C-C chemokine profile of cord blood mononuclear cells: selective defect in RANTES production

Three C-C chemokines inhibit human immunodeficiency virus (HIV) entry into macrophages: macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and regulated-upon activation, normal T-cell expressed and secreted (RANTES). We studied the ability of placental cord blood mononuclear cells (CBMC) to secrete these C-C chemokines in comparison to adult blood mononuclear cells (ABMC). CBMC had diminished ability to secrete RANTES, as determined by enzyme-linked immunosorbent assay. Secretion of MIP-1alpha and MIP-1beta were similar in CBMC and ABMC. Whereas MIP-1alpha and MIP-1beta secretion were comparable in monocytes and lymphocytes, RANTES was secreted primarily by lymphocytes. Flow cytometric analysis of RANTES expression showed diminished intracellular RANTES expression in cord blood lymphocytes (CBL) compared to adult (peripheral) blood lymphocytes (ABL). A subset analysis of RANTES-producing CBL and ABL demonstrated that RANTES was produced predominantly by CD8+/CD45RO+ cells. CBL had a reduced proportion of CD8+/CD45RO+ cells compared with ABL, which may account for the diminished RANTES secretion by CBMC. These results may be relevant to the pathogenesis of perinatal HIV infection. (Blood. 2000;95:715-718)     

MIP-1alpha and TGF-beta production in CD34+ progenitor-stromal cell coculture systems: effects of progenitor isolation method and cell-cell contact

ABSTRACT Macrophage inflammatory protein-1alpha (MIP-1alpha) is a C-C chemokine which has antiproliferative effects on early hematopoietic progenitors and stimulatory effects on later progenitors. It also possesses chemotactic and activating properties for monocytes, macrophages, and T-cells. CD34+ progenitors isolated utilizing an avidin-biotin immunoadsorption column produced significant amounts of MIP-1alpha from 24 h onward when cultured in medium with 10% fetal calf serum (>200 pg/ml). Such production persisted through 96 h of culture and was greater when such progenitors were cocultured with a preformed marrow stromal layer (4000 pg/ml at 24 h). The production of MIP-1alpha declined over time of coculture with stromal layers, and stromal layers themselves produced minimal MIP-1alpha as detected by ELISA: <100 pg/ml. In contrast, CD34+ cells isolated by flow cytometry or by magnetic bead adsorption produced minimal MIP-1alpha (0-30 pg/ml). MIP-1alpha production also increased when cells isolated by these two methods were cocultured with stromal layers. The difference in MIP-1alpha production could not be accounted for by differences in purity of the CD34+ population between isolation methods nor on the basis of monocytic or lymphocytic contamination as assessed by the presence of CD14 or CD3 positive cells. CD34+ cells isolated by immune adsorption had increased expression of endothelial and mesenchymal associated antigens, however, suggesting that this subpopulation might account for the MIP-1alpha production observed. Freshly isolated CD34+ cells expressed MIP-1alpha message as assessed by RT-PCR and by in situ hybridization. Coculture of CD34+ cells isolated by any means with stromal cells increased transforming growth factor-beta (TGF-beta) production, in this case by the stromal layer itself. Both MIP-1alpha and TGF-beta have been found to influence cell cycle status and proliferation status of early hematopoietic progenitors, and both have potential effects on accessory cell function. These studies indicate that progenitor-stromal cell interactions may influence local cytokine output, thus potentially influencing progenitor cycling status and accessory cell activation. The method of isolation of CD34+ progenitors may influence secretion of certain cytokines and chemokines.     

