Young donors are associated with a lower cumulative incidence of acute graft‐vs‐host disease (aGVHD) after allogenic haematopoietic stem cell transplantation (allo‐HSCT) than old donors. Although grafts are harvested from healthy donors, it is unclear whether donor age is associated with aGVHD occurrence owing to its effect on cell compositions in grafts. Moreover, the differences in monocyte subsets in grafts between young and old donors and the association between monocyte subsets in bone marrow (BM) grafts and aGVHD remain to be elucidated. In the current study, non‐classical monocytes and the CD4⁺/CD8⁺ T cell ratio were remarkably decreased in BM grafts in donors <30 years old. Multivariate analysis further revealed that the level of non‐classical monocytes in BM grafts (≥0.31 × 10⁶/kg) was an independent risk factor for the occurrence of II‐IV aGVHD. In summary, our data indicate that non‐classical monocytes in BM grafts may help identify patients at high risk for aGVHD after allo‐HSCT. Although further validation is required, our results suggest that the low level of non‐classical monocytes and a low ratio of CD4⁺/CD8⁺ T cell in BM grafts may be correlated with the lower incidence of aGVHD in young donors.

中文翻译：

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骨髓移植物中的单核细胞亚群可能导致年轻供体的急性移植物抗宿主病发生率低。

与老年供体相比，年轻供体在同种异体造血干细胞移植 (allo-HSCT) 后急性移植物抗宿主病 (aGVHD) 的累积发生率较低。尽管移植物是从健康供体中获得的，但由于其对移植物中细胞组成的影响，尚不清楚供体年龄是否与 aGVHD 的发生有关。此外，年轻和年老供体之间移植物中单核细胞亚群的差异以及骨髓 (BM) 移植物中单核细胞亚群与 aGVHD 之间的关联仍有待阐明。在目前的研究中，非经典单核细胞和 CD4 ⁺ /CD8 ⁺<30岁供体的BM移植物中T细胞比率显着降低。多变量分析进一步表明，BM移植物中非经典单核细胞的水平（≥0.31×10 ⁶ /kg）是发生II-IV aGVHD的独立危险因素。总之，我们的数据表明，BM 移植物中的非经典单核细胞可能有助于识别 allo-HSCT 后发生 aGVHD 的高风险患者。虽然需要进一步验证，但我们的结果表明，BM 移植物中非经典单核细胞的低水平和 CD4 ⁺ /CD8 ⁺ T 细胞的低比率可能与年轻供体的 aGVHD 发生率较低有关。