Impact of anti-squamous cell carcinoma antigen antibodies on serum squamous cell carcinoma antigen levels measured by chemiluminescent immunoassay and chemiluminescent enzyme immunoassay.

OBJECTIVE: The serum squamous cell carcinoma antigen (SCCA) level is a well-known tumor marker for squamous cell carcinoma. In this study, we examined the impact of immunoglobulin (Ig)-bound macromolecular SCCA on serum SCCA levels measured by 2 different methods. METHODS: Seventy-five serum samples with an SCCA level >5.0 ng/mL as determined by a chemiluminescent immunoassay (CLIA) were also analyzed using a chemiluminescent enzyme immunoassay (CLEIA). The levels of IgG- and IgA-type anti-SCCA antibodies, which form immunoglobulins and macromolecules, respectively, were determined using an enzyme-linked immunosorbent assay. An absorption test was performed to confirm the presence of anti-SCCA antibodies. RESULTS: The correlation coefficient between the values measured by CLEIA and CLIA was 0.768. The ratio of SCCA levels measured by CLEIA to those measured by CLIA in 14 samples with IgG-type anti-SCCA antibodies was significantly lower than that in samples without these antibodies (P < .031). Absorption tests showed that SCCA levels measured by CLIA might be falsely high in samples with IgG-type anti-SCCA antibodies, probably due to reactions with SCCA1. CONCLUSION: The level of SCCA as measured by CLIA and CLEIA methods correlate well, but the presence of SCCA antibodies can affect the results of the CLIA method.

Instability of harmonized thyroid-stimulating hormone immunoassays in clinical practice.

OBJECTIVE: Thyroid-stimulating hormone (TSH) harmonization is effective in minimizing differences between the results of immunoassays in healthy subjects. However, the effectiveness of TSH harmonization in clinical practice has not been investigated. The aim of this study was to evaluate the instability of TSH harmonization in clinical practice. METHODS: We compared the reactivities of four harmonized TSH immunoassays using combined difference plots of 431 patients. We selected patients with statistically significant deviations in TSH levels and analyzed their thyroid hormone levels and clinical characteristics. RESULTS: The combined difference plots showed that one harmonized TSH immunoassay exhibited markedly different reactivity even after TSH harmonization compared with the other three immunoassays. Among 109 patients with mild-to-moderate elevation of TSH levels, we selected 15 patients with statistically significant deviations in TSH levels according to the difference plots of three harmonized TSH immunoassays, excluding one immunoassay that showed different reactivity. The thyroid hormone levels of three patients were misclassified as hypothyroidism or normal due to deviating TSH levels. In terms of clinical characteristics, these patients were in poor nutritional status and general condition, possibly due to their severe illness (e.g., advanced metastatic cancer). CONCLUSION: We have confirmed that TSH harmonization in clinical practice is relatively stable. However, some patients showed deviating TSH levels in the harmonized TSH immunoassays, indicating the need for caution, particularly in poorly nourished patients. This finding suggests the presence of factors that contribute to the instability of TSH harmonization in such cases. Further investigation is warranted to validate these results.

[Evaluation of a Fully Automated Analyzer for Antinuclear Antibody Test Using Indirect Immunofluorescence Assay].

The fully automated HELIOS® system for antinuclear antibody (ANA) test is capable of automatically per- forming all IFA procedures. We evaluated the analytical performance, characteristics and utility of HELIOS system as ANA screening test. We compared HELIOS system and the conventional methods in sera from 161 connective tissue disease (CTD) patients and 250 healthy individuals. The presence and titer of ANA were automatically determined by performing HELIOS system at 1:80 dilution and the ANA titers were com- pensated by several dilution and visual determination in sera with a high ANA titer and ANA-positive sera combined with anti-cytoplasmic antibody. The ANA staining patterns were assessed by visual determination of the digital image on HELIOS system. The total concordance rate between the conventional method and HELIOS system was 94.4%. The concordance of ANA titer (within ± 1 tube difference) between the con- ventional method and automated or compensated evaluation of HELIOS system was 85.7% or 98.8%, respec- tively. The concordance rate of six nuclear staining patterns was from 81.4% to 100% and the discrepancies of granular staining pattern might be caused by the fixation of HEp-2 cells. The positive rates of ANA in CTD patients and healthy individuals were comparable with the conventional methods. Taken together, HELIOS system can appropriately perform the automated determination of ANA except in some cases and is useful as ANA screening test. Furthermore, this system can contribute not only an efficient IFA procedure but also the ANA standardization by IFA. [Original].