Role of immune dysfunction in pathogenesis of type 1 diabetes mellitus in children

Objective:To investigate the function of cytokines,chemokines,and regulatory T cells(Tregs)in the pathogenesis of Type 1 diabeles mellitus(T1DM)in children.Methods:A total of 35 children with T1DM and 30 healthy controls were enrolled in this study.Levels of serum cytokines(IL-1α,IL-6,IL-10,IL-12,and TNF-α)and chemokines(MIP-1α,MIP-1βand MCP-1)were detected by enzyme-linked immunosorbent assay.Peripheral blood mononuclear cells(PBMCs)were isolated and culture supernatant of phytohaemagglutinin(PHA)-stimulatcd PBMCs was subjecled to ELISA for levels of cytokines(IL-1α,IL-6,IL-10,IL-12 and TNV-α)in T1DM and control group.Furthermore,flow cytometty was used to determine the percentage of Tregs in PBMCs of two groups.Results:Levels of serum cytokines including IL-1α,IL-6,IL-10 andd TNF-αas well as chemokines,such as MIP-1αand MIP-1βin children with T1DM children were significantly higher than those in healthy controls(P0.05,respectively).PBMCs with PHA stimulation in T1DM group secreted more IL-1αand TNF-α(P0.05,respectively),but less IL-10(P0.05),as compared with control group.Furthermore,the proportion of CD4~+,CD25~+,Foxp3.Tregs in PBMCs isolated from children with T1DM was obviously lower than those in heathy controls(P0.05).Conclusions:Immune dysfunction.with uprcgulation of inflanunatory factors such as IL-1α.IL-6.TNF-αand MIP-1α.downregulation of IL-10 and Tregs,plays an important role in the pathogenesis of T1DM in children.     

趋化因子及其受体与冠心病关系的研究进展

动脉粥样硬化(AS)是慢性炎性及代谢性疾病,脂质沉积和炎性细胞浸润至血管内皮下是形成AS的主要原因,但是炎性细胞浸润的机制尚未阐明。许多国内外研究表明,趋化因子对单核细胞、巨噬细胞、T细胞等炎性细胞的迁移、活化在AS炎症反应中起重要作用。新近研究证实,趋化因子可促使血管平滑肌细胞增殖以及炎症因子和基质金属蛋白酶的合成,促进斑块不稳定的关键环节。本文就趋化因子及其受体在AS发生发展中的作用予以综述。     

Nurse-like cells from patients with rheumatoid arthritis support the survival of osteoclast precursors via macrophage colony-stimulating factor production

OBJECTIVE: To elucidate the role of nurse-like cells (NLCs) obtained from rheumatoid arthritis (RA) patients in bone loss during progressive synovial expansion. METHODS: CD14+ monocytes were cocultured with NLCs for 4 weeks and collected as NLC-supported CD14+ (NCD14+) monocytes. To determine their ability to differentiate into osteoclasts, NCD14+ monocytes were further cultured with macrophage colony-stimulating factor (M-CSF) together with RANKL or tumor necrosis factor alpha (TNFalpha). NCD14+ monocytes were also cocultured with SaOS-4/3 cells, which were shown to support osteoclastogenesis in response to parathyroid hormone (PTH). CD14+ monocytes were cocultured with SaOS-4/3 cells to elucidate how SaOS-4/3 cells and NLCs supported CD14+ monocytes for a long period. Synovial expansion adjacent to bone in RA patients was examined immunohistochemically to detect osteoclast precursors such as NCD14+ monocytes. RESULTS: NLCs supported the survival of CD14+ monocytes for 4 weeks. NCD14+ as well as CD14+ monocytes differentiated into osteoclasts in the presence of M-CSF together with RANKL or TNFalpha. NCD14+ monocytes also differentiated into osteoclasts in PTH-treated cocultures with SaOS-4/3 cells. SaOS-4/3 cells supported the survival of CD14+ monocytes for 4 weeks in the presence, but not absence, of PTH. Treatment of SaOS-4/3 cells with PTH up-regulated the expression of M-CSF messenger RNA. Neutralizing antibodies against M-CSF inhibited the NLC-supported survival of CD14+ monocytes. CD68+ monocytes and M-CSF+ fibroblast-like synoviocytes were colocalized in regions adjacent to the destroyed bone of RA patients. CONCLUSION: Our findings suggest that NLCs are involved in RA-induced bone destruction by maintaining osteoclast precursors via production of M-CSF.     

