Impact of blood storage and sample handling on quality of high dimensional flow cytometric data in multicenter clinical research.

Obtaining reliable and reproducible high quality data in multicenter clinical research settings requires design of optimal standard operating procedures. While the need for standardization in sample processing and data analysis is well-recognized, the impact of sample handling in the pre-analytical phase remains underestimated. We evaluated the impact of sample storage time (≈transport time) and temperature, type of anticoagulant, and limited blood volume on reproducibility of flow cytometric studies. EDTA and Na-Heparin samples processed with the EuroFlow bulk lysis protocol, stained and stored at 4 °C showed fairly stable expression of cell surface markers and distribution of the major leukocyte populations for up to 72 h. Additional sample fixation (1% PFA, Fix & Perm) did not have any beneficial effects. Blood samples stored for <24 h at room temperature before processing and staining seemed suitable for reliable immunophenotyping, although losses in absolute cell numbers were observed. The major losses were observed in myeloid cells and monocytes, while lymphocytes seemed less affected. Expression of cell surface markers and population distribution were more stable in Na-Heparin blood than in EDTA blood. However, storage of Na-Heparin samples was associated with faster decrease in leukocyte counts over time. Whole blood fixation strategies (Cyto-Chex, TransFix) improved long-term population distribution, but were detrimental for expression of cellular markers. The main conclusions from this study on healthy donor blood samples were successfully confirmed in EDTA clinical (patient) blood samples with different time delays until processing. Finally, we recognized the need for adjustments in bulk lysis in case of insufficient blood volumes. Despite clear overall conclusions, individual markers and cell populations had different preferred conditions. Therefore, specific guidelines for sample handling should always be adjusted to the clinical application and the main target leukocyte population.

Propylthiouracil induced ANCA-associated vasculitis in a 14-year-old girl.

BACKGROUND: Antineutrophil cytoplasmic antibodies (ANCAs) are the serologic hallmark of ANCA-associated primary small-vessel vasculitides (AAVs), but these antibodies have also been described in other autoimmune diseases such as inflammatory bowel diseases. Furthermore, different drugs are linked to the induction of ANCA, including propylthiouracil (PTU). However progression into clinical overt vasculitis is less common. CASE-DIAGNOSIS/TREATMENT: We describe the case of a young girl with Graves' disease presenting with fatigue, fever, episcleritis and arthritis. The unexpected double myeloperoxidase/proteinase 3-ANCA positivity triggered a multidisciplinary diagnostic work-up and resulted in the diagnosis of a clinically overt PTU-induced AAV. After PTU-withdrawal and treatment with high-dose corticosteroids, a favorable clinical and biochemical evolution was obtained. CONCLUSIONS: The use of PTU in the management of hyperthyroidism is not considered first-line treatment in Europe and is even less commonly used in children. Nevertheless, pediatricians should be aware of the possibility of PTU-induced AAV, especially in the presence of multiple ANCA reactivities. Therefore, the use of this drug should be weighed carefully in children.

Optimization and diagnostic performance of a single multiparameter lineblot in the serological workup of systemic sclerosis.

