Performance Evaluation of the CRE2 Reagent from Siemens for Serum Creatinine Measurement

BACKGROUND: For creatinine measurement, the enzymatic method is known to be more accurate than the Jaffe method; however, the latter is still widely used. We evaluated the performance of the CRE2 reagent (Siemens Healthcare Diagnostics Inc., USA), which uses a modified Jaffe method. METHODS: Three quality control standards were used for precision evaluations of CRE2 on Dimension VISTA 500 instrument (Siemens). Moreover, the linearity and carryover characteristics were assessed. Sixty-eight creatinine results obtained using the CRE2 and ECREA (enzymatic) reagents (Siemens) were compared with those obtained using the L-CRE (enzymatic) reagent (Shinyang Diagnostics, Korea). The accuracy of CRE2, ECREA, and L-CRE was evaluated using a standard reference material. RESULTS: The CV of within-run (0.7–2.4%), between-run (0.4–1.7%), between-day precision (0.7–0.9%) for three standards, and total CV for medium (1.6%) and high levels (1.3%) satisfied the analytical goal. The linearity for CRE2 was excellent (R2=0.999). Comparisons of CRE2 and ECREA to L-CRE were well correlated (r=0.996 and 0.997, respectively). In comparison with L-CRE, 5 CRE2 results and 15 ECREA results exceeded minimum bias goal (5.1%) in samples with creatinine levels of >1 mg/dL. The carryover rate was −0.04%. In terms of accuracy, the percent bias values of CRE2, ECREA, and L-CRE were 7.4, −6.4, and −3.4, respectively, for low level; and 3.9, −1.5, and 0.7, respectively, for high level. CONCLUSIONS: For creatinine measurements, the CRE2 reagent showed good performance. It can be used in the diagnosis, treatment monitoring, and risk assessment of kidney diseases.

The prognostic impact of lymphocyte subsets in newly diagnosed acute myeloid leukemia

BACKGROUND: Tumor-infiltrating lymphocytes, which form a part of the host immune system, affect the development and progression of cancer. This study investigated whether subsets of lymphocytes reflecting host-tumor immunologic interactions are related to the prognosis of patients with acute myeloid leukemia (AML). METHODS: Lymphocyte subsets in the peripheral blood of 88 patients who were newly diagnosed with AML were analyzed by quantitative flow cytometry. The relationships of lymphocyte subsets with AML subtypes, genetic risk, and clinical courses were analyzed. RESULTS: The percentages of T and NK cells differed between patients with acute promyelocytic leukemia (APL) and those with AML with myelodysplasia-related changes. In non-APL, a high proportion of NK cells (>16.6%) was associated with a higher rate of death before remission (P=0.0438), whereas a low proportion of NK cells (≤9.4%) was associated with higher rates of adverse genetic abnormalities (P=0.0244) and relapse (P=0.0567). A multivariate analysis showed that the lymphocyte subsets were not independent predictors of survival. CONCLUSION: Lymphocyte subsets at diagnosis differ between patients with different specific subtypes of AML. A low proportion of NK cells is associated with adverse genetic abnormalities, whereas a high proportion is related to death before remission. However, the proportion of NK cells may not show independent correlations with survival.

The Usefulness of Hematological Parameters for Assessing Disease Progression in Patients with HIV Infection

BACKGROUND: In patients with HIV, CD4+ T cell count and viral load are the main laboratory tests performed to assess clinical management. However, they require extensive resources. In this study, we aimed to determine whether hematological parameters measured using a hematology analyzer are useful as surrogate markers of CD4+ T cell count and viral load in HIV-infected patients. METHODS: Peripheral blood samples were obtained from 14 HIV-naïve, 105 HIV-treated, and 103 uninfected individuals. Hematological parameters were measured using the ADVIA 2120i hematology analyzer (Siemens Healthcare Diagnostics, USA). RESULTS: In HIV-naïve and -treated patients, the percentage of large unstained cells (%LUCs) was 2.5±1.6% and 1.9±0.7%, respectively, compared to 1.6±0.5% in HIV-uninfected controls. The %LUCs was higher in HIV patients with low CD4⁺ T cell count below 200/μL (2.4±1.0%) or high viral load ≥200 copies/mL (2.4±0.8%) than in other infected groups. Significant differences in lymphocyte count were observed between the HIV-naïve (1.5±0.6×10⁹/L) and uninfected (2.0±0.6×10⁹/L) groups as well as between HIV patients with CD4⁺ T cells ≥500/μL (2.5±0.6×10⁹/L) and other infected groups. Neutrophil count varied between high viral load (3.0±1.4×10⁹/L) and low viral load (3.7±1.3×10⁹/L) groups. The CD4⁺ T cell count correlated with lymphocyte count (r=0.642, P<0.0001) and %LUCs (r=-0.287, P=0.002). CONCLUSIONS: %LUCs, lymphocyte count, and neutrophil count are probable surrogate markers of CD4⁺ T cells and viral load.

