Comparison among different measurement systems for fibrinogen using fresh samples and frozen samples

Comparability evaluation of serum and plasma cytokine levels by multiplex bead-based flow cytometry

BACKGROUND AND AIMS

Serum and plasma are the most common matrices for cytokine assays. Nevertheless, there is a lack of comparability evaluation for cytokine levels in two matrices based on multiplex bead-based flow cytometry. The study aimed to evaluate the comparability of IL-6, IL-8, and IL-10 serum- and plasma-based measurement results using flow cytometry.

MATERIALS AND METHODS

The serum and EDTA-K2 plasma were collected from three cohorts of hematologic malignancy patients (n = 66, 75, and 37, respectively) to evaluate comparability of IL-6, IL-8, and IL-10 measurement results using QuantoBio 14-plex cytokine kit on the BeamCyte-1026 flow cytometry. The Passing-Bablok regression was performed between serum- and plasma-based levels of cytokines. Additionally, the relative deviation of cytokine measurement results from the two matrices was compared with the allowable limits from the China National External Quality Assessment cytokine program.

RESULTS

The results revealed a relatively high correlation in IL-6, IL-8, and IL-10 levels between serum and plasma, with correlation coefficients of 0.966, 0.924, and 0.985, respectively. However, the comparability in the two matrices was unsatisfactory. Compared to plasma, the relative deviation of IL-6, IL-8, and IL-10 in serum was 74.8 %, -29.3 %, and 46.5 %, respectively, and only 20 % (IL-6), 31 % (IL-8), and 38 % (IL-10) of samples met allowable limits.

CONCLUSIONS

Poor comparability was found between serum- and plasma-based measurement results. Moreover, given the great potential of cytokine profiling in diagnosing and treating diseases, there is an urgent need to develop accurate and consistent processing of samples of cytokine assays to improve the accuracy and reproducibility of results and ensure the specimen's fitness for purpose.

Comparability of sample results and commutability of reference materials among different measurement procedures for protein C activity assays

BACKGROUND AND AIMS

Several types of measurement procedures (MPs) for protein C activity assays are currently available. Clinical sample (CS) results among different MPs should be comparable. The commutability of reference materials (RMs) is an essential requirement to achieve comparability of CS results.

MATERIALS AND METHODS

Considering the total error calculated using reliable biological variation (BV) data and external quality assessment (EQA) criteria, we chose the allowable limits of comparability and criterion of commutability. According to Clinical and Laboratory Standardization Institute EP9 and our previous studies, 92 CSs were used to evaluate the comparability among the three MPs (Sysmex CS-5100, IL ACL TOP 700, and STA-R Evolution). The difference in bias method recommended by International Federation of Clinical Chemistry and Laboratory Medicine was used to assess the commutability of six RMs, including World Health Organization (WHO) IS 02/342.

RESULTS

The compliance rates of CSs were 94.6-100% with the corresponding calibration mode. WHO IS, HemosIL calibration plasma, and candidate RMs, PC20201 and PC20202, were commutable between each pair of the three MPs.

CONCLUSION

It is feasible to set the allowable limits of comparability and the criterion of commutability based on the BV and EQA criteria.