Objective: To delineate differences in lymphocyte subset expression between patients with infectious pneumonia and immune-related interstitial lung disease (IRILD), to assess the immune status across distinct pneumonia types, and to provide novel laboratory markers through immunological profiling to effectively differentiate pneumonias.
Methods: A total of 78 patients sequentially enrolled from Peking University People' s Hospital between January 2023 and March 2024 were stratified into three groups: 27 with infectious pneumonia, 27 with isolated immune-related interstitial lung disease (IRILD), and 24 with IRILD complicated by infection. Fifty age-matched healthy individuals undergoing routine physical examinations during the same period served as controls. Peripheral lymphocyte subsets were quantified in all subjects by multiparametric flow cytometry.
Results: There was no statistically significant difference in age between the pneumonia patients and the healthy control group in this study (P>0.05). Analysis of laboratory parameters revealed that compared with the IRILD group, the infectious pneumonia group demonstrated significantly elevated levels of neutrophils, C-reactive protein, procalcitonin (PCT), erythrocyte sedimentation rate (ESR), D-dimer, and fibrinogen (P < 0.05), while the IRILD with superimposed infection group exhibited significantly increased levels of PCT, ESR, and immunoglobulin G (P < 0.05). At the lymphocyte subset level, compared with the control group, the infectious pneumonia group exhibited significantly decreased counts of T cells, B cells, natural killer (NK) cells, CD4+T cells, and the CD4+/CD8+ ratio (P < 0.05). Similarly, compared with the control group, the IRILD group showed significantly reduced counts of T cells, B cells, CD4+T cells, and the CD4+/CD8+ ratio (P < 0.05). Furthermore, compared with the control group, the IRILD-with-infection group demonstrated significantly lower counts of T cells, B cells, NK cells, CD4+T cells, and CD8+T cells (P < 0.05). Compared with the IRILD group, the infectious pneumonia group had a significantly lower NK cell count (P < 0.05). Additionally, compared with the IRILD group, the IRILD-with-infection group displayed significantly reduced counts of NK cells and CD8+T cells (P < 0.05).
Conclusion: The study revealed significant variations in lymphocyte subset profiles among the distinct pneumonia groups, providing novel insights with potential diagnostic value for differentiating between pneumonia types.
目的: 比较感染性肺炎和免疫相关间质性肺病(immune-related interstitial lung disease, IRILD)患者淋巴细胞亚群表达的差异，评估不同肺炎患者的免疫状态，从免疫学的角度为有效鉴别不同肺炎提供新的实验室指标。
方法: 连续纳入2023年1月至2024年3月就诊于北京大学人民医院风湿免疫科的感染性肺炎患者27例、单纯IRILD患者27例以及IRILD合并感染患者24例，并选择同期进行体检的50名健康志愿者作为对照组。采用流式细胞术检测各组淋巴细胞亚群水平。
结果: 病例组与对照组间年龄差异无统计学意义(P>0.05)。在实验室指标方面，与IRILD组相比，感染性肺炎组患者中性粒细胞、C反应蛋白、降钙素原(procalcitonin，PCT)、红细胞沉降率(erythrocyte sedimentation rate，ESR)、D-二聚体、纤维蛋白原水平增高(P＜0.05)，IRILD合并感染组患者PCT、ESR、免疫球蛋白G水平增高(P＜0.05)。在淋巴细胞亚群水平方面，与对照组相比，感染性肺炎组患者的T、B、自然杀伤(natural killer，NK)、CD4+T细胞数，CD4+/CD8+比值明显降低(P＜0.05)，IRILD组患者的T、B，CD4+T细胞数、CD4+/CD8+比值明显降低(P＜0.05)，IRILD合并感染组患者T、B、NK、CD4+T、CD8+T细胞数明显降低(P＜0.05)。与IRILD组患者相比，感染性肺炎组患者NK细胞数明显下降(P＜0.05)，IRILD合并感染组患者NK、CD8+T细胞数明显降低(P＜0.05)。
结论: 不同肺炎淋巴细胞亚群水平存在一定差异，为有效鉴别不同肺炎提供了新的思路。
Keywords: Immune-related interstitial lung disease; Infectious pneumonia; Lymphocyte subpopulations.