Excessive ADAM17 activation occurs in uremic patients and may contribute to their immunocompromised status.

INTRODUCTION: We previously reported that fibroblast growth factor 23 (FGF23)-klotho signaling plays a role in B cell immunity. Despite high serum levels of FGF23, a decline in immunity is frequently observed in patients on hemodialysis (HD); thus, abnormalities in the FGF23-klotho signaling pathway in immune cells may occur in these patients. METHODS: We analyzed the number of klotho-positive cells in peripheral blood mononuclear cells from 10 male and 6 female patients on HD and 5 healthy male subjects using flow cytometry. We analyzed the abundance of cleaved klotho protein in the murine B cell line, A20, and in the serum of HD patients and healthy subjects (HS) using flow cytometry and Western blotting. The serum level of A disintegrin and metalloprotease 17 (ADAM17) was measured in HD patients and HS using enzyme-linked immunosorbent assay. RESULTS: The number of klotho-positive B cells was reduced in HD patients. Serum ADAM17 was responsible for the reduction in klotho, as a specific ADAM17 inhibitor reversed this change. The total serum levels of ADAM17 were similar in HD patients and HS; however, activated ADAM17 was increased in the serum of HD patients. CONCLUSIONS: We concluded that abnormal ADAM17 activation could contribute to the immunocompromised status in patients on HD, in line with the reported role of ADAM17 as an anti-inflammatory and immunosuppressive factor.

Correlation between haemoglobin level and type of erythropoiesis-stimulating agent at initiation of haemodialysis.

Background Renal anaemia worsens because of the uraemic status immediately before the initiation of haemodialysis. The haemoglobin level in patients with chronic kidney disease is correlated with cardiovascular disease and mortality. Objective This study was performed to determine whether short- and long-acting erythropoiesis-stimulating agents are correlated with the pre-haemodialysis haemoglobin level in patients with chronic kidney disease. Setting This study was conducted at the Blood Purification Center in Wakayama Medical University. Method We enrolled 364 patients undergoing initiation of haemodialysis from January 2009 to June 2015 and analysed them for > 3 months prior to the initiation of haemodialysis. In total, 168 patients were included in the final analysis based on the inclusion and exclusion criteria. Main outcome measures The correlation of the haemoglobin level at the initiation of haemodialysis with various factors according to the type of erythropoiesis-stimulating agent used. Results The median haemoglobin level was 8.8 g/dL, and long-acting erythropoiesis-stimulating agents were used by 69.6% of the patients. Long-acting erythropoiesis-stimulating agents were used significantly more often in patients with high than low haemoglobin levels. The haemoglobin levels at the initiation of haemodialysis and 1 month prior tended to be significantly higher in patients taking long-than short-acting erythropoiesis-stimulating agents. The serum levels of iron and albumin and the use of long-acting erythropoiesis-stimulating agents were independently correlated with the haemoglobin level at the initiation of haemodialysis in the multivariate regression analysis. In addition, the left ventricular mass index was significantly correlated with the haemoglobin level at the initiation of haemodialysis. Conclusion Long-acting erythropoiesis-stimulating agents were correlated with higher haemoglobin levels and may be more useful for patients with a low left ventricular mass index at the initiation of haemodialysis.

Severe refractory infection due to renocolic fistula in a patient with a giant kidney and ADPKD undergoing long-term hemodialysis.

Renocolic fistula is rare. Renal cyst infection is a serious complication in patients with autosomal dominant polycystic kidney disease (ADPKD). We present a case of refractory renal cyst infection due to renocolic fistula in a patient with ADPKD. A 65-year-old man with ADPKD on hemodialysis visited our hospital with complaints of fever and left abdominal pain. We diagnosed renal cyst infection with abdominal computed tomography scans. After hospitalization, gas shadow was observed in the left renal cyst. Percutaneous puncture of the cyst was performed. Because contrast medium into the left renal cyst through nephrostomy was flowing into the descending colon, renocolic fistula was diagnosed. The patient underwent nephrectomy combined with partial descending colonic resection and splenectomy, but he died. Renocolic fistula is probably hidden in some refractory renal cyst infection cases. This case report aims to create awareness of renocolic fistula, so that early diagnosis and intervention can salvage such patients.

