INTRODUCTION The clinical significance and prognostic value of T cell involvement and programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) have not been established in lymphocytic fulminant myocarditis (FM). We investigated the prognostic impact of the number of CD4+, CD8+, FoxP3+, and PD-1+ T cells, as well as PD-L1 expression, in cardiomyocytes in lymphocytic FM. METHODS This is a single-center observational cohort study. Myocardial tissue was obtained from 16 consecutive patients at lymphocytic FM onset. The median follow-up was 140 days. Cardiac events were defined as a composite of cardiac death and left ventricular-assist device implantation. CD4, CD8, FoxP3, PD-1, and PD-L1 immunostaining was performed on myocardial specimens. RESULTS The median age of the patients was 52 years (seven men and nine women). There was no significant difference in the number of CD4+ cells. The number of CD8+ cells and the CD8+/CD4+ T cell ratio were higher in the cardiac event group (Event+) than in the group without cardiac events (Event-) (P = 0.048 and P = 0.022, respectively). The number of FoxP3+ T cells was higher in the Event+ group (P = 0.049). Although there was no difference in the number of PD-1+ cells, cardiomyocyte PD-L1 expression was higher in the Event+ group (P = 0.112). Event-free survival was worse in the group with a high CD8+ cell count (P = 0.012) and high PD-L1 expression (P = 0.049). When divided into three groups based on the number of CD8+ cells and PD-L1 expression (CD8highPD-L1high [n = 8], CD8lowPD-L1high [n = 1], and CD8lowPD-L1low [n = 7]), the CD8highPD-L1high group demonstrated the worst event-free survival, while the CD8lowPD-L1high group had a favorable prognosis without cardiac events (P = 0.041). CONCLUSION High myocardial expression of CD8+ T cells and PD-L1 may predict a poor prognosis in lymphocytic FM.

中文翻译：

---

心肌中 CD8 阳性 T 细胞和 PD-L1 表达的平衡可预测淋巴细胞暴发性心肌炎的预后。

简介 T 细胞受累和程序性细胞死亡 1 (PD-1)/程序性细胞死亡配体 1 (PD-L1) 在淋巴细胞暴发性心肌炎 (FM) 中的临床意义和预后价值尚未确定。我们研究了淋巴细胞 FM 心肌细胞中 CD4+、CD8+、FoxP3+ 和 PD-1+ T 细胞的数量以及 PD-L1 表达对预后的影响。方法 这是一项单中心观察性队列研究。心肌组织取自 16 名连续发生淋巴细胞性 FM 的患者。中位随访时间为 140 天。心脏事件被定义为心源性死亡和左心室辅助装置植入的复合事件。对心肌标本进行 CD4、CD8、FoxP3、PD-1 和 PD-L1 免疫染色。结果 患者的中位年龄为 52 岁（7 名男性和 9 名女性）。CD4+细胞数量没有显着差异。心脏事件组（Event+）的 CD8+ 细胞数量和 CD8+/CD4+ T 细胞比值高于无心脏事件组（Event-）（分别为 P = 0.048 和 P = 0.022）。Event+ 组中 FoxP3+ T 细胞的数量较高 (P = 0.049)。尽管 PD-1+ 细胞数量没有差异，但 Event+ 组心肌细胞 PD-L1 表达较高（P = 0.112）。CD8+ 细胞计数高 (P = 0.012) 和 PD-L1 表达高 (P = 0.049) 组的无事件生存率更差。根据 CD8+ 细胞数量和 PD-L1 表达分为三组（CD8highPD-L1high [n = 8]、CD8lowPD-L1high [n = 1] 和 CD8lowPD-L1low [n = 7]），CD8highPD- L1high 组的无事件生存期最差，而 CD8lowPD-L1high 组的预后良好，无心脏事件（P = 0.041）。结论 心肌 CD8+ T 细胞和 PD-L1 的高表达可能预示着淋巴细胞 FM 的不良预后。