Standardization of Flow Cytometric Immunophenotyping for Hematological Malignancies: The FranceFlow Group Experience

Flow cytometry is broadly used for the identification, characterization, and monitoring of hematological malignancies. However, the use of clinical flow cytometry is restricted by its lack of reproducibility across multiple centers. Since 2006, the EuroFlow consortium has been developing a standardized procedure detailing the whole process from instrument settings to data analysis. The FranceFlow group was created in 2010 with the intention to educate participating centers in France about the standardized instrument setting protocol (SOP) developed by the EuroFlow consortium and to organise several rounds of quality controls (QCs) in order to evaluate the feasibility of its application and its results. Here, we report the 5 year experience of the FranceFlow group and the results of the seven QCs of 23 instruments, involving up to 19 centers, in France and in Belgium. The FranceFlow group demonstrates that both the distribution and applicability of the SOP have been successful. Intercenter reproducibility was evaluated using both normal and pathological blood samples. Coefficients of variation (CVs) across the centers were <7% for the percentages of cell subsets and <30% for the median fluorescence intensities (MFIs) of the markers tested. Intracenter reproducibility provided similar results with CVs of <3% for the percentages of the majority of cell subsets, and CVs of <20% for the MFI values for the majority of markers. Altogether, the FranceFlow group show that the 19 participating labs might be considered as one unique laboratory with 23 identical flow cytometers able to reproduce identical results. Therefore, SOP significantly improves reproducibility of clinical flow in hematology and opens new avenues by providing a robust companion diagnostic tool for clinical trials in hematology. © 2019 International Society for Advancement of Cytometry.

Can intrapleural C-reactive protein predict VATS pleurodesis failure?

BACKGROUND

Intrapleural inflammatory reaction after surgery for spontaneous pneumothorax is a key indicator whether an effective pleurodesis has been achieved. In this study, we tested the hypothesis that intrapleural C-reactive protein (CRP) might precisely quantify the postoperative pleural inflammation, offering potentially useful information for patient management.

METHODS

The study population consisted of 75 consecutive patients who underwent video-assisted thoracoscopic pleurectomy or pleural abrasion for spontaneous pneumothorax between April 2003 and August 2004. We assessed CRP levels in pleural and blood samples taken daily in the first 4 postoperative days.

RESULTS

Intrapleural CRP profile was significantly lower in patients who underwent pleural abrasion, in younger patients (< 25 years) and in patients who were not drained before surgery. Patients with pleurodesis failure had a lower CRP peak with a delayed peak. Receiving operating characteristics (ROC) analysis showed that the cutoff value of intrapleural CRP for pleurodesis failure was 25 mg/l on the second postoperative day (sensitivity 87.5 %, specificity 66.6 %, positive predictive value 24.1, negative predictive value 97.7 %).

CONCLUSIONS

Pleural CRP levels of less than 25 mg/l on the second postoperative day indicate only a moderate pleural inflammation.

Independent prospective multicenter validation of biochemical markers (fibrotest-actitest) for the prediction of liver fibrosis and activity in patients with chronic hepatitis C: the fibropaca study

OBJECTIVES

Fibrotest (FT) and Actitest (AT) are biochemical markers of fibrosis and activity for use as a non-invasive alternative to liver biopsy in patients with chronic hepatitis C virus (HCV). The aim of this study was to perform an external validation of FT and AT and to study the discordances between FT/AT and liver biopsy in patients with chronic hepatitis C.

METHODS

A total of 519 consecutive patients with chronic HCV were prospectively included in five centers, with liver biopsy and biochemical markers taken at the same day. Fifteen patients were excluded because their biopsies could not be interpreted. Diagnostic accuracies were assessed by receiver operating characteristic (ROC) curve analysis.