Evaluation of Automated Specimen Inoculation for Blood Culture Samples by Use of the Previ Isola(R) System Compared with the Manual Method

BACKGROUND: Recently, a new automated inoculating instrument, Previ Isola(R) (bioMerieux, France) was introduced. Although there are many evaluation reports about the inoculation of urine and body fluid samples using Previ Isola(R), no evaluation has been reported for blood samples. The objectives of this study were to evaluate this instrument for the inoculation of blood samples and to compare the microbiological results with the manual loop-to-plate method. METHODS: From March 2014 to July 2014, a total of 296 non-duplicate blood samples showing positive signals on the BacT/Alert 3D system were obtained, and both manual and automated methods were used for sample inoculation. Results of the two methods were compared according to five aspects: the culture result, number of single colonies, morphology of colonies, number of re-inoculations, and time required for inoculation. RESULTS: The sensitivity and specificity of Previ Isola(R) were 98.9% and 96.6%, respectively. The positive and negative predictive values were 99.6% and 90.3%, respectively, and the total concordance rate was 98.6%. For Previ Isola(R) and the manual methods, the number of average usable single colonies per plate was 25 and 16, the number of re-inoculations was 60 and 62, and the inoculation time for 15 blood samples was 30 min and 75 min, respectively. The morphology of colonies showed no differences between the two methods. CONCLUSIONS: The automated inoculation instrument, Previ Isola(R), showed relative good concordance with manual method, with high sensitivity and high specificity for blood sample inoculation. Previ Isola(R) may be useful for inoculating specimens including blood samples.

A Case of Roseomonas Infection in Korea

Roseomonas is a genus of pink-pigmented, oxidative, gram-negative coccobacilli and rarely causes opportunistic infection. We report a case of wound infection by Roseomonas species in a 53-yr-old man with alcoholic liver cirrhosis. 16S ribosomal RNA (rRNA) gene sequencing was performed to confirm the infectious agent. The patient recovered without complication after ciprofloxacin treatment. To the best of our knowledge, this is the first case of Roseomonas infection reported in Korea.

Association between Glycemic Control and Hematologic Indices in Type 2 Diabetic Patients

BACKGROUND: Diabetes mellitus (DM) is characterized by impaired glucose regulation and various complications. It is known that chronic inflammation and platelet activation play a role in development of insulin resistance or diabetic complications. This study investigated whether hematologic parameters are useful for monitoring blood glucose regulation or complications in DM patients. METHODS: Total 90 diabetic patients were divided into two groups according to their hemoglobin A1c (HbA1c) levels: 59 regulated DM patients with HbA1c levels<7% and 31 unregulated DM patients with HbA1c levels≥7%. RESULTS: White blood cell counts (P=0.021), neutrophil counts (P=0.005), monocyte counts (P=0.040), neutrophil % (P=0.042) and the neutrophil lymphocyte ratio (NLR) (P=0.032) were significantly higher in the unregulated DM group compared to that in the regulated DM group. There were no differences in lymphocyte counts, lymphocyte %, monocyte %, mean neutrophil volume, mean monocyte volume, platelet count, and mean platelet volume between groups. Neutrophil counts and NLR were higher in unregulated DM patients with complications than in the regulated DM group. A positive correlation was observed between HbA1c and white blood cell count (r=0.389, P<0.001) and neutrophil count (r=0.361, P<0.001). CONCLUSIONS: In DM patients, neutrophil counts and NLR were related to glycemic control and the presence of complications. Additionally, neutrophil counts showed a positive correlation with HbA1c. Therefore, neutrophil counts and NLR can be used as related markers for diabetic regulation and complications during the follow-up of diabetic patients.

