The effect of sample storage on the Peroxidation of Leukocytes Index Ratio (PLIR) measure

Abstract

Delays in processing are frequent because of problems associated with transporting the samples to the laboratory. Thus, we aimed to evaluate the effect of sample storage on the Peroxidation of Leukocytes Index Ratio (PLIR). Differences between PLIR values of lymphocytes (PLIR-L), monocytes (PLIR-M) and granulocytes (PLIR-G) were observed in fresh samples. Sample storage affected the evaluation of PLIR. In particular, PLIR-L was lower in stored samples compared to fresh samples. In conclusion, our results suggest that fresh samples are recommended for assessing the PLIR.

Figure 1

Typical dot plots FSC vs. SSC (A) and FL4 (CD45-APC) vs. SSC (B); L: lymphocytes, M: monocytes, G: granulocytes, D: dead cells and/or debris. Typical dot plots Derived (FL1/FL2) vs. FL4 of cells un-stimulated (UNST) (C) or treated with PMA (1 μg/ml) (D) or AAPH (10 mM) (E and F) for 30 min.

Figure 2

Raw data of PLIR values of lymphocytes (L), monocytes (M) and granulocytes (G), measured in fresh samples or samples stored at 18–22°C or 4–8°C for 24 h (A). Comparisons for factor sample within L: †p < 0.05, ‡p < 0.01; within M: §p < 0.01. Comparisons for factor cell within sample: L versus G or M **p < 0.01, ***p < 0.001. Typical dot plots Derived (FL1/FL2) versus SSC of L, M, and G from samples stored at 4–8°C for 24 h, un-stimulated (UNST) (B) or treated with Trolox (10 μM) (C), AAPH (10 mM) (D) or PMA (1 μg/ml) (E). D: dead cells and/or debris.