Pru p 3-specific IgE affinity is crucial in severe peach-allergy patients.

Background: Peach allergy is common food allergen. Allergen components-specific antibodies of different isotypes in peach-allergy patients are poorly studied. Factors other than Pru p 3-sIgE levels may be related to severe symptoms. Objective: To evaluated peach component-specific-IgE, IgG1, and IgG4 characteristics in individuals with and without peach allergy, and Pru p 3-sIgE affinity in patients with different clinical symptoms. Methods: Fifteen healthy controls and 32 peach-allergy patients were enrolled. sIgE, sIgG1, and sIgG4 to 5 Escherichia coli-expressed peach-allergen components were determined by enzyme-linked immunosorbent assays. Pru p 3-sIgE affinity was measured in Pru p 3-sIgE-positive patients, using immunoadsorbance. Results: Patients were divided into oral allergy syndrome (OAS) and peach-induced anaphylaxis (PIA) groups. Serum Pru p 1-, Pru p 2-, Pru p 3-, Pru p 4-, and Pru p 7-sIgG1s were detected. Pru p 1- and Pru p 2-sIgG1 levels were higher in healthy controls, but Pru p 3-sIgG1 levels were significantly higher in peach-allergy patients. Pru p 1-, Pru p 3-, and Pru p 4-sIgG4-positivity was significantly greater among patients than among controls. Pru p 3 was the predominant allergen in peach-allergy patients. Allergen-sIgG1 and sIgG4 were similar between OAS and PIA patients. Pru p 3-sIgE levels were significantly higher in PIA patients, but Pru p 3-sIgE-positivity was similar in both groups. In Pru p 3-sIgE-positive patients, Pru p 3-sIgE affinity was significantly higher in PIA than OAS patients. Conclusions: Allergen-sIgG1 was associated with allergen exposure. Both Pru p 3-sIgE levels and affinity are key factors in severe peach-allergy patients.

Comparison of four different immunoassays and a rapid isotope-dilution liquid chromatography-tandem mass spectrometry assay for serum folate.

OBJECTIVES: Accurate measurement of serum folate is essential for the diagnosis and management of various disorders. This study aims to investigate the between-method differences of four immunoassays and a rapid isotope-dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) method. METHODS: Roche Cobas (USA), Abbott Alinity i2000 (USA), Beckman Coulter Access (USA), Mindray CL-6000i (China), and the ID-LC-MS/MS method were compared using 46 human serum samples. The results were analysed by Passing-Bablok regressions and Bland-Altman plots. A bias of 13.31% based on biological variation was used as the bias criterion. RESULTS: All the within-run and total coefficients of variation (CVs) met the specification. The folate concentrations determined by all the assays were significantly different (p=0.0028). All assays had correlation coefficients over 0.97 with each other. The 95% confidence intervals (CIs) for the slope seldom contained 1 and few 95% CIs for the intercept contained 0 in the regression equations. Compared to ID-LC-MS/MS, the biases of all assays ranged from -20.91 to 13.56 nmol/L, and the mean relative biases ranged from -9.85 to 40.33%. The predicted mean relative biases at the medical decision levels rarely met the criterion. CONCLUSIONS: Assays for serum folate had good correlations with each other but lacked good agreement. The accuracy and consistency of assays for serum folate should be measured and assessed routinely. Standardization work to improve the accuracy of serum folate assays, such as the extension of traceability to reference methods or materials, calibration standardization efforts, and assay-adjusted cut-offs should be promoted.

Commutability of possible external quality assessment materials for progesterone measurement.

BACKGROUND: The commutability of control materials used for external quality assessment (EQA) programs is of great importance. Evaluating the commutability of control materials is crucial to assess their suitability for EQA programs. METHODS: Forty-eight individual patient serum samples, commercial EQA samples, human serum pools (HSPs), commercially available sterile filtered charcoal stripped serum (CS) and swine serum were analyzed using the isotope dilution liquid chromatography-tandem mass spectrometry (ID LC-MS/MS) comparative method and six immunoassays for progesterone. The commutability was assessed according to the EP14-A2 guideline and the difference in bias approach, respectively. RESULTS: According to the EP14-A2 guideline, HSPs and CS were commutable for all the tested immunoassays, while swine serum showed positive matrix effects in some assays. Based on the difference in bias approach, a large number of inconclusive and noncommutable results appeared. CONCLUSIONS: The commutability of the processed materials varied depending on which evaluation approach and criterion was applied. Noncommutability of the EQA materials was observed. And HSPs and CS were possible commutable candidate control materials according to the EP14-A2 guideline.

Commutability of reference materials for alkaline phosphatase measurements.

Commutability is a prerequisite when using a candidate reference materials (CanRMs) for calibration and trueness control of routine methods or for value transfer from the reference method to end-user calibrators of routine methods through a calibration hierarchy. The CanRMs include commercial general chemistry materials (GCs), enzyme trueness verification materials (ETVs), and secondary reference materials (SRMs). The commutability of CanRMs was evaluated based on the difference in bias and EP14-A3 to investigate their suitability for ALP measurement. A total of 44 fresh individual clinical samples (CSs) and the CanRMs were analyzed by six routine methods (validated methods) and by IFCC primary reference method (comparative method) for the determination of Alkaline Phosphatase (ALP). The commutability was performed based on IFCC working group recommendations for assessing commutability and analyzed according to EP14-A3 guide and difference in bias approach, respectively. The bias of the routine methods was assessed according to CLSI guidelines. The result of commutable materials obtained from the two evaluation approaches are not significantly different. It was observed that the routine methods with lower bias were associated with more commutable CanRMs. None of the CanRMs were suitable for use as commutable RMs. The findings of this study have a number of important implications for future practice.