Magnesium prevents phosphate-induced vascular calcification via TRPM7 and Pit-1 in an aortic tissue culture model.

Previous clinical and experimental studies have indicated that magnesium may prevent vascular calcification (VC), but mechanistic characterization has not been reported. This study investigated the influence of increasing magnesium concentrations on VC in a rat aortic tissue culture model. Aortic segments from male Sprague-Dawley rats were incubated in serum-supplemented high-phosphate medium for 10 days. The magnesium concentration in this medium was increased to demonstrate its role in preventing VC, which was assessed by imaging and spectroscopy. The mineral composition of the calcification was analyzed using Fourier transform infrared (FTIR) spectroscopic imaging, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) mapping. Magnesium supplementation of high-phosphate medium dose-dependently suppressed VC (quantified as aortic calcium content), and almost ablated it at 2.4 mm magnesium. The FTIR images and SEM-EDX maps indicated that the distribution of phosphate (as hydroxyapatite), phosphorus and Mg corresponded with calcium content in the aortic ring and VC. The inhibitory effect of magnesium supplementation on VC was partially reduced by 2-aminoethoxy-diphenylborate, an inhibitor of TRPM7. Furthermore, phosphate transporter-1 (Pit-1) protein expression was increased in tissues cultured in HP medium and was gradually-and dose dependently-decreased by magnesium. We conclude that a mechanism involving TRPM7 and Pit-1 underpins the magnesium-mediated reversal of high-phosphate-associated VC.

Effects of Cyclophosphamide Pulse Therapy on the Clinical and Histopathological Findings, Particularly Crescent Formation, in a Patient with Adult-onset Steroid-refractory Henoch-Schönlein Purpura Nephritis.

A 29-year-old woman was diagnosed with Henoch-Schönlein purpura nephritis (HSPN) based on the presence of purpura and histopathological findings showing crescent formation, mesangial proliferation and IgA deposition in the glomerular mesangium. She was treated with high-dose steroids; however, the nephritic syndrome persisted. Therefore, we diagnosed her with steroid-resistant HSPN and decided to add treatment with cyclosphamide pulse therapy. After one year of treatment, the histopathological findings, including crescent formation and IgA deposition, improved, as confirmed on a renal biopsy, and the patient fulfilled the criteria for complete remission. Cyclophosphamide pulse therapy may be considered an effective treatment for intractable HSPN.

The management of hyperphosphatemia by lanthanum carbonate in chronic kidney disease patients.

Hyperphosphatemia has been shown to be involved not only in the onset and progression of secondary hyperparathyroidism but also in vascular calcification. In addition, it influences the clinical course of patients with chronic kidney disease. Phosphate (Pi) binder is required in the management of hyperparaphosphatemia, because dietary Pi restriction and Pi removal by hemodialysis alone are insufficient. Lanthanum carbonate, a powerful Pi binder, has a similar effect to aluminum hydroxide in reducing serum Pi levels. As it is excreted via the liver, lanthanum carbonate has an advantage in patients with renal failure. The effect of lanthanum carbonate on serum Pi levels is almost two times higher than that of calcium (Ca) carbonate, which is commonly used. Lanthanum carbonate and Ca carbonate have an additive effect. Worldwide, there is 6 years worth of clinical treatment data on lanthanum carbonate; however, we have 3 years of clinical use in Japanese patients with hyperphosphatemia. No serious side effects have been reported. However, the most important concern is bone toxicity, which has been observed with use of aluminum hydroxide. For this study, clinical research involved analysis of bone biopsies. Although osteomalacia is the most noticeable side effect, this was not observed. Both the high- and the low-turnover bone disease concentrated into a normal bone turnover state. However, as the authors have less than 10 years' clinical experience with lanthanum carbonate, patients should be monitored carefully. In addition, it is necessary to demonstrate whether potent treatment effects on hyperphosphatemia improve the long-term outcome.