RESULTS

Median biopsy size was 15 mm (range: 2-58), with 9 portal tracts (1-37) and 1 fragment (1-12). 46% (230/504) were classified F2-F4 in fibrosis and 39% A2-A3 in activity. FT area under ROC curve for diagnosis of activity (A2-A3), significant fibrosis (F2-F4), and severe fibrosis (F3-F4) were 0.73 [0.69-0.77], 0.79 [0.75-0.82], and 0.80 [0.76-0.83], respectively. Among the 92 patients (18%) with 2 fibrosis stages of discordance between FT and biopsy, the discordance was attributable to FT in 5% of cases, to biopsy in 4%, and undetermined in 9%.

CONCLUSIONS

This prospective independent and multicenter study confirms the diagnostic value of FT and AT found in the princeps study and suggests that FT and AT can be an alternative to biopsy in most patients with chronic HCV.

Accuracy of hyaluronic acid level for predicting liver fibrosis stages in patients with hepatitis C virus

BACKGROUND

In patients with chronic hepatitis C virus, liver biopsy is the gold standard for assessing liver disease stage; nevertheless, it is prone to complications, some of them serious. Non-invasive methods have been proposed as surrogate markers for liver fibrosis. It was shown that serum hyaluronic acid (HA) level increases with the development for liver fibrosis. The aim of this study was to evaluate the diagnostic value of HA as well as to determine the HA level cut-off for predicting the presence or absence of fibrosis, severe fibrosis, and cirrhosis.

RESULTS

405 patients with chronic hepatitis C were prospectively included with biomarker measurement and liver biopsy done the same day: 151 in the training set (only biopsy lengths of 25 mm or more) and 254 in the validation set. For the discrimination of significant fibrosis, severe fibrosis, and cirrhosis in the training set, the areas under curve (AUCs) were 0.75 +/- 0.03, 0.82 +/- 0.02, and 0.89 +/- 0.03, respectively. Absence of significant fibrosis, severe fibrosis, and cirrhosis can be predicted by HA levels of 16, 25, and 50 microg/l, respectively (with negative predictive values of 82%, 89%, and 100%, in the same order). Presence of significant fibrosis, severe fibrosis, and cirrhosis can be predicted by HA levels of 121, 160, and 237 microg/l, respectively (with positive predictive values of 94%, 100%, and 57%, in the same order).

CONCLUSION

In the validation set, HA was accurate in predicting significant fibrosis, severe fibrosis, and cirrhosis with AUCs of 0.73, 0.77, and 0.97, respectively. Moreover, accurate HA level cut-offs were defined for predicting significant fibrosis, severe fibrosis, and cirrhosis. Thus, the study supports that HA level may be clinically useful as a non-invasive marker for liver fibrosis and/or cirrhosis.

CD48 may serve as an accessory molecule for the activation of a subset of human gamma/delta T cells

To further assess the role of CD48 in the interaction of human gamma/delta T cells with their specific target, we generated two series of alloreactive clones, L and K. These clones express a V1-D-J1-C delta chain associated to V3-J2-C2 (L) or V2-J2-C2 (K) gamma chain. Functionally they were CTLs able to lyse the sensitizing B-cell line E418. The cytotoxicity of the L and K clones toward E418 was inhibited by anti-CD48 mAb. That of the L clones was also inhibited by anti-HLA class I mAbs. Variation in L and K lysis profile was observed against a panel of CD48+ targets, further strengthening the argument that they display distinct specificities and suggesting that they do not recognize CD48. Heterogeneity in TCR gene segment usage, MHC-dependent recognition of E418 by the L clones, and resistance of some CD48+ targets strongly suggest that CD48 itself does not interact with L and K TCR. Transfection of CHO cells with CD48 induced killing by the K clones. This killing was inhibited by anti-CD48 mAbs. Taking into account the recent reports on CD48 as an accessory molecule, our results suggest that by binding to CD2 (and/or an unknown ligand), CD48 may serve to strengthen E/T interaction and may contribute to the activation of a minor subset of gamma/delta T cells.