Recent evidence suggests that abnormalities involving CD4⁺T lymphocytes are associated with the pathophysiology of osteonecrosis (ON); however, few studies have addressed the CD4⁺T cells in ON related to sickle cell disease (SCD/ON). In addition, T cells producing multiple cytokines simultaneously are often present in the inflammatory milieu and may be implicated in the immune response observed in SCD/ON. In the present study, we aimed to characterize the functional status of CD4⁺T cells in SCD by simultaneously determining the frequency of IFN-γ⁺, IL-4⁺, and IL-17⁺ CD4⁺T in cell cultures under exogenous stimuli. Peripheral blood mononuclear cells (PB-MNCs) from 9 steady-state SCD patients, 15 SCD/ON patients, and 19 healthy controls had functional status of CD4⁺T cells analyzed. Bone marrow mononuclear cells (BM-MNCs) from 24 SCD/ON patients (SCD BM) and 18 patients with ON not related to SCD (non-SCD BM) were also analyzed. We found that PB-MNC of SCD patients with or without ON presented significantly reduced TCD4⁺, TCD8⁺, and TCD4⁺ naïve cell frequencies and increased frequency of circulating CD4⁺T cells able to simultaneously produce IFN-γ⁺/IL4⁺ and IL-17⁺/IL4⁺ compared to healthy controls. Conversely, the polyclonal stimulation of BM-MNC induced an increased frequency of CD4⁺IFN-γ⁺ and CD4⁺IL-17⁺ in SCD BM compared to non-SCD BM. The increased proportion of CD4⁺ T cells able to produce a broad spectrum of proinflammatory cytokines after a strong stimulus indicates that the immune system in SCD/ON patients presents an expressive pool of partially differentiated cells ready to take on effector function. It is possible that this increased subpopulation may extend to inflammatory sites of target organs and may contribute to the maintenance of inflammation and the pathophysiology of osteonecrosis in sickle cell disease.

中文翻译：

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镰状细胞病骨坏死患者的 CD4+ T 细胞谱和活化反应

最近的证据表明，涉及 CD4 ⁺ T 淋巴细胞的异常与骨坏死 (ON) 的病理生理学有关；然而，很少有研究涉及与镰状细胞病 (SCD/ON) 相关的 ON 中的 CD4 ⁺ T 细胞。此外，同时产生多种细胞因子的 T 细胞通常存在于炎症环境中，并且可能与 SCD/ON 中观察到的免疫反应有关。在本研究中，我们旨在通过同时测定 IFN- γ ⁺、IL-4 ⁺和 IL-17 ⁺ CD4 ⁺的频率来表征SCD中 CD4 ⁺ T 细胞的功能状态。外源刺激下细胞培养物中的 T。来自 9 名稳态 SCD 患者、15 名 SCD/ON 患者和 19 名健康对照的外周血单核细胞 (PB-MNC)分析了 CD4 ⁺ T 细胞的功能状态。还分析了来自 24 名 SCD/ON 患者 (SCD BM) 和 18 名与 SCD 无关的 ON 患者 (非 SCD BM) 的骨髓单核细胞 (BM-MNC)。我们发现有或没有 ON 的 SCD 患者的 PB-MNC 显着降低了 TCD4 ⁺、TCD8 ⁺和 TCD4 ⁺幼稚细胞频率，并增加了能够同时产生 IFN- γ ⁺ /IL4 ⁺和 IL的循环 CD4 ⁺ T 细胞的频率-17 ⁺ /IL4 ⁺与健康对照相比。相反，与非 SCD BM 相比，BM-MNC 的多克隆刺激诱导了SCD BM中 CD4 ⁺ IFN- γ ⁺和 CD4 ⁺ IL-17 ^{+ 的}频率增加。在强烈刺激后能够产生广谱促炎细胞因子的 CD4 ⁺ T 细胞比例增加表明 SCD/ON 患者的免疫系统呈现出准备承担效应功能的部分分化细胞的表达池。这种增加的亚群可能会扩展到靶器官的炎症部位，并可能有助于维持炎症和镰状细胞病中骨坏死的病理生理学。