A macrophage marker, Siglec-1, is increased on circulating monocytes in patients with systemic sclerosis and induced by type I interferons and toll-like receptor agonists

OBJECTIVE: Microarray analyses of peripheral blood leukocytes have shown that patients with systemic lupus erythematosus express increased levels of type I interferon (IFN)-regulated genes. In this study we examined gene expression by peripheral blood mononuclear cells (PBMCs) from patients with systemic sclerosis (SSc) to better understand the dysregulation of the immune system in this disease. METHODS: PBMC gene expression was analyzed by microarray and confirmed by real-time polymerase chain reaction (PCR). Surface protein expression of Siglec-1 was analyzed by flow cytometry in PBMCs from healthy control subjects and patients with SSc, and in control PBMCs that were cultured in vitro with Toll-like receptor (TLR) agonists. RESULTS: SSc patients showed increased expression of a cluster of IFN-regulated genes, including Siglec-1 (CD169, sialoadhesin). This result was verified and extended by real-time PCR, showing that a subset of the SSc patients expressed strikingly increased levels of Siglec-1 messenger RNA (mRNA). Flow cytometry of PBMCs from SSc patients and healthy controls showed increased Siglec-1 surface protein expression, which was restricted to CD14+ monocytes. In vitro studies showed that type I IFN and certain TLR agonists, including TLR-7 and TLR-9, induced Siglec-1 mRNA and protein expression. Moreover, TLR induction of surface Siglec-1 was shown to be type I IFN-dependent. Increased numbers of Siglec-1+ cells were observed by immunohistochemistry in the skin of SSc patients compared with healthy controls. CONCLUSION: Increased expression of Siglec-1 in circulating SSc monocytes and tissue macrophages suggests that type I IFN-mediated activation of monocytes occurs in SSc, possibly through TLR activation of IFN secretion. These observations indicate a potential role for type I IFN-activated monocyte/macrophages in the pathogenesis of SSc.     

β-Glucan attenuates inflammatory responses in oxidized LDL-induced THP-1 cells via the p38 MAPK pathway

AimTo investigate the immunomodulatory effects of β-(1,3/1,6)-d-glucan on atherosclerosis as well as on the molecular mechanisms of its transition.Methods and resultsHuman monocytic leukemia (THP-1) cells were differentiated into the macrophage phenotype by incubation with oxLDL in the absence or presence of β-glucan. β-glucan attenuated CD86 and CD80 expression and simultaneously reduced secretion of the inflammatory cytokines IL-2, IL-8, IL-12, TNF-α and IFN-γ. Western blot analysis showed that oxLDL treatment induced phosphorylation of p38 MAPK and ERK1/2 in PMA-differentiated THP-1 cells. However, β-glucan inhibited p38 MAPK activation. In experiments with monocytes derived from healthy donors, β-glucan inhibited IL-8, IL-12 and TNF-α production. The anti-inflammatory effects of β-glucan were also observed in atherosclerotic plaque cells.Conclusionsβ-glucan inhibited oxLDL-induced pro-inflammatory effects in macrophages via regulation of p38 MAPK phosphorylation. This novel finding may provide insight for new therapeutic strategies.     

CC chemokines and the receptors CCR3 and CCR5 are differentially expressed in the nonneoplastic leukocytic infiltrates of Hodgkin disease