Annual Report on the External Quality Assessment for Diagnostic Hematology in Korea (2015)

During 2015, the Diagnostic Hematology Subcommittee of Korean Association of External Quality Assessment Service performed laboratory proficiency testing for blood cell count, cell morphology, and coagulation tests. Four trials for blood cell count and cell morphology tests each and two trials for coagulation tests were performed. The trials for blood cell counts had a reply rate of 97.2% among 1,352 laboratories, compared to 99.0% among 503 laboratories for cell morphology and 98.6% among 574 laboratories for coagulation tests. The homogeneity of the external quality materials was stable (80% for most of the participating laboratories. The CVs for the coagulation tests varied according to the specific instruments or reagents that were used. An educational workshop was held in November to provide hands-on experience in diagnostic hematology. During 2015, the number of participating laboratories increased, while the performance of hematology tests was similar to that observed in the previous year.

External Quality Assessment of Institutions and Instruments Using a Linear Mixed Model

BACKGROUND: External quality assessment (EQA) uses a standard deviation index (SDI), based on a peer group, to evaluate laboratory performance. However, evaluations using peer group SDIs often have limited applicability, because they are not statistically valid unless the number of institutions in the same peer group is large. The present study proposes a statistical model for simultaneously evaluating the performance of all participating institutions, as well as the performance of instruments on the market. METHODS: By assuming that proficiency test results were affected by the manufacturer, the instrument, and the institution, the effects of those factors were estimated using a linear mixed model. We used these effect estimates to calculate manufacturer, instrument, and institution SDIs. Using simulation, we evaluated the false positive rates and efficiencies of the proposed linear mixed model. RESULTS: Simulations showed that the linear mixed model empirical type I error rates preserved the nominal significance level. This model was also more statistically efficient than the peer group SDI. Rates of unacceptability were lower when using institution SDI than they were when using peer group SDI. Additional outliers that could not be evaluated using the current system were detected by the institution SDI statistic. The instrument SDI statistic detected outliers among different instrument groups. CONCLUSIONS: Institution and instrument SDIs are robust and efficient tools for EQA, and they can replace the currently used system of peer group SDI.

A Case of Pentasomy 21 With Two Isochromosome 21s in Acute Megakaryoblastic Leukemia Associated With Down Syndrome

No abstract available.

Platelet Activation Markers (beta-thromboglobulin and platelet factor 4) and Clopidogrel Drug Response in Patients with Myocardiac Infarction

BACKGROUND: Dual antiplatelet therapy (aspirin and clopidogrel) is used to prevent adverse cardiac events in patients undergoing percutaneous coronary intervention (PCI). Some patients do not respond adequately to clopidogrel. Beta-thromboglobulin (beta-TG) and platelet factor 4 (PF-4) can act as markers to detect platelet activation. We investigated the relationship between clopidogrel response and the dynamics of beta-TG and PF4 concentrations. METHODS: This study included 36 myocardial infarction (MI) patients, who underwent PCI and was indicated for dual antiplatelet therapy. Platelet reactivity, using the VerifyNow P2Y12 assay, was measured on the 3rd day of PCI. At the time of admission, and on the 3rd and 10th day of PCI, the plasma beta-TG and PF4 concentrations were quantified. RESULTS: Ten patients (27.8%) were clopidogrel non-responders displaying >208 P2Y12 reaction units. At the time of admission, levels of beta-TG in patients were elevated than that in the healthy controls (P<0.001). A similar trend was observed on the 3rd and 10th day of PCI (P<0.001). The beta-TG levels on the 10th day were reduced than those at the time of admission and on the 3rd day of PCI. PF4 levels were not different between patients and controls, and were not significantly reduced after PCI. Higher beta-TG levels were observed in clopidogrel non-responders on the 10th day, but not significant. CONCLUSIONS: Clopidogrel therapy in MI reduce beta-TG concentration, but the beta-TG and PF4 levels before and after therapy are not associated with the response to clopidogrel. Platelet-derived markers may not be suitable for distinguishing clopidogrel non-responders.

Annual Report on the External Quality Assessment Scheme for Diagnostic Hematology in Korea (2014) / 임상검사와정도관리

During 2014, the Diagnostic Hematology Subcommittee of the Korean Association of Quality Assurance for Clinical Laboratories performed laboratory proficiency testing for blood cell count, cell morphology, and coagulation tests. Four trials for blood cell count and cell morphology tests and 2 trials for coagulation tests were performed. The trials for blood cell counts had a reply rate of 96.8% among 1,343 laboratories, compared to 99.3% among 489 laboratories for cell morphology and 98.6% among 565 laboratories for coagulation tests. The homogeneity of the external quality materials was stable (80% for most of the participating laboratories. The CVs for the coagulation tests varied according to the specific instruments or reagents that were used. An educational workshop was held in July to provide hands-on experience in diagnostic hematology. During 2014, the number of participating laboratories was increased, while the performance of hematology tests was similar to that observed in the previous year.