Effect of interleukin-6 receptor blockage on renal injury in apolipoprotein E-deficient mice.

Hyperlipidemia has been demonstrated to be associated with renal disease, yet the mechanism of renal injury is still poorly understood. Inflammation that occurs with the hyperlipidemia has been considered to play an important role in development of glomerular injury. In the present study, we investigated the role of interleukin-6 (IL-6), a key inflammatory molecule, on renal injury in apolipoprotein E-deficient (ApoE(-/-)) mice with severe hypercholesterolemia. The 6-wk-old mice were fed a high-fat diet and administered weekly rat anti-IL-6 receptor monoclonal antibody (MR16-1), control rat IgG, or saline for a total of 4 wk. We examined histopathological changes in the kidney and urinary excretion of protein and albumin. Saline- and IgG-treated mice showed remarkable proteinuria at 10 wk of age, whereas MR16-1-treated mice exhibited significantly lower levels. Renal histopathology of saline- and IgG-treated mice revealed striking lipid deposits and foam cells in the glomerular tuft, juxtaglomerular area, and arteriolar wall along with range of mesangial cell proliferation and matrix expansion. Notably, the severity of lipid deposits and mesangial cell proliferation were significantly reduced in MR16-1-treated mice. Immunohistochemistry demonstrated that mesangial IL-6 expression was dramatically reduced in MR16-1-treated mice compared with IgG-treated mice. Blocking the IL-6 receptor prevented progression of proteinuria and renal lipid deposit, as well as the mesangial cell proliferation associated with severe hyperlipoproteinemia. These results clearly demonstrate that IL-6 plays an essential role in the pathogenesis of hyperlipidemia-induced glomerular injury in ApoE(-/-) mice and suggests the usefulness of anti-IL-6 receptor antibody in treatments for hyperlipidemia-induced organ damage.

Clinical value of blocking IL-6 receptor.

PURPOSE OF REVIEW: Interleukin-6 (IL-6) is a multifunctional cytokine that regulates inflammatory response and immune reaction. Overproduction of IL-6 is pathologically involved in inflammatory autoimmune diseases such as rheumatoid arthritis (RA) and juvenile idiopathic arthritis, and therefore, blocking IL-6 activity is one of therapeutic options for these diseases. Tocilizumab is a humanized anti-IL-6 receptor (IL-6R) antibody and inhibits IL-6 activity. There is now accumulating evidence that tocilizumab is therapeutically effective for patients with RA and other inflammatory autoimmune diseases. This article reviews the clinical value of blocking IL-6R. RECENT FINDINGS: Tocilizumab, as monotherapy and in combination with methotrexate, has been shown to be effective for RA patients with insufficient efficacy to methotrexate or other disease-modifying antirheumatic drugs. These findings of tocilizumab have been expanded to patients refractory to tumor necrosis factor inhibitors. Tocilizumab also retards the progression of structural joint damage. Furthermore, a 5-year long-term safety and efficacy has been shown. Tocilizumab is also a promising therapeutic option for other rheumatic diseases such as systemic-onset juvenile idiopathic arthritis, adult-onset Still's disease, and Takayasu arteritis. SUMMARY: Blocking IL-6R with tocilizumab represents a promising new treatment for RA and other inflammatory diseases. Large registry data will warrant the safety profile of tocilizumab.

Interactions among type I and type II interferon, tumor necrosis factor, and beta-estradiol in the regulation of immune response-related gene expressions in systemic lupus erythematosus.