[Performance Utility of High Sensitivity Quantitative Assay for HBs Antigen].

A high sensitivity quantitative assay for hepatitis B virus (HBV) surface antigen (HBsAg-HQ assay) was recently developed and is useful for earlier detection of HBV reactivation. We created HBsAg-HQ assay operational proce- dures by the sample transport system and laboratory information system. In this study, we evaluated the perfor- mance and utility of the HBsAg-HQ assay based on our operational procedures using internal quality control (IQC) data and 13,762 samples routinely measured for 8 months. The IQC data of the HBsAg-HQ assay demonstrated good accuracy (CV: 1.6-2.7%). The difference in IQC data between two of the same analyzers or several reagent lots had no clinical significance. Of 13,762 samples, HBsAg titer was negative in 12,592(91.5%) and positive in 1,169(8.5%), and HBsAg negative samples were remarkably lower(<0.001 IU/mL) than the cut-off value(0.005 IU/mL). Among 114 HBsAg weakly positive samples ranging from 0.005 to 1.000 IU/mL, false positive results occurred in 12 samples, which were converted into negative results after re-measurement. We could effectively perform carry-over prevention and dilution of high titer samples using our operational procedures. Furthermore, we performed inhibition test in 52 HBsAg weakly positive samples, and 20 samples, most of which were taken from patients with connective tissue disease or malignancy, were judged as non-specific reactivity. Taken together, our operational HBsAg-HQ assay procedures may contribute to efficient workflow for routine testing. Moreover, the HBsAg-HQ assay may be clinically useful for not only highly sensitive assays, but also for reducing false positives.

[Evaluation of a Computer-Aided Microscope System and Its Anti-Nuclear Antibody Test Kit for Indirect Immunofluorescence Assay].

Antinuclear antibody (ANA) testing is indispensable for diagnosing and understanding clinical conditions of autoimmune diseases. The indirect immunofluorescence assay (IFA) is the gold standard for ANA screening, and it can detect more than 100 different antibodies, such as anti-PCNA as well as anti-cytoplasmic antibodies. However, complicated procedures of conventional IFA and visual interpretation require highly skilled laboratory staff. This study evaluates the capability, characteristics, and applicability of the recently developed ANA detection system (EUROPattern Cosmic IFA System, EPA) using HEp20-10 cells and the automated pattern recognition microscope. Findings using EPA and conventional methods were compared in 282 sera obtained from connective tissue disease patients and 250 sera from healthy individuals. The concordance of the positivity rate, antibody titer (within +/- 1 tube difference), and the accurate recognition rate of ANA patterns between the automated EPA method and the microscopic judgement of the EPA image by eye was 98.9, 97.4, and 55.3%, respectively. The EPA method showed concordance of the positivity rate as high as 93.3% and concordance of the antibody titer as high as 94.0% (within +/- 1 titer) compared with the conventional method. Regarding the four typical patterns of ANA (homogeneous, speckled, nucleolar, and centromere), large differences between the EPA and conventional methods were not observed, and the rate of concordance between the final EPA result and the conventional method was from 94.1 to 100%. The positivity rate of ANA using the EPA and conventional methods showed marked agreement among the six connective tissue diseases (SLE, MCTD, SSc, PM/DM, and SS) and healthy individuals. Although the EPA system is not considered a complete system and laboratory staff should verify the results, it is a useful system for routine ANA analysis because it contributes to ANA standardization and an efficient workflow.

