Effect of Different Storage Conditions and Different Detection Time on the Results of Programmed Cell Death Protein 1 by Flow Cytometry

BACKGROUND: This study aimed to analyze the effect of different storage conditions and different detection time on the results of programmed cell death protein 1 (PD-1) in clinical peripheral blood samples by flow cytometry (FCM) after the completion of all procedure steps. METHODS: 68 inpatients were randomly selected at the First Affiliated Hospital of Anhui Medical University in March 2025, and 68 peripheral blood specimens were collected. After all laboratory procedure steps were completed, cell suspension in PBS was prepared and stored both at 4℃ and at room temperature away from light, which were then divided into four different detection time groups: 0 hours, 4 hours, 8 hours, and 24 hours groups. The percentage results of seven cell populations, CD45+ Lym cell population (CD45+ Lym cells), CD3+ T cell popu-lation (CD3+ T cells), CD3+ CD4+ T cell population (CD3+ CD4+ T cells), CD3+ CD8+ T cell population (CD3+ CD8+ T cells), CD3+PD-1+ T cell population (CD3+ PD-1+ T cells), CD3+ CD4+ PD-1+ T cell population (CD3+ CD4+ PD-1+ T cells), and CD3+ CD8+ PD-1+ T cell population (CD3+ CD8+ PD-1+ T cells), were detected using FCM. Statistical software was used to compare and analyze the results. RESULTS: When stored at 4℃ away from light, compared with 0 hours group, the results of seven cell populations in the 4 hours and 8 hours groups did not change significantly and the results of the 24 hours group decreased significantly (p < 0.05). At room temperature away from light, the results of seven cell populations had no significant difference between the 0 hours and 4 hours groups. The results of seven cell populations in the 8 hours and 24 hours groups decreased significantly, with significant difference (p < 0.05). CONCLUSIONS: The detection of PD-1 should not be carried out too long after all of the laboratory procedure steps have been completed. If samples are stored at 4℃ away from light, the detection time should be limited to 8 hours; if stored at room temperature away from light, the detection time should be limited to 4 hours. This is to ensure the accuracy and stability of the detection results.