目的：研究重度抑郁症（MDD）患者体内免疫细胞的变化，以及炎症和吸烟对MDD患者免疫细胞占比的 影响。方法：选择 GEO 数据库（GSE19738）中 33 例 MDD 患者和 34 例健康对照的数据为研究对象，利用 CIBERSORT计算并比较MDD患者和健康对照的免疫细胞成分；并分析炎症和吸烟对MDD患者免疫细胞占 比的影响。结果：通过CIBERSORT法分析得到免疫细胞共包括22种免疫亚型，MDD患者体内单核细胞的含 量相比健康对照人群出现显著下降（P＜0.05）。脂多糖（LPS）刺激后MDD患者的CD8+T细胞占比明显高于健 康对照人群（P＜0.05），浆细胞占比明显低于健康对照人群（P＜0.05）。吸烟MDD患者的CD8+T细胞占比明 显高于戒烟患者的CD8+T细胞占比（P＜0.05），吸烟患者与戒烟患者相比，CCL5、ORM1、GPR84、GDNF基因 的表达明显升高。结论：CD8+T细胞可能在MDD的发病中起到重要作用。

To study the proportion of immune cells in patients with major depressive disorder (MDD) and in healthy controls, and to analyze the influence of inflammation and smoking on immune cell proportions. Methods: The GEO database (GSE19738) was used to select 33 patients with MDD and 34 healthy controls. We used CIBERSORT analysis to calculate and compare the immune cell composition of the MDD patients and healthy controls. The effect of inflammation and smoking on immune cell proportions in MDD patients was studied. Results: CIBERSORT analysis revealed 22 kinds of immune cells, and the proportion of monocytes in MDD patients was significantly lower than that in healthy controls (P<0.05). Following lipopolysaccharide (LPS) stimulation, the proportion of CD8+ T cells in patients with MDD was significantly higher (P<0.05) and that of plasma cells was significantly lower (P<0.05) than those in healthy controls. The proportion of CD8+ T cells in smoking patients was significantly higher than that in patients who quit smoking (P<0.05). Smoking patients showed greater expression of CCL5, ORM1, GPR84, and GDNF genes compared to those who quit smoking. Conclusion: CD8+ T cells may play an important role in the pathogenesis of MDD.