Lymph nodes with Hodgkin disease (HD) harbor few neoplastic cells in a marked leukocytic infiltrate. Since chemokines are likely to be involved in the recruitment of these leukocytes, the expression of potentially relevant chemokines and chemokine receptors were studied in lymph nodes from 24 patients with HD and in 5 control lymph nodes. The expression of regulated on activation, normal T cell expressed and secreted (RANTES), monocyte chemotactic protein (MCP)-1, macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta was analyzed by in situ hybridization and that of CCR3 and CCR5 by immunohistochemistry and flow cytometry. It was found that, overall, the expression of all 4 chemokines was markedly enhanced, but the cellular source was different. RANTES was expressed almost exclusively by T cells whereas the expression of MCP-1, MIP-1alpha, and MIP-1beta was confined largely to macrophages. In control lymph nodes, chemokine expression was low, with the exception of MIP-1alpha in macrophages. CCR3 and CCR5 were highly expressed in T cells of HD involved but not of control lymph nodes. CCR3 was equally distributed in CD4+ and CD8+ cells, but CCR5 was associated largely with CD4+ cells. In HD lymph nodes, CCR3 and CCR5 were also expressed in B cells, which normally do not express these receptors. All these chemokines and receptors studied, by contrast, were absent in the neoplastic cells. It was concluded that chemokines are involved in the formation of the HD nonneoplastic leukocytic infiltrate. Expression of CCR3 and CCR5 appears to be characteristic of HD, but the roles of these receptors' up-regulation for the disease process remain unclear.     

Augmented production of chemokines by the interaction of type II collagen-reactive T cells with rheumatoid synovial fibroblasts

OBJECTIVE: To determine the impact of type II collagen (CII)-reactive T cells on the production of chemokines in the joints of patients with rheumatoid arthritis (RA). METHODS: T cell proliferative responses to bovine CII were assayed in synovial fluid (SF) mononuclear cells and peripheral blood mononuclear cells. CII-stimulated T cells were cocultured with fibroblast-like synoviocytes (FLS). The expression of interleukin-8 (IL-8), monocyte chemoattractant protein 1 (MCP-1), and macrophage inflammatory protein 1 alpha (MIP-1 alpha) in the sera, SF, and supernatant of the CII-stimulated T cells and FLS coculture was measured by enzyme-linked immunosorbent assays. RESULTS: The levels of IL-8, MCP-1, and MIP-1 alpha in SF were significantly higher than those in paired sera of RA patients. IL-8, MCP-1, and MIP-1 alpha levels in SF were strongly correlated with T cell responses to CII. When FLS were cocultured with CII-stimulated T cells, the production of IL-8, MCP-1, and MIP-1 alpha was significantly increased. This increase correlated well with the T cell proliferative response to CII. Chemokine production by coculture of CII-stimulated T cells and FLS was mediated mainly by direct cell-cell contact through CD40 ligand-CD40 engagement. CONCLUSION: Our data indicate that the presence of CII-reactive T cells in RA joints can increase the production of chemokines such as IL-8, MCP-1, and MIP-1 alpha through interaction with FLS. This chemokine production is mediated by cell-cell contact, including CD40 ligand-CD40 engagement. These results suggest that CII-reactive T cells play a crucial role in the amplification and perpetuation of the inflammatory process in the rheumatoid synovium.     

Interaction with activated monocytes enhances cytokine expression and suppressive activity of human CD4+CD45ro+CD25+CD127low regulatory T cells

Objective

Despite the high frequency of CD4+ T cells with a regulatory phenotype (CD25+CD127^low FoxP3+) in the joints of patients with rheumatoid arthritis (RA), inflammation persists. One possible explanation is that human Treg cells are converted into proinflammatory interleukin‐17 (IL‐17)–producing cells by inflammatory mediators and thereby lose their suppressive function. The aim of this study was to investigate whether activated monocytes, which are potent producers of inflammatory cytokines and are abundantly present in the rheumatic joint, induce proinflammatory cytokine expression in human Treg cells and impair their regulatory function.

Methods

The presence and phenotype of CD4+CD45RO+CD25+CD127^low T cells (memory Treg cells) and CD14+ monocytes in the peripheral blood (PB) and synovial fluid (SF) of patients with RA were investigated by flow cytometry. Memory Treg cells obtained from healthy control subjects underwent fluorescence‐activated cell sorting and then were cocultured with autologous activated monocytes and stimulated with anti‐CD3 monoclonal antibodies. Intracellular cytokine expression, phenotype, and function of cells were determined by flow cytometry, enzyme‐linked immunosorbent assay, and proliferation assays.