INTRODUCTION: Systemic lupus erythematosus (SLE) is a prototypical autoimmune disease characterized by various clinical manifestations. Several cytokines interact and play pathological roles in SLE, although the etiopathology is still obscure. In the present study we investigated the network of immune response-related molecules expressed in the peripheral blood of SLE patients, and the effects of cytokine interactions on the regulation of these molecules. METHODS: Gene expression profiles of peripheral blood from SLE patients and from healthy women were analyzed using DNA microarray analysis. Differentially expressed genes classified into the immune response category were selected and analyzed using bioinformatics tools. Since interactions among TNF, IFNgamma, beta-estradiol (E2), and IFNalpha may regulate the expression of interferon-inducible (IFI) genes, stimulating and co-stimulating experiments were carried out on peripheral blood mononuclear cells followed by analysis using quantitative RT-PCR. RESULTS: Thirty-eight downregulated genes and 68 upregulated genes were identified in the functional category of immune response. Overexpressed IFI genes were confirmed in SLE patient peripheral bloods. Using network-based analysis on these genes, several networks including cytokines--such as TNF and IFNgamma--and E2 were constructed. TNF-regulated genes were dominant in these networks, but in vitro TNF stimulation on peripheral blood mononuclear cells showed no differences in the above gene expressions between SLE and healthy individuals. Co-stimulating with IFNalpha and one of TNF, IFNgamma, or E2 revealed that TNF has repressive effects while IFNgamma essentially has synergistic effects on IFI gene expressions in vitro. E2 showed variable effects on IFI gene expressions among three individuals. CONCLUSIONS: TNF may repress the abnormal regulation by IFNalpha in SLE while IFNgamma may have a synergistic effect. Interactions between IFNalpha and one of TNF, IFNgamma, or E2 appear to be involved in the pathogenesis of SLE.

Mechanisms and pathologic significances in increase in serum interleukin-6 (IL-6) and soluble IL-6 receptor after administration of an anti-IL-6 receptor antibody, tocilizumab, in patients with rheumatoid arthritis and Castleman disease.

Interleukin-6 (IL-6) plays pathologic roles in immune-inflammatory diseases such as rheumatoid arthritis (RA) and Castleman disease. By inhibiting IL-6 receptors (IL-6Rs), tocilizumab (a humanized anti-IL-6R antibody) ameliorates the symptoms of these diseases and normalizes acute-phase proteins, including C-reactive protein (CRP). We found that tocilizumab treatment increased serum levels of IL-6 and soluble IL-6R (sIL-6R). To investigate the pathologic significance of these increases, we analyzed the kinetics of serum IL-6 and sIL-6R and the proportion of sIL-6R saturated with tocilizumab after tocilizumab administration in patients with RA and Castleman disease and then compared the results with the CRP values. Serum IL-6 and sIL-6R markedly increased after tocilizumab administration in both RA and Castleman disease. As long as free tocilizumab was detectable, sIL-6R was saturated with tocilizumab and IL-6 signaling was completely inhibited. We concluded that it is likely that sIL-6R increased because its elimination half-life was prolonged by the formation of tocilizumab/sIL-6R immune complex, and that free serum IL-6 increased because IL-6R-mediated consumption of IL-6 was inhibited by the unavailability of tocilizumab-free IL-6R. We also concluded that the increased level of free IL-6 during tocilizumab treatment closely reflects the actual endogenous IL-6 production and true disease activity.

RANKL-induced expression of tetraspanin CD9 in lipid raft membrane microdomain is essential for cell fusion during osteoclastogenesis.

