Multicentric evaluation of the variability of digital morphology performances also respect to the reference methods by optical microscopy

INTRODUCTION

Despite the important diagnostic role of peripheral blood morphology, cell classification is subjective. Automated image-processing systems (AIS) provide more accurate and objective morphological evaluation. The aims of this multicenter study were the evaluation of the intra and inter-laboratory variation between different AIS in cell pre-classification and after reclassification, compared with manual optical microscopy, the reference method.

METHODS

Six peripheral blood samples were included in this study, for each sample, 70 May-Grunwald and Giemsa stained PB smears were prepared from each specimen and 10 slides were delivered to the seven laboratories involved. Smears were processed by both optical microscopy (OM) and AIS. In addition, the assessment times of both methods were recorded.

RESULTS

Within-laboratory Reproducibility ranged between 4.76% and 153.78%; between-laboratory Precision ranged between 2.10% and 82.2%, while Total Imprecision ranged between 5.21% and 20.60%. The relative Bland Altman bias ranged between -0.01% and 20.60%. The mean of assessment times were 326 ± 110 s and 191 ± 68 s for AIS post reclassification and OM, respectively.

CONCLUSIONS

AIS can be helpful when the number of cell counted are low and can give advantages in terms of efficiency, objectivity and time saving in the morphological analysis of blood cells. They can also help in the interpretation of some morphological features and can serve as learning and investigation tools.

Within- and between-laboratory reproducibility and predictive capacity of amino acid derivative reactivity assay (ADRA) using a 0.5 mg/mL test chemical solution: Results of the study for reproducibility confirmation implemented in five participating laboratories

The amino acid derivative reactivity assay (ADRA) is an in chemico alternative assay for skin sensitization listed in OECD test guideline 442C. ADRA evaluates the reactivity of sensitizers to proteins, which is key event 1 in the skin sensitization adverse outcome pathway. Although the current key event 1 evaluation method is a simple assay that evaluates nucleophile and test chemical reactivity, mixtures of unknown molecular weights cannot be evaluated because a constant molar ratio between the nucleophile and test chemical is necessary. In addition, because the nucleophile is quantified by HPLC, the frequency of co-eluting the test chemical and nucleophile increases when measuring multi-component mixtures. To solve these issues, test conditions have been developed using a 0.5 mg/mL test chemical solution and fluorescence-based detection. Since the practicality of these methods has not been substantiated, a validation test to confirm reproducibility was conducted in this study. The 10 proficiency substances listed in the ADRA guidelines were tested three times at five different laboratories. The results of both within- and between-laboratory reproducibility were 100%, and the results of ultraviolet- and fluorescence-based measurements were also consistent. In addition to the proficiency substances, a new positive control, squaric acid diethyl ester, was tested three times at the five laboratories. The results showed high reproducibility with N-(2-(1-naphthyl)acetyl)-l-cysteine depletion of 37%-52% and α-N-(2-(1-naphthyl)acetyl)-l-lysine depletion of 99%-100%. Thus, high reproducibility was confirmed in both evaluations of the 0.5 mg/mL test chemical and the fluorescence-based measurements, validating the practicability of these methods.