Plasma platelet-derived microparticles in patients with connective tissue diseases.

OBJECTIVE: To clarify the role of platelet-derived microparticles (PDMP), which are small vesicles with thrombotic and immunological properties, in systemic lupus erythematosus (SLE), systemic sclerosis (SSc), dermatomyositis/polymyositis (PM/DM), and mixed connective tissue disease (MCTD). METHODS: Plasma levels of PDMP were measured by ELISA, and compared among patients with one of the 4 diseases. Association of PDMP levels with clinical characteristics and medication of the patients was also examined. RESULTS: PDMP levels were higher in patients with MCTD and SSc than in controls. Multiple linear regression analysis revealed that patients with Raynaud's phenomenon (RP) showed higher PDMP levels than those without. PDMP levels in individual patients did not fluctuate significantly over several months. CONCLUSION: PDMP level is associated with MCTD, SSc, and RP, and could be a novel marker for RP.

[Acute myeloid leukemia with t(16;21)(q24;q22) in a child].

The t(16;21)(q24;q22), a rare chromosomal translocation observed mostly in therapy-related acute myelogenous leukemia (AML), produces a RUNX1-CBFA2T3 fusion gene. Here we report a de novo AML case of 1-year-old girl with t(16;21)(q24;q22). In this case, we demonstrated the RUNX1-CBFA2T3 fusion gene and established quantitative RT-PCR for detecting minimal residual disease.

[Usefulness of the formula for predicting creatinine clearance from serum cystatin C].

Estimation of Glomerular filtration rate (GFR) is crucial for the detection of renal insufficiency. In clinical practice, GFR is generally estimated from Ccr by some prediction formulas including the serum creatinine concentration and some variables: age, sex, body size. It has been suggested that serum cystatin C is less influenced by sex, body size, muscular mass or inflammation. In several studies, serum cystatin C performed better than serum creatinine did as a marker to detect GFR reduction. We developed the formula for predicting creatinine clearance (Ccr) from serum cystatin C, serum creatinine and serum beta 2-microgroburin by multiple regression analysis. In this study, we analysed 24-hour Ccr and variables (sex, age and BMI) in 82 subjects with renal diseases to develop suitable formulas. Our serum cystatin C formula is as follows: Ccr (ml/min/1.73m2) = (12.14-0.03 x age-1.72 x serum cystatin C) 2. Correlation between measured 24-hour Ccr and predicted Ccr by our serum cystatin C formula was higher (r=0.852) than our serum creatinine formula (r=0.755), serum beta 2-microgroburin formula (r=0.793), Cockcroft-Gault formula (r=0.836) and Horio formula (r=0.825). Accuracy within 15% was higher (39.0%) than other formulas (25.6-30.5%). Our formula using serum cystatin C for predicting Ccr is a useful and precise marker for Ccr than other commonly used formulas using serum creatinine.

[Usefulness of serum cystatin C for the diagnosis of impaired renal function].

Creatinine clearance (Ccr) is generally used as a halmark of glomerular filtration rate (GFR) in clinical medicine. Recently, it has been suggested that serum cystatin C measurement in serum reflects GFR. We compared serum cystatin C, serum creatinine, and serum beta2-microgrobrin in 70 patients with renal diseases in reference to creatinine clearance. The correlation between Ccr and 1/cystatin C was higher (r = 0.830) than that between Ccr and 1/serum creatinine (r = 0.789) or 1/serum beta2-microgroburin (r = 0.732). The levels of serum cystatin C in patients with Ccr ranging from 51 to 70 ml/min were significantly higher than those in patients with Ccr ranging more than 91 ml/min. Receiver-operated characteristic (ROC) analysis revealed that serum cystatin C showed the highest area under the curve among the three when Ccr = 90 ml/min was used as the cutoff point. We conclude that serum cystatin C is more useful than serum creatinine to detect early renal dysfunction.