[Abnormal expression of CXCR5+CD8+ T cells and CXCL13 in severe aplastic anemia patients and their correlation with hematological parameters].

Objective: To analyze the expression of C-X-C chemokine receptor 5 (CXCR5)+CD8+ T cells and plasma C-X-C motif chemokine 13 (CXCL13) in severe aplastic anemia (SAA) patients and their correlations with hematological parameters. Methods: The clinical data of 35 SAA patients in the Hematology Department of Tianjin Medical University General Hospital from January 2018 to September 2021 were retrospectively analyzed. The patients were divided into two groups according to whether they had received the medication: untreated SAA group and recovery SAA group. In untreated group, there were 18 patients who had not received any medication, with 9 males and 9 females, and aged 51 (18-76) years. In recovery SAA group, there were 17 patients who were separated from component blood transfusion after the immunosuppressive treatment with anti-thymocyte globulin (ATG) combined with cyclosporine A (CsA), with 7 males and 10 females, and aged 46 (16-70) years. Meanwhile, 20 healthy controls were also selected, including 8 males and 12 females, and aged 45(15-72) years. Peripheral blood and bone marrow samples were collected from SAA patients, while peripheral blood samples were obtained from healthy controls. Flow cytometry was used to detect the percentage of CXCR5+CD8+ T cells in peripheral blood and bone marrow samples. The concentration of plasma CXCL13 was measured by enzyme-linked immunosorbent assay (ELISA). The correlations between the percentage of CXCR5+CD8+ T cells and the concentration of CXCL13, as well as the correlations between these two parameters and the hematological parameters were analyzed by Spearman correlation analysis. Results: The proportion of CXCR5+CD8+ T cells in the bone marrow of untreated SAA group was (4.9±2.9)%, which was higher than that of recovery SAA group (2.7±1.5)%, with a statistically significant difference (t=2.34, P=0.027). The proportion of CXCR5+CD8+ T cells in peripheral blood of untreated SAA group, recovery SAA group and healthy control group was (8.4±4.2)%, (3.8±2.3)% and (2.6±2.0)% respectively. The proportion of CXCR5+CD8+ T cells in peripheral blood of untreated SAA group was higher than that of recovery SAA group and healthy control group (both P<0.05). The plasma CXCL13 concentration in untreated SAA group was (97.2±46.8) ng/L, which was significantly higher than that in recovery SAA group [(54.9±20.9) ng/L] and healthy control group [(47.6±17.3) ng/L] (both P<0.05). The proportion of CXCR5+CD8+ T cells in peripheral blood of SAA patients was positively correlated with the concentration of plasma CXCL13 (r=0.545, P<0.001). The proportion of peripheral blood CXCR5+CD8+ T cells in SAA patients was negatively correlated with white blood cell count, platelets count, percentage of neutrophils, absolute neutrophils count, percentage of reticulocytes, absolute reticulocytes count, bone marrow myeloid cells, bone marrow erythroid cells and megakaryocytes count (r=-0.556, -0.392, -0.617, -0.615, -0.395, -0.543, -0.432, -0.484 and -0.523, all P<0.05). The proportion of peripheral blood CXCR5+CD8+ T cells was positively correlated with the percentage of peripheral blood lymphocytes and bone marrow lymphoid cells (r=0.593 and 0.556, both P<0.05). Meanwhile, the concentration of plasma CXCL13 in SAA patients was negatively correlated with white blood cell count, absolute neutrophils count, percentage of reticulocytes, absolute reticulocytes count and bone marrow myeloid cells (r=-0.447, -0.446, -0.498, -0.407 and -0.456, all P<0.05), but positively correlated with bone marrow lymphoid cells (r=0.384, P<0.05). Conclusions: The proportion of CXCR5+CD8+ T cells and the concentration of plasma CXCL13 increases in SAA patients. The proportion of CXCR5+CD8+ T cells in peripheral blood is positively correlated with the concentration of CXCL13. Moreover, the proportion of CXCR5+CD8+ T cells and the concentration of CXCL13 are correlated with many hematological parameters, which may play a critical role in the immune pathogenesis of SAA.目的： 分析重型再生障碍性贫血（SAA）患者C-X-C趋化因子受体5（CXCR5）+CD8+ T细胞比例和血浆C-X-C基序趋化因子13（CXCL13）的表达水平，及其与血液学指标的相关性。 方法： 回顾性分析2018年1月至2021年9月天津医科大学总医院35例SAA患者的临床资料，根据患者是否接受过药物治疗，将患者分为2组：（1）初治SAA组：18例，患者未接受过药物治疗；其中男9例，女9例，年龄51（18~76）岁；（2）缓解期SAA组：17例，指经抗胸腺细胞球蛋白（ATG）联合环孢素A（CsA）免疫抑制治疗后，脱离成分血输注的患者；其中男7例，女10例，年龄46（16~70）岁。另外选取20名健康对照者，其中男8名，女12名，年龄45（15~72）岁。收集SAA患者外周血及骨髓标本，同时收集健康对照者外周血标本。采用流式细胞术检测外周血及骨髓标本中CXCR5+CD8+ T细胞比例，采用酶联免疫吸附试验检测血浆中CXCL13表达水平。CXCR5+CD8+ T细胞比例与CXCL13表达水平的相关性以及二者与血液学指标的相关性采用Spearman相关性分析。 结果： 初治SAA组骨髓CXCR5+CD8+ T细胞比例为（4.9±2.9）%，高于缓解期SAA组的（2.7±1.5）%（t=2.34，P=0.027）。初治SAA组、缓解期SAA组和健康对照组外周血CXCR5+CD8+ T细胞比例分别为（8.4±4.2）%、（3.8±2.3）%、（2.6±2.0）%，初治SAA组外周血CXCR5+CD8+ T细胞比例高于缓解期SAA组和健康对照组（均P<0.05）。初治SAA组血浆CXCL13表达水平为（97.2±46.8）ng/L，高于缓解期SAA组的（54.9±20.9）ng/L和健康对照组的（47.6±17.3）ng/L（均P<0.05）。SAA患者外周血CXCR5+CD8+ T细胞比例与CXCL13表达水平呈正相关（r=0.545，P<0.001）。SAA患者外周血CXCR5+CD8+ T细胞比例与白细胞、血小板、中性粒细胞百分比、中性粒细胞绝对值、网织红细胞百分比、网织红细胞绝对值、骨髓粒系百分比、骨髓红系百分比、骨髓巨核细胞数量均呈负相关（r=-0.556、-0.392、-0.617、-0.615、-0.395、-0.543、-0.432、-0.484、-0.523，均P<0.05），与外周血淋巴细胞百分比和骨髓淋系百分比均呈正相关（r=0.593、0.556，均P<0.05）。SAA患者外周血中CXCL13表达水平与白细胞、中性粒细胞绝对值、网织红细胞百分比、网织红细胞绝对值、骨髓红系百分比呈负相关（r=-0.447、-0.446、-0.498、-0.407、-0.456，均P<0.05），与骨髓淋系百分比呈正相关（r=0.384，P<0.05）。 结论： SAA患者CXCR5⁺CD8⁺ T细胞比例及血浆CXCL13表达水平增高。外周血CXCR5+CD8+ T细胞比例与CXCL13表达水平呈正相关，二者均与多项血液学指标具有相关性，可能在SAA免疫发病机制中具有重要作用。.