Results

In patients with RA, the frequencies of CD4+CD45RO+CD25+CD127^low Treg cells and activated CD14+ monocytes were higher in SF compared with PB. In vitro–activated monocytes induced an increase in the percentage of IL‐17–positive, interferon‐γ (IFNγ)–positive, and tumor necrosis factor α (TNFα)–positive Treg cells as well as IL‐10–positive Treg cells. The observed increase in IL‐17–positive and IFNγ‐positive Treg cells was driven by monocyte‐derived IL‐1β, IL‐6, and TNFα and was mediated by both CD14+CD16− and CD14+CD16+ monocyte subsets. Despite enhanced cytokine expression, cells maintained their CD25+FoxP3+CD39+ Treg cell phenotype and showed an enhanced capacity to suppress T cell proliferation and IL‐17 production.

Conclusion

Treg cells exposed to a proinflammatory environment show increased cytokine expression as well as enhanced suppressive activity.

     

Reduction of chemokine levels and leukocyte traffic to joints by tumor necrosis factor alpha blockade in patients with rheumatoid arthritis

OBJECTIVE: To verify the hypothesis that in rheumatoid arthritis (RA), tumor necrosis factor alpha (TNFalpha) plays a critical role in regulating leukocyte trafficking and chemokine levels. METHODS: Ten patients with longstanding RA received a single 10 mg/kg infusion of anti-TNFalpha monoclonal antibody (cA2). The articular localization of autologous granulocytes, separated in vitro and labeled with 111In, was studied by analysis of gamma-camera images both before and 2 weeks after treatment. At the same sequential time points, synovial biopsy samples were assessed for infiltrating CD3+ T cells, CD22+ B cells, and CD68+ macrophages. Synovial tissue expression of the chemokines interleukin-8 (IL-8), monocyte chemotactic protein 1 (MCP-1), macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, Groalpha, and RANTES was also determined. Serum IL-8 and MCP-1 concentrations were measured by enzyme-linked immunosorbent assay. RESULTS: Anti-TNFalpha therapy in RA significantly reduced 111In-labeled granulocyte migration into affected joints. There was a simultaneous and significant reduction in the numbers of infiltrating synovial CD3+ T cells, CD22+ B cells, and CD68+ macrophages and in the expression of IL-8 and MCP-1, with a trend toward a reduction in serum concentrations of these chemokines. CONCLUSION: TNFalpha blockade reduces synovial expression of the chemokines IL-8 and MCP-1 and diminishes inflammatory cell migration into RA joints.     

Type 2 diabetes mellitus metabolic control correlates with the phenotype of human monocytes and monocyte-derived macrophages

AimsMonocytes and macrophages express cell-surface markers indicative of their inflammatory and activation status. In this study, we investigated whether these markers are affected or correlated in non-obese T2D subjects, or glycemic/metabolic control variables.MethodsClinical data was recorded, and peripheral blood drawn from T2D patients (n = 28) and control subjects (n = 27). Isolated monocytes were evaluated by flow cytometry for the expression of CD14, CD16, and the phenotypic markers for the different states of activation spectrum, such as pro-inflammatory (M1) (HLA-DR, CD86), anti-inflammatory/pro-resolving (M2) (CD163, CD206, MERTK, PD-L1) and metabolically-activated (MMe) (CD36, ABCA-1). From a subset of individuals, monocytes-derived macrophages (MDM) were obtained and evaluated for phenotypic markers. A correlation analysis was performed between the clinical variables and the marker expression.ResultsThe frequency of CD14⁺⁺CD16⁻ monocytes was lower in T2D patients and it correlates negatively with poor control in glycemic and metabolic variables. T2D monocytes expressed lower levels of HLA-DR, CD86, PD-L1, and CD163, which correlated negatively with poor metabolic control. In MDM from T2D patients, HLA-DR, CD86 and CD163 expression was lower and it inversely correlated with deficient glycemic or metabolic control parameters.ConclusionThe glycemic/metabolic control associated with T2D influences monocyte and MDM phenotypes toward an immune-suppressive phenotype.     

