concentrations in the exudate. Both drugs had similar potencies against exudate and tissue MPO activities. Prednisolone inhibited IL-1 at 72 h post-zymosan. Indomethacin was more potent than prednisolone against PGE₂ (ID₅₀ of <0.3 versus 0.6mg/kg). The data obtained confirm the usefulness and reliability of this model in evaluating the effects of anti-inflammatory agents on inflammatory mediators induced by zymosan.     

β subunits determine the time course of desensitization in rat α3 neuronal nicotinic acetylcholine receptors

Standard two-electrode voltage-clamp techniques were used to investigate some of the pharmacological and functional properties of two types of rat neuronal nicotinic acetylcholine receptors expressed in Xenopus oocytes after pairwise injection of 34 or 32 mRNAs. Currents of several A amplitude were elicited by fast application of micromolar concentrations of either acetylcholine (ACh) or 1,1-dimethyl-4-piperazine (DMPP). The activation of either receptor type by DMPP showed cooperativity (Hill coefficient, n1.7) with a half-maximal activation concentration (EC₅₀) of 15–30 M. In 34 receptors, ACh displayed cooperativity (n=1.8) but was less efficacious than DMPP, yet its EC₅₀ was about equal to that of DMPP. Finally, in 32 receptors, ACh was much less efficacious and had a much lower EC₅₀. Desensitization induced by either DMPP or ACh was slow in 34 nicotinic ACh receptors but was rapid and extensive in 32 receptors, causing a significant proportion of the response to wane within the first few seconds of agonist application.     

Synoviocytes in chronic synovitis in situ and cytokine stimulated synovial cells in vitro neo-express α1, α3 and α5 chains of β1 integrins

The expression of the 1 integrins was examined immunohistochemically in synoviocytes from normal synovial membrane and from chronic synovitis of different aetiology and intensity. Normal synoviocytes were 61-positive but lacked 1 through 5. In mild inflammation type A synoviocytes neo-expressed 1, 3, and 5 chains. In severe inflammation both type A and B synoviocytes expressed 3, 4, 5, and 6 chains. The effects of inflammatory cytokines, as single agents or in combination, on the 1 integrin expression in cultured normal synoviocytes was determined by immunocytochemistry and flow cytometry. The 1 chain, while absent in unstimulated synoviocytes, was induced by interleukin-1 (IL-1), tumour necrosis factor- (TNF-), and interferon- (INF-). This effect was enhanced by combining IL-1 and TNF-. Expression of the 3 chain was up-regulated by IL-1 and, more intensely, by IFN-. Transforming growth factor (TGF-) inhibited the up-regulating effect of IL-1 and antagonized the effect of IFN- on 3 chain expression. Expression of the 5 chain was up-regulated significantly by co-stimulation through IL-1 together with TGF- or TNF-. Thus, the 1 integrin profile of cytokine activated synoviocytes in vitro resembled that of synoviocytes in synovitis in situ. These data suggest that IL-1, TNF-, IFN-, and TGF- are likely to be among the effectors regulating 1 integrin expression in synoviocytes in vivo.