Establishment of a healthy human range for the whole blood "OX40" assay for the detection of antigen-specific CD4+ T cells by flow cytometry.

BACKGROUND: Clinical investigation of antigen-specific T cells in potentially immunodeficient patients is an important and often challenging aspect of patient diagnostic work up. Methods for detection of microbial exposure to the T-cell compartment exist but are laborious and time consuming. Recently, a whole blood technique involving flow cytometry and detection of CD25 and OX40 (CD134) expression on the surface of activated CD4+ T cells was shown to be accurate and concordant when compared with more traditional methods of antigen-specific T-cell detection. METHODS: Whole heparinized blood was collected from healthy donors and set up using the "OX40" assay to detect antigen-specific CD4+ T-cell responses to Varicella Zoster Virus, Epstein-Barr Virus (EBV), Cytomegalovirus, Candida albicans, and Streptococcus pneumoniae. RESULTS: The "OX40" assay technique was clinically validated for routine use in an NHS clinical immunology laboratory by analysis of incubation length (40-50 h), sample transport time (up to 24 h at room temperature), concordance with serology testing, proliferation and interferon-gamma production. In addition, 63 healthy controls (age range 21-78) were tested for responses to generate a healthy control reference range. CONCLUSIONS: The OX40 assay, as presented in this report, represents an economical, rapid, robust whole blood technique to detect antigen-specific T cells, which is suitable for clinical immunology diagnostic laboratory use.

Establishment of a healthy human range for the whole blood 'OX40' assay for the detection of antigen-specific CD4+ T cells by flow cytometry.

Background: Clinical investigation of antigen-specific T cells in potentially immunodeficient patients is an important and often challenging aspect of patient diagnostic work up. Methods for detection of microbial exposure to the T cell compartment exist but are laborious and time consuming. Recently, a whole blood technique involving flow cytometry and detection of CD25 and OX40 (CD134) expression on the surface of activated CD4+ T cells was shown to be accurate and concordant when compared with more traditional methods of antigen-specific T cell detection. Methods: Whole heparinised blood was collected from healthy donors and set up using the 'OX40' assay to detect antigen specific CD4+ T cell responses to Varicella Zoster Virus (VZV), Epstein-Barr Virus (EBV), Cytomegalovirus (CMV), Candida albicans and Streptococcus pneumoniae. Results: The 'OX40' assay technique was clinically validated for routine use in an NHS clinical immunology laboratory by analysis of incubation length (40-50 hours), sample transport time (up to 24 hours at room temperature), concordance with serology testing, proliferation and IFN-γ production. In addition, 63 healthy controls (age range 21-78) were tested for responses to generate a healthy control reference range. Conclusions: The OX40 assay, as presented in this report, represents an economical, rapid, robust whole blood technique to detect antigen-specific T cells which is suitable for clinical immunology diagnostic laboratory use. © 2013 Clinical Cytometry Society.

The diagnostic significance of serum IgG4 levels in patients with autoimmune pancreatitis: a UK study.

BACKGROUND: Autoimmune pancreatitis (AIP) is recognised as an end organ manifestation of the systemic condition known as IgG4-sclerosing disease. One major characteristic of this disease, regardless of its location in the body, is the presence of high levels of circulating serum IgG, in particular IgG4 antibody. In the case of AIP, differential diagnosis from other conditions of the pancreas and biliary system, particularly cancers, can be difficult, but could result in avoiding invasive procedures and surgery. Earlier studies have evaluated the use of checking IgG4 levels in AIP diagnosis; these have produced variable results. OBJECTIVE: To further assess the diagnostic significance of serum IgG4 levels in AIP and investigate its value in differentiating from cancer of the gastroenterological system. METHODS: A retrospective study of 196 IgG4-requested samples from a 24-month period was examined. Samples were sorted into confirmed AIP, cancer or other pancreatic conditions including primary sclerosing cholangitis. RESULTS: Patients with AIP possessed a mean serum IgG level that was significantly higher compared with all other groups (mean serum IgG level=19.0 g/l+/-2.5, P<0.001). The mean serum IgG4 level of AIP patients was also significantly higher compared with all other conditions including cancer patients (mean IgG4 level=3.7 g/l+/-0.5, P<0.001). CONCLUSION: This data lends support to circulating IgG4 levels only being used as an accompanying diagnostic marker to imaging, histology and clinical presentation. In particular, this may help in differentiating between AIP and pancreatic carcinoma.

Clinical impact and reliability of pleural fluid mesothelin in undiagnosed pleural effusions.

RATIONALE: Serum mesothelin is a new biomarker for the diagnosis of mesothelioma. Patients with mesothelioma commonly present with pleural effusions. To define the clinical utility of mesothelin quantification in pleural fluid, we assessed its additional value over pleural fluid cytology and its short-term reproducibility and reliability after pleural inflammatory processes, including pleurodesis. OBJECTIVES: To assess the diagnostic role of pleural fluid mesothelin and the effect of common clinical factors that may influence measurement accuracy. METHODS: Mesothelin was quantified in 424 pleural fluid and 64 serum samples by ELISA. Fluid was collected prospectively from 167 patients who presented with pleural effusions for investigation. Serial pleural fluid samples were obtained from patients (n = 33) requiring repeated drainage. Mesothelin levels were also measured in patients (n = 32) prepleurodesis and postpleurodesis. MEASUREMENTS AND MAIN RESULTS: Pleural fluid mesothelin concentrations were significantly higher in patients with mesothelioma (n = 24) relative to those with metastatic carcinomas (n = 67) and benign effusions (n = 75): median (interquartile range, 25th-75th percentile) = 40.3 (18.3-68.1) versus 6.1 (1.5-13.2) versus 3.7 (0.0-12.4) nM, respectively, P < 0.0001. Mesothelin measurement was superior to cytological examination in the diagnosis and exclusion of mesothelioma (sensitivity, 71 vs. 35%; specificity, 89 vs. 100%; negative predictive value, 95 vs. 82%, respectively). In patients with "suspicious" cytology, pleural fluid mesothelin was 100% specific for mesothelioma, and in cytology-negative effusions (n = 105) offered a negative predictive value of 94%. Intraindividual reproducibility of pleural fluid mesothelin was excellent: mean (+/-SD) variation, -0.15 (+/-8.41) nM in samples collected within 7 days from patients with mesothelioma. Measurements remained reliable after pleurodesis and were not affected by the presence of bacteria. CONCLUSIONS: Pleural fluid mesothelin provides additional diagnostic value relative to cytological examination. Mesothelin measurements are reproducible and not affected by inflammatory pleural processes.