Abstract: Objectives To assess the recover cells from Leukocyte reduction filters (LRFs) and their related factors, this study analyzed the number of natural killer (NK) cells and T cells from LRFs and whole blood (WB). The correlation between the number of these cells and age, sex and other factors was further analyzed. Methods WB and LRFs (400 mL) were collected from 51 repeat blood donors in Shenzhen Blood Center from July 2023 to June 2024. White blood cells (WBCs) were obtained by washing LRFs with PBS buffer. The cells from WB and LRFs were counted by blood cell analyzer. Mononuclear cells were isolated by density gradient centrifugation. The proportions of CD3^-CD56⁺NK, CD3⁺CD4⁺T and CD3⁺CD8⁺T cells were detected by flow cytometry. Statistical analysis was performed using GraphPad Prism v.9.0 software. Results In a certain flush volume, the number of total lymphocytes from LRFs increased with the increase of flush volume, but the cell density decreased with the increase of flush solution. There was no significant difference in the total number of lymphocytes from LRFs among donors of different ages and genders (P>0.05). According to the results of cell number and cell ratio, the number of CD3^-CD56⁺NK cells from LRFs was different in age groups (P<0.05), but no significant difference was found in gender groups (P>0.05). The number of CD3^-CD56⁺NK cells from WB in male donor were significantly higher than that in female donor (P>0.05). Whether from LRFs or WB, there was no significant difference in the number of CD3⁺CD4⁺T cells and CD3+CD8+T cells in different age groups and gender groups (P>0.05). Conclusion In a certain flush volume, the total number of lymphocytes from LRFs was correlated with the volume of the flush solution. The number of CD3⁺CD4⁺T cells and CD3⁺CD8⁺T cells were not significantly correlated with the age and gender of blood donor, while the number of CD3^-CD56⁺NK cells was correlated with the age of blood donor.

Key words: Leukocyte filters, NK cells, T cells