Successful HAART is associated with high B-chemokine levels in chronic HIV type 1-infected patients

Chemokine receptors are used by HIV-1 for entry into CD4+ T cells. The beta-chemokines are capable of inhibiting HIV replication. This study measured beta-chemokine macrophage inflammatory protein (MIP)-1alpha and MIP-1beta levels and determined the CCR5 and CXCR4 expression on T cells in HIV-1-infected patients treated with HAART. The time of known HIV infection and time of HAART use were similar between failure and successful groups. The CD4+ T cell nadir was 163 vs. 251 cells/mm3, p = 0.07, for failure and successful groups, respectively. The successfully treated group, when compared with the failure group, had a higher median CD4+ T cells count (667 vs. 257 cells/mm3; p = 0.003) as well as higher spontaneous MIP-1alpha (median of 4390 vs. 802 pg/ml, p = 0.03) and MIP-1beta (median of 2416 vs. 1117 pg/ml, p = 0.001) levels. The untreated patients had a higher number and intensity of CCR5- and CXCR4-expressing T cells. Higher levels of chemokines were not related to nadir CD4+ T and current CD8+ T cell counts. Successfully treated patients were able to produce higher amounts of beta-chemokines and normalize the coreceptor overexpression on T cells. These findings may have clinical implications, such as a new strategy of using chemokines as adjuvants in anti-HIV therapy.     

依那西普治疗降低强直性脊柱炎外周血T细胞活性

目的 研究肿瘤坏死因子(TNF)-α抑制剂依那西普(Etanercepl)对强直性脊柱炎(AS)患者外周血T细胞活性的影响.方法 10例健康志愿者,40例活动性AS患者,随机给予依那西普(50 mg,皮下注射,每周1次)或安慰剂治疗,治疗前后分离外周血单个核细胞(PBMC),酶联免疫斑点法(ELISPOT)分别检测分泌TNF-α、白细胞介素(IL)-2、干扰素(IFN)-γ的细胞数量.WST-1法检测T细胞增殖.结果 依那西普治疗后,分泌TNF-α的单核细胞数量减少;抗CD3和抗CD28抗体刺激后,分泌IL-2和IFN-γ的T细胞数量减少.CD4+/CD8+T细胞增殖没有明显变化.结论 抗TNF-α的治疗降低了AS患者外周血T细胞的活性,改善了AS患者病情.     

Fas signal links innate and adaptive immunity by promoting dendritic-cell secretion of CC and CXC chemokines

Dendritic cells (DCs) and chemokines are important in linking innate and adaptive immunity. We previously reported that Fas ligation induced interleukin 1beta (IL-1beta)-dependent maturation and IL-1beta-independent survival of DCs, with extracellular signal-regulated kinase (ERK) and nuclear factor-kappaB (NF-kappaB) signaling pathways involved, respectively. We describe here that Fas ligation induced DCs to rapidly produce both CXC and CC chemokines, including macrophage inflammatory protein 2 (MIP-2), MIP-1alpha, MIP-1beta, monocyte chemoattractant protein 1 (MCP-1), RANTES (regulated on activation normal T cell expressed and secreted), and TARC (thymus and activation-regulated chemokine), resulting in enhanced chemoattraction of neutrophils and T cells by Fas-ligated DCs in vivo or by its supernatant in vitro. These chemokines work synergistically in chemoattraction of neutrophils and T cells with MIP-2 more important for neutrophils, MIP-1alpha and TARC more important for T cells. Moreover, Fas-ligated DCs increased endocytosis by neutrophils and activation and proliferation of antigen-specific naive T cells. Fas ligation-induced DC secretion of chemokines involves Ras/Raf/mitogen-activated protein kinase kinase (MEK)/ERK activation and is ERK, but not NF-kappaB, dependent. Activation of caspases, including caspase 1, but not IL-1 autocrine action, is involved in this process. These data indicate that Fas signaling provides a key link between innate response and adaptive immunity by promoting DC chemokine production.     

