Exploration on the method of combined morphological and flow cytometry detection of chimeric antigen receptor T cells / 中华检验医学杂志

ABSTRACT

Objective:To explore an assay that can concisely, rapidly, and accurately quantify the amount of chimeric antigen receptor (CAR)-T cells in the bone marrow or peripheral blood of patients after CAR-T cell immunotherapy by morphological analysis and flow cytometry assay, providing timely and accurate feedback for clinical treatment.Methods:We analyzed the CAR-T cell detection results in peripheral blood and bone marrow of 256 patients who received CAR-T cell immunotherapy in the Department of Hematology, Affiliated Hospital of Xuzhou Medical University from August 2016 to August 2021. All 256 patients survived more than one month after CAR-T cell infusion. Among them, there were 118 patients with multiple myeloma, 68 patients with acute lymphoblastic leukemia, and 70 patients with lymphoma. The morphological characteristics, positive rate and detection rate of CAR-T cell in peripheral blood and bone marrow were analyzed by morphological methods. The positive rate and detection rate of CAR-T in peripheral blood and bone marrow were analyzed by flow cytometry protein L detection. χ 2 test was used to comprehensively analyze the difference between the detection rate of the combined analysis of the two methods and the detection rate of the single method. Results:CAR-T cells have significant morphological characteristics, and there are obvious morphological differences from normal lymphocytes. The detection rates of CAR-T cells in peripheral blood or bone marrow by morphological methods and flow cytometry were 88.28%(226/256) and 79.29% (203/256), respectively. When the two methods were combined, the detection rate of CAR-T cells can reach 99.22%, with statistically significant difference comparing to that of single method( P<0.05). Through the analysis of the detection results of peripheral blood at different time points, it was found that the average detection rates of morphology and flow cytometry in 118 patients with multiple myeloma were 9.50% and 10.23% on the 7th day, and 13.50% and 15.19% respectively on the 15th day. On the 21st day, the average detection rates of morphology and flow cytometry were 8.00% and 10.07%, respectively. The average detection rates of morphology and flow cytometry in 68 patients with acute lymphoblastic leukemia were 12.00% and 11.22% on the 7th day, and 21.00% and 23.10% respectively on the 15th day. On the 21st day, the average detection rates of morphology and flow cytometry were 13.50% and 10.91%, respectively. The average detection rates of morphology and flow cytometry in 70 lymphoma patients were 7.50% and 10.35% on the 7th day, and 9.00% and 10.35% respectively on the 15th day. The average detection rates of morphology and flow cytometry at 21 days were 6.50% and 5.69%, respectively. The number of CAR-T cells in samples from patients with different diseases reached a peak around the 15th day. Conclusion:The detection rate of CAR-T cells from peripheral blood or bone marrow was significantly higher with the combination of the 2 methods compared to the single method.