UNLABELLED: We showed that CD9, a member of tetraspanin superfamily proteins, is expressed in a specific membrane microdomain, called "lipid raft," and is crucial for cell fusion during osteoclastogenesis after activation of the RANK/RANKL system. INTRODUCTION: Osteoclasts are bone-resorbing multinuclear polykaryons that are essential for bone remodeling and are formed through cell fusion of mononuclear macrophage/monocyte lineage precursors. Although osteoclastogenesis has been shown to be critically regulated by the RANK/RANKL system, the mechanism how precursor cells fuse with each other remains unclear. We examined the function of CD9, a member of tetraspanin superfamily, which has previously been shown to form macromolecular membrane microdomains and to regulate cell-cell fusion in various cell types. MATERIALS AND METHODS: We used RAW264.7, a macrophage/monocyte lineage cell line, which can differentiate into osteoclast-like polykaryons on the application of RANKL. Expression and distribution of CD9 was assessed by Western blotting, fluorescence-assorted cell sorting (FACS) and immunohistochemistry with light and electron microscopy. A specific neutralizing antibody and RNA interference were used to inhibit the function of CD9, and green fluorescent protein (GFP)-CD9 was exogenously expressed to enhance the effect of CD9. The distribution of CD9 in lipid microdomain was examined by biochemical (sucrose density gradient) isolation and imaging technique. RESULTS: CD9 is expressed on cell surfaces of RAW264.7, which is enhanced by RANKL. Targeted inhibition of CD9 decreases the number of osteoclast-like cells. On the other hand, overexpression of CD9 promotes spontaneous cell fusion even in the absence of RANKL. CD9 is localized in detergent-insoluble "lipid raft" microdomain in RANKL stimulation, and disruption of lipid rafts markedly reduces the formation of osteoclast-like polykaryons. Immunohistochemical studies of bone tissues revealed the expression of CD9 in osteoclasts in vivo. CONCLUSIONS: These data suggest that function of tetraspanin CD9 and its expression in lipid rafts are crucial for cell fusion during osteoclastogenesis.

Osteopontin as a positive regulator in the osteoclastogenesis of arthritis.

We examined the role of osteopontin (OPN) in the osteoclastogenesis of arthritis using collagen-induced arthritis (CIA). Cells from arthritic joints of wild-type (OPN +/+) mice spontaneously developed bone-resorbing osteoclast-like cells (OCLs). The cultured cells showed an enhanced expression of receptor activator of nuclear factor kappaB ligand (RANKL) and a decreased expression of osteoprotegerin (OPG). The addition of OPG reduced the number of OCLs, indicating that the osteoclastogenesis depends on the RANK/RANKL/OPG system. The cells also produced OPN abundantly and anti-OPN neutralizing antibodies suppressed the development of OCLs. Moreover, the addition of OPN increased the expression of RANKL and augmented differentiation of OCLs from OPN-deficient (OPN -/-) cells. OPN, like the combination of 1alpha,25-dihydroxyvitamin D(3) and dexamethasone, also enhanced the RANKL expression and decreased OPG expression in a stromal cell line, ST2. These results suggest that OPN acts as a positive regulator in the osteoclastogenesis of arthritis through the RANK/RANKL/OPG system.

Enhanced production of osteopontin in multiple myeloma: clinical and pathogenic implications.

In this study, we examined osteopontin (OPN) production in myeloma cells and plasma OPN levels in multiple myeloma (MM) patients. We assessed OPN production in bone marrow cells (BMCs) by immunocytochemistry and enzyme-linked immunosorbent assay (ELISA). We also assessed OPN production in various B-cell malignant cell lines, including three myeloma cell lines by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting. In addition, we measured plasma OPN concentrations by ELISA in 30 MM patients, 21 monoclonal gammopathy of undetermined significance (MGUS) patients and 30 healthy volunteers. As a result, in an immunocytochemical study, abundant OPN was detected in BMCs from overt MM patients, whereas no OPN was detected in BMCs from patients with other haematological diseases, including MGUS. Cultured BMCs from overt MM patients produced more OPN than those from patients with either smouldering MM or MGUS. Myeloma cell lines spontaneously produced OPN. Plasma OPN levels of MM patients were significantly higher than those of MGUS patients and healthy volunteers (P < 0.05). Moreover, they correlated with both progression and bone destruction of the disease (P < 0.05). These suggest that myeloma cells actively produce OPN, which possibly contributes to osteoclastic bone resorption in MM. Plasma OPN levels may be a useful biomarker for assessing bone destruction in MM and distinguishing MM from MGUS or smouldering MM.