Chemokine expression and leucocyte infiltration in Sjogren's syndrome

OBJECTIVE: To investigate the expression and source of chemokines in minor salivary gland biopsies (MSGs) in patients with Sjogren's syndrome (SS). METHODS: Immunohistochemical analysis was used to determine the pattern of chemokine expression in MSGs from patients with (n=6) and without (n=5) SS, as well as to examine the phenotype of both resident and infiltrating cells expressing chemokines. RESULTS: Significant differences in the number of infiltrating mononuclear (MN) cells in patients with and without SS were noted. Ductal epithelial cells of SS biopsies expressed significantly increased levels of macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, interleukin-8 (IL-8) and RANTES (Regulated upon Activation, Normal T cell Expressed and Secreted). Biopsies from patients with SS showed that MIP-1beta was expressed by 51% of infiltrating cells, while 41% expressed MIP-1alpha, whereas 22 and 7% expressed RANTES and IL-8, respectively. CONCLUSION: Chemokines expressed by ductal epithelial cells may attract circulating leucocytes, in particular CD4+ T cells, towards the site of inflammation, thereby orchestrating the influx of MN cells characteristically seen in MSGs in SS. Chemokines may be induced directly by a putative triggering agent for SS, or secondary to the release of pro-inflammatory cytokines produced by epithelial cells. These findings further implicate epithelial cells as playing a major role in the pathogenesis of SS and implicate chemokines in the leucocyte recruitment in this setting.      

Differential expression of chemokine receptors on peripheral blood, synovial fluid, and synovial tissue monocytes/macrophages in rheumatoid arthritis

OBJECTIVE: Since it is likely that monocytes utilize chemokines to migrate to the rheumatoid arthritis (RA) joint, we investigated the expression of C-C chemokine receptors (CCR) 1-6 and C-X-C receptor 3 (CXCR3) in the peripheral blood (PB), synovial fluid (SF), and synovial tissue of patients with RA as well as in the PB of normal subjects. METHODS: We compared chemokine receptor expression on CD14+ monocytes from normal PB, RA PB, and RA SF using 2-color flow cytometry. Correlations with patient clinical data were determined. Chemokine and receptor expression were investigated in RA synovial tissue by immunohistochemistry and 2-color immunofluorescence to identify CD68+ macrophages. RESULTS: Most normal PB monocytes expressed CCR1 (87%) and CCR2 (84%), but not CCRs 3, 4, 5, or 6 or CXCR3. RA PB monocytes expressed CCR1 (56%) and CCR2 (76%), with significantly more expressing CCR3 (18%), CCR4 (38%), and CCR5 (17%) compared with normal PB monocytes. Significantly fewer SF monocytes from RA patients expressed CCR1 (17%), CCR2 (24%), and CCR4 (6%) while significantly more expressed CCR3 (35%) and CCR5 (47%) compared with RA and normal PB monocytes; CCR6 and CXCR3 were rarely detected. Clinically, the erythrocyte sedimentation rate was inversely correlated with the expression of CCR1 and CCR4 by RA PB, and CCR5 expression by RA SF was correlated with the SF white blood cell count. CCR1-, CCR2-, and CCR5-immunoreactive cells were found in RA synovial tissue and colocalized with CD68+ macrophages. RA synovial tissue RANTES (regulated upon activation, normally T cell expressed and secreted chemokine)- and monocyte chemoattractant protein 1-immunoreactive cells colocalized with CCR1 and CCR2, respectively, on serial sections. Macrophage inflammatory protein 1alpha (MIP-1alpha) was principally restricted to vascular endothelium, and MIP-1beta+ macrophages were found throughout the sections. CONCLUSION: Monocytes mainly express CCR1 and CCR2 in normal and RA PB, CCR3 and CCR5 in RA PB and RA SF, and CCR4 in RA PB. The differential expression of chemokine receptors suggests that certain receptors aid in monocyte recruitment from the circulation while others are important in monocyte retention in the joint.