Annual Report on External Quality Assessment in Diagnostic Hematology in Korea (2013) / 임상검사와정도관리

Diagnostic hematology subcommitee of The Korean Association of Quality Assurance for Clinical Laboratory performed laboratory proficiency testing for blood cell count, cell morphology and coagulation tests in 2013. Four trials for blood cell count and cell morphology and 2 trials for coagulation tests were executed. Average 1,308, 494, and 558 laboratories participated in the surveys of blood cell count, cell morphology and coagulation tests, respectively. The overall reply rates were 95.78%, 97.75%, and 97.38%, respectively. The homogeneity of external quality materials was stable (less than 3%) and status of use of the instrument and reagents was similar to those of the previous year. The CVs in white blood cell count, red blood cell count, platelet count, hemoglobin, and hematocrit were 3.15%, 2.00%, 5.10%, 1.81%, and 2.71%, respectively. For cell morphology, most showed concordant rate >80%. CVs of coagulation tests showed difference depending on instruments or reagent groups. An educational workshop on hands-on experience in diagnostic hematology was held in July. In 2013, the number of participating laboratories is more increased and the performance of surveys of hematology tests is similar performance compared to previous year. In addition, the revision in the way of evaluation of coagulation tests is needed.

Quantitation of T-lymphocyte Subsets Using the CELL-DYN Sapphire Automated Haematology Analyser / 임상검사와정도관리

BACKGROUND: Quantitative analysis of T-lymphocyte subsets is used to assess immune competency. Traditionally, T-lymphocyte subset analysis has been performed using flow cytometry, which requires complex instrumentation and relatively skilled manual operation. We evaluated the performance of an automated haematology analyser, the CELL-DYN Sapphire (CD Sapphire; Abbott Laboratories, USA) for T-lymphocyte subset analysis. METHODS: The precision and linearity obtained using the CD Sapphire was evaluated. T-lymphocyte subsets in blood samples from 120 patients were quantified using CD Sapphire and flow cytometry (Cytomics FC 500; Beckman-Coulter, France). The time required for complete T cell subset analysis using both methods was also evaluated. RESULTS: Results of CD Sapphire-based quantitation of CD3+, CD3+CD4+, and CD3+CD8+ cells showed intra-assay CV of less than 5% for precision and displayed linearity in the ranges of 84 to 5364, 41 to 2615, and 44 to 2800 cells/microL, respectively. There was good correlation among the CD3+, CD3+CD4+, and CD3+CD8+ cell counts as well as in the CD4/CD8 ratio (r=0.987, 0.982, 0.982, and 0.980, respectively) using CD Sapphire and flow cytometry. The mean turnaround time for the CD Sapphire (10.0+/-0.5 minutes) was significantly less than that for flow cytometry (111.8+/-8.4 minutes, P<0.001). CONCLUSIONS: T cell subset analysis using the CD Sapphire gives excellent performance and consistent results that correlate well with those obtained by flow cytometry. We conclude that this time-efficient method can replace conventional flow cytometric methods used for measuring T cell subsets.

Performance Evaluation of the Syva EMIT Methotrexate Assay on the Toshiba 200FR NEO

BACKGROUND: Methotrexate (MTX) is an antifolate antagonist that is widely used for treating various malignancies and non-malignant diseases. MTX levels should be monitored when used in high concentration to determine when to start leucovorin rescue. In this study, we evaluated the analytical performance of the EMIT Methotrexate Assay on a 200FR NEO Chemistry Analyzer (Toshiba Medical System Co., Japan) and compared it with Viva-E Drug Testing System (Siemens Healthcare, Germany). METHODS: According to the Clinical Laboratory and Standards Institute (CLSI) Evaluation Protocol (EP) 5-A2, three concentrations of the Liquichek Therapeutic Drug Monitoring Control (Bio-Rad Laboratories, USA) were analyzed twice a day for 20 days to monitor assay precision. The 200FR NEO and Viva-E instruments were compared using 40 patients' sera, according to CLSI EP9-A2. The linearity and carry-over rate were also evaluated. RESULTS: Between-run CVs for low-, medium-, and high-level controls were 4.9%, 0.9%, and 2.0%, respectively, whereas between-day CVs for low-, medium-, and high-level controls were 8.1%, 1.3%, and 3.5%, respectively. In the linearity test, the coefficient of determination (R2) was 0.98 (0.06-1.92 micromol/L). In the comparison study, R2 was 0.955, showing good correlation between the 200FR NEO and Viva-E instruments. The carry-over rate was 0.9%. CONCLUSIONS: The EMIT assay showed good precision, linearity, and carry-over rate on the Toshiba 200FR. An excellent correlation was observed when comparing results obtained using the Toshiba and Viva-E instruments. In conclusion, the Syva EMIT MTX assay can be readily used for MTX monitoring on the Toshiba 200FR NEO.