Synergistic effect on the attenuation of collagen induced arthritis in tumor necrosis factor receptor I (TNFRI) and interleukin 6 double knockout mice.

OBJECTIVE: To evaluate any additive effect on attenuation of collagen induced arthritis (CIA) in tumor necrosis factor receptor I (TNFRI) and interleukin 6 (IL-6) double knockout (DKO) mice. METHODS: CIA was induced in wild-type (Wt), TNFRI knockout (TNFRIKO), IL-6 knockout (IL-6KO), and DKO mice. Comparative studies were performed among these different mouse genotypes observing clinical (incidence, arthritis score), histological, radiologic, and immunological aspects. RESULTS: More than 90% of the Wt, TNFRIKO, and IL-6KO mice developed definite CIA, while only 20% of the DKO mice did so. Severity of arthritis, indicated by the arthritis score, was significantly reduced in both the TNFRIKO and IL-6KO mice compared with the Wt mice. Moreover, the severity of arthritis in the DKO mice was significantly reduced compared with each single KO mouse (by arthritis scores; DKO vs TNFRIKO, IL-6KO mice, p < 0.05). In addition, histological and radiologic changes were also significantly reduced in the DKO mice compared with each single KO mouse (by histological and radiologic scores; DKO vs TNFRIKO, IL-6KO mice, p < 0.05 and p < 0.01 respectively). In immunological studies, serum anti-type II collagen (anti-CII) antibody concentrations were significantly decreased in the DKO mice compared with each single KO mouse (DKO vs TNFRIKO, IL-6KO mice, p < 0.01). CONCLUSION: Simultaneous blockade of TNFRI and IL-6 showed synergistic rather than additive effects on the attenuation of CIA. Combinations of anti-TNF-a and anti-IL-6 therapy may provide clinical benefits for treatment of rheumatoid arthritis compared with therapy against each single cytokine.

Enhanced local production of osteopontin in rheumatoid joints.

OBJECTIVE: To investigate the involvement of osteopontin (OPN) in the pathogenesis of rheumatoid arthritis (RA), localization and production of OPN were examined in patients with RA. METHODS: Localization of OPN in the rheumatoid synovium was examined by immunohistochemistry. In vitro OPN production by cultured synovial cells from patients with RA (n = 5) and with osteoarthritis (OA) (n = 5) was assessed by ELISA. OPN concentrations in plasma and synovium were quantified in patients with RA (n = 23) by 2 distinct ELISA systems to measure both thrombin cleaved and non-cleaved OPN. The same experiments were done in patients with OA (n = 15) and healthy volunteers (n = 10) as a control. RESULTS: OPN was highly detected by immunohistochemistry predominantly in the RA synovial lining cells, while less and scattered OPN was detected in OA synovial tissues. ELISA revealed that cultured RA synovial cells secreted significantly more OPN than OA cells. ELISA also showed a marked increase of OPN levels in synovial fluid (SF) of patients with RA and with OA compared to the control plasma OPN levels, although OPN levels were not increased in RA and OA plasma compared to healthy controls. SF OPN levels of patients with RA were significantly higher than those of patients with OA, and correlated with serum C-reactive protein levels. The ratios of thrombin cleaved versus non-cleaved OPN were significantly increased in RA plasma and SF compared with OA plasma and SF and plasma from healthy controls. CONCLUSION: Our results revealed enhanced local production of OPN in rheumatoid joints, suggesting involvement of OPN in the pathogenesis of RA.

A possible mechanism of NK cell-lineage granular lymphocyte proliferative disorder (NK-GLPD) in a patient with chronic active Epstein-Barr virus infection (CAEBV) and severe hypersensitivity to mosquito bites (SHMB).