INTRODUCTION: Detection of systemic sclerosis-associated antibodies (SSc-Ab) in routine clinical practice is mostly restricted to anti-centromere and anti-topoisomerase-I antibodies. However, also other SSc-Ab (e.g. anti-RNA-polymerase-III, anti-PM/Scl, anti-fibrillarin and anti-Th/To) have been shown to be valuable diagnostic and prognostic markers for the disease, but testing methodologies for their detection are laborious and time-consuming. This study aimed to optimize interpretational criteria of a multiparameter lineblot (LB) for the parallel detection of SSc-Ab. We also assessed its global diagnostic value as an alternative for combined conventional techniques (CCT) in the serological workup of systemic sclerosis (SSc) patients. METHODS: The presence of SSc-Ab (anti-centromere, anti-topoisomerase-I, anti-RNA-polymerase-III, anti-PM/Scl, anti-fibrillarin and anti-Th/To) was identified by LB on 145 consecutive SSc patients and on 277 disease controls. Diagnostic sensitivity and specificity were calculated for both individual reactivities and the global LB. Cohen's kappa coefficient was used to examine agreement between LB and CCT and guided the definition of final interpretational criteria for LB. RESULTS: Applying the optimal cut-off values and interpretational criteria, LB identified SSc-Ab in 110 SSc patients (sensitivity=76%) and in 19 disease controls (specificity=93%). Globally, there was a substantial agreement between CCT and LB (κ=0.787, concordance 92.4%). LB and CCT showed a very good correlation (κ>0.800) for most SSc-Ab (anti-centromere, anti-topoisomerase-I, anti-RNA-polymerase-III and anti-PM/Scl). The best agreement for anti-RNA-polymerase-III and anti-PM/Scl was achieved when positivity for both components was taken as a criterion. CONCLUSIONS: LB is a reliable alternative for the laborious and time-consuming conventional techniques in the diagnostic workup of SSc, especially for the detection of anti-centromere, anti-topoisomerase-I, anti-RNA-polymerase-III and anti-PM/Scl.

Validation of a new screening strategy for anti-extractable nuclear antigen antibodies.

OBJECTIVE: Although indirect immunofluorescence (IIF) is the most widely applied screening test for antinuclear antibodies (ANA), it lacks specificity for the identification of specific diseases or antigen reactivities. The aim of the present study was to validate an anti-extractable nuclear antigen (ENA) screening strategy encompassing a three-step cascade whereby an ELISA with pooled specific ENA is positioned between the IIF and the final anti-ENA identification. METHODS: Sera from 4 populations were tested for anti-ENA using an automated ELISA (EliA Symphony) and a line immunoassay (INNO-LIA ANA update). RESULTS: At the manufacturer's cut-off, a 96% sensitivity (95% CI 94%-98%) and 96% specificity (95% CI 94%-98%) of EliA Symphony for anti-ENA was obtained in a consecutive selection of 328 IIF positive serum samples referred for ANA testing. In addition, a high sensitivity was demonstrated for anti-ENA reactivities in patients with SLE (99%, 95% CI 97%-101%) and SSc (100%), and for anti-ENA monoreactivities. CONCLUSION: The EliA Symphony test was shown to be a sensitive second-line screening test for anti-ENA antibodies. In the context of a high clinical suspicion of connective tissue disease or autoreactivities not included in the EliA Symphony assay, third-line testing may be useful, even if the anti-ENA screening is negative.

Use of a multiplex real-time PCR to study the incidence of human metapneumovirus and human respiratory syncytial virus infections during two winter seasons in a Belgian paediatric hospital.

Viruses are an important cause of acute respiratory tract infection (ARTI) in children. This study aimed to develop and evaluate a rapid molecular diagnostic test (duplex real-time PCR) for human respiratory syncytial virus (hRSV) and human metapneumovirus (hMPV), and to determine the frequency of these two viruses as causative agents of ARTI in Belgium. Nasopharyngeal aspirates were collected over two winter and spring seasons (November 2003 to May 2004 and November 2004 to May 2005) from children aged <5 years with ARTI (n = 778). The duplex real-time PCR showed a linear range of 10(4)-10(10) copies/mL for both hMPV and hRSV. Analysis of the stability of the hRSV and hMPV genomes revealed that nasopharyngeal aspirates could be stored at room temperature for up to 1 month without significant loss of detection. hRSV was detected by antigen testing and by real-time PCR; hMPV was detected by real-time PCR only. The hRSV antigen test was less sensitive than PCR, and failed to detect one-third of the hRSV infections. Overall, 54 (6.9%) and 306 (39.3%) of the 778 samples were positive for hMPV and hRSV, respectively. Both viruses infected young infants, but the mean age of infants infected by hRSV was lower than that of infants infected by hMPV (12 months vs. 17 months, respectively).