Usefulness of Procalcitonin in the Diagnosis of Early Neonatal Bacterial Infection

BACKGROUND: The use of several biochemical markers has improved the diagnosis of neonatal bacterial infection, which remains an important cause of morbidity and mortality. Recently, serum procalcitonin (PCT) has been investigated as a new marker for the detection of bacterial infection. The aim of this study was to assess the usefulness of PCT in early neonatal bacterial infection and compare the diagnostic utility of PCT with that of C-reactive protein (CRP). METHODS: We retrospectively studied 216 neonates (109 full term, 107 preterm) whose PCT was measured 24 hr after birth. Thirty-five were clinically classified into an infected group, of which 17.4% had positive cultures. Clinical data, PCT, CRP, leukocyte, and neutrophil counts were evaluated. The diagnostic performance of PCT and CRP was studied using receiver operating characteristic analysis. RESULTS: Compared to the non-infected group, the infected group displayed significantly higher median PCT (0.82 vs. 12.29 ng/mL, P<0.0001) and CRP (1.0 vs. 5.0 mg/L, P<0.0001) values, but similar leukocyte and neutrophil counts. The thresholds for PCT and CRP were 2.75 ng/mL (sensitivity, 97.1%; specificity, 76.7%) and 3.1 mg/L (sensitivity, 68.6%; specificity, 83.3%), respectively. The area under the curve for PCT was 0.937 (95% confidence interval [CI], 0.896-0.965) and 0.781 for CRP (95% CI, 0.720-0.834). CONCLUSIONS: During the first 24 hr after birth, PCT is a more sensitive marker than CRP for bacterial infection and has predictive value for early neonatal bacterial infection.

Diagnostic Utility of the URiSCAN 2 ACR Strip as a Point-of-care Test for Estimating Urine Albumin-Creatinine Ratios

BACKGROUND: Diagnosing albuminuria by measuring the urinary albumin-creatinine ratios (UACR) is important for the early detection of kidney diseases in patients with diabetes or hypertension. Currently, a few point-of-care testing (POCT) systems exist for estimating the UACR. Here, we evaluated the performance characteristics of two semi-quantitative UACR POCT assays. METHODS: Albumin and creatinine levels were quantified for 219 randomly acquired urine samples with the Toshiba TBA-200FR NEO analyzer, and the UACR were calculated. The results were compared to UACR measured using the CLINITEK Microalbumin 2 Strip (Siemens, USA) and URiSCAN 2 ACR Strip (YD diagnostics, Korea) POCT assays. RESULTS: Semi-quantitative results from the CLINITEK and URiSCAN UACR assays showed that the sensitivity and specificity of each test were, respectively, 96.7% and 62.7%, and 45.9% and 84.8%. Positive and negative predictive values of the CLINITEK and URiSCAN tests were, respectively, 50.0% and 98.0%, and 53.8% and 80.2%. The rate of agreement between URiSCAN test and CLINITEK test was 91.1% in the normal UACR range ( or =30 mg/g). CONCLUSIONS: The URiSCAN test showed higher specificity than did the CLINITEK test owing to the lower false positive results. However, the high rate of false negatives for the URiSCAN test significantly lowered its sensitivity and negative predictive values. Therefore, the sensitivity of the URiSCAN device in detecting urine albumin needs to be improved before its adoption as a reliable rule-out testing system.

A Case of Acute Promyelocytic Leukemia Concomitant with Plasma Cell Myeloma

No abstract available.