We report the case of a young female patient with chronic active Epstein-Barr virus infection (CAEBV) and severe hypersensitivity to mosquito bites (SHMB). She showed a marked increase of NK cell population in peripheral blood. The NK cell population was suggested to be infected with EBV, and to be oligoclonal by Southern blotting using an EBV genome terminal-repeat probe. The NK cells aberrantly expressed CD25, a high affinity receptor for IL-2, and showed an augmented in vitro proliferative response to IL-2. Moreover, they also showed enhanced expression of both Fas-ligand and Bcl-2, and resistance to in vitro Fas-induced apoptotic cell death (Fas-ACD). Taken together, these observations suggested that both the augmentation of proliferative response to IL-2 and the decrease in Fas-ACD may cause NK cell lineage granular lymphocyte proliferative disorder (NK-GLPD) in patients with CAEBV and SHMB.

Antigen induced arthritis (AIA) can be transferred by bone marrow transplantation: evidence that interleukin 6 is essential for induction of AIA.

OBJECTIVE: To investigate the role of bone marrow cells (BMC) in the induction of antigen induced arthritis (AIA), the expression of 3 major proinflammatory cytokines, interleukin 1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and IL-6, was examined in the bone marrow (BM) of mice with AIA. We also examined whether AIA could be transferred by bone marrow transplantation (BMT). METHODS: Expression of IL-1beta, TNF-alpha, and IL-6 in BMC was assessed by immunohistochemistry throughout the course of AIA. BMT experiments were performed using 2 different mouse genotypes, wild type (IL-6+/+) and IL-6 deficient (IL-6-/-) mice, as a donor. The gradation of AIA was evaluated histologically. RESULTS: IL-6 was highly expressed in the BM at induction as well as during progression of AIA, while TNF-alpha showed a marginal expression, and no significant expression of IL-1beta was detected throughout the course of AIA. In BMT experiments, all irradiated IL-6+/+ mice developed typical AIA by transplantation of BMC from immunized IL-6+/+ mice, whereas almost no irradiated IL- 6+/+ mice transplanted with BMC from the immunized IL-6-/- mice developed definite arthritis. CONCLUSION: These results suggest that BMC play a critical role and IL-6 is a key cytokine for the induction and progression of AIA. There may be clinical benefits in the blockade of IL-6 and BMT in the treatment of rheumatoid arthritis.

Expansion of a CD28-intermediate subset among CD8 T cells in patients with infectious mononucleosis.

Infectious mononucleosis (IM) is an acute sporadic infection that usually affects young adults, and during infection a massive expansion of CD8 T cells is generally considered to occur. However, CD28 expression of the expanded cells has not been characterized. When peripheral blood mononuclear cells of acute IM (AIM) patients were analyzed by flow cytometry, a continuous spectrum of CD28 intensity ranging from negative to high, which could be separated into CD28 negative, intermediate (int), and positive, was seen for CD8 T cells. We studied 26 IM patients who were diagnosed on the basis of standard methods and found that all patients had the continuous CD28 spectrum. CD28 is a costimulatory molecule on T cells, and its expression is associated with the subdivision of CD8 cells into cytotoxic (CD28-positive) and suppressor (CD28-negative) T cells. After 24 h of ex vivo culturing, however, the continuous spectrum was found to consist of only CD28-positive and CD28-negative CD8 T cells, because the CD28-int cells had disappeared due to apoptosis. The CD28-int T cells have several cytotoxic functions, suggesting that CD28-int T cells are effectors. Examination of other costimulatory markers in AIM patients showed that CD80 and CD152 were not affected. In patients with other viral infections, such as measles or rubella, however, the continuous spectrum was not detected. These results suggest that there is an unusual CD28 expression pattern in patients with AIM, namely, the presence of a functional CD28-int subset among CD8 T cells. These findings are of special importance for clarifying the defense mechanism against Epstein-Barr virus infection, and the role of CD28 molecules in humans and should also be helpful for the diagnosis of AIM.