Serum Hepcidin Level as an Early Marker of Hematopoietic Activity after Allogeneic Peripheral Blood Stem Cell Transplantation / 임상검사와정도관리

BACKGROUND: Hepcidin plays a central role in the regulation of iron metabolism, and hepatic iron production is stimulated by iron load and inflammation. Recent animal studies have shown that hepcidin levels increase when hematopoiesis is blocked. We aimed to monitor pre- and post-stem cell transplantation hepcidin levels and evaluate its association with hematologic recovery. METHODS: The study group comprised 12 patients with hematologic malignancies (7 with AML, 4 with ALL, and 1 with refractory anemia with excess blasts-2) undergoing allogeneic peripheral blood stem cell transplantation (PBSCT). One day before and 3 days, 1 week, 2 weeks, 4 weeks, and 8 weeks after PBSCT, reticulocyte count and levels of Hb, ferritin, and C-reactive protein were monitored; serum hepcidin-25 was measured by ELISA. RESULTS: The median serum hepcidin-25 levels (ng/mL) were significantly higher until 1 week after PBSCT (103.6, 103.3, and 96.5) than those at 2, 4, and 8 weeks after PBSCT (63.9, 53.9, and 56.6, respectively). The reticulocyte count also significantly increased from 2 weeks after PBSCT. The hepcidin level showed an inverse correlation with reticulocyte count (r=-0.56, P or =63.9) tended to demonstrate lower Hb recovery at 8 weeks than patients with low hepcidin levels did (P=0.15), but without any differences in the incidence of complications. CONCLUSIONS: These findings indicate that hepcidin production is associated with erythropoietic activity and that hepcidin level may be used as an early marker of hematopoietic recovery in PBSCT.

The Genetic Characteristics of Multidrug-resistant Acinetobacter baumannii Coproducing 16S rRNA Methylase armA and Carbapenemase OXA-23

Acinetobacter baumannii is a gram-negative organism reported worldwide as a cause of health-care associated infections. Due to its increasing drug resistance, several studies on coproduction of armA and carbapenemase in South Korea and other parts of the world were reported, which can pose significant therapeutic threat. The aim of this study was to investigate genetic characteristics of multidrug-resistant A. baumannii coproducing armA and carbapenemase and its epidemiological relatedness. Forty-five multidrug resistant (MDR) A. baumannii clinical isolates were collected. Antimicrobial susceptibility was determined by agar dilution, Etest and VITEK 2 system. The presence of 16S rRNA methylase and carbapenemase were analyzed by polymerase chain reaction (PCR) and sequencing. Repetitive element palindromic (REP)-PCR was also performed for epidemiologic investigation. All of A. baumannii isolates harbored blaOXA-51 -like gene and 10 isolates showed an upstream ISAba1. 36 isolates (80%) showed amplification of OXA-23, all of which except one had an upstream ISAba1. 16S rRNA methylase armA was found in 44 isolates with high level resistance to aminoglycosides. The rate of coproduction was found in 36 isolates (80%). All isolates showed dominant two patterns in REP-PCR profile. The prevalence of MDR A. baumannii coproducing OXA-23 and armA was high, which the rate of blaOXA-23 coproduction was also high.

Elevated Levels of T Helper 17 Cells Are Associated with Disease Activity in Patients with Rheumatoid Arthritis

BACKGROUND: Interleukin-17 (IL-17)-producing T helper (Th) 17 cells are considered as a new subset of cells critical to the development of rheumatoid arthritis (RA). We aimed to investigate the distribution of Th1 and Th17 cells and their association with disease activity, and determine the Th17-related cytokine levels in the peripheral blood of RA patients. METHODS: Peripheral blood mononuclear cells from 55 RA and 20 osteoarthritis (OA) patients were stimulated with mitogen, and the distributions of CD4+Interferon (INF)+IL-17- (Th1 cells) and CD4+INF-IL-17+ (Th17 cells) were examined by flow cytometry. Serum levels of IL-6, IL-17, IL-21, IL-23, and tumor necrosis factor (TNF)-alpha were measured by ELISA. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were recorded. The 28-joint disease activity score (DAS28) was also assessed. RESULTS: The median percentage of Th17 cells was higher in RA patients than in OA patients (P=0.04), and in active than in inactive RA (P=0.03), whereas that of Th1 cells was similar in both groups. Similarly, the levels of IL-17, IL-21, and IL-23 were detected in a significantly higher proportion of RA patients than OA patients and the frequencies of detectable IL-6, IL-17, and IL-21 were higher in active RA than in inactive RA group. The percentage of Th17 cells positively correlated with the DAS28, ESR, and CRP levels. CONCLUSIONS: These observations suggest that Th17 cells and Th17-related cytokines play an important role in RA pathogenesis and that the level of Th17 cells in peripheral blood is associated with disease activity in RA.