IRMB, Univ Montpellier, INSERM, CNRS, Montpellier, France.
Laboratoire de Virologie, Centre Hospitalier-Universitaire de Montpellier, Montpellier, France.
Front Immunol. 2024 Feb 7;15:1345422. doi: 10.3389/fimmu.2024.1345422. eCollection 2024.
Granulocytes are innate immune cells that play a key role in pathogen elimination. Recent studies revealed the diversity of granulocytes in terms of phenotype and function. In particular, a subset of granulocytes identified as low-density granulocytes (LDG) has been described in physiological conditions and with increased frequencies in several pathological contexts. However, the properties of LDG are still controversial as they vary according to the pathophysiological environment. Here we investigated the heterogeneity of granulocyte populations and the potential differences in phenotype and immunomodulatory capacity between LDG and normal density granulocytes (NDG) in people living with HIV-1 (PLWH).
To this end, we developed an optimized method to purify LDG and NDG from a single blood sample, and performed in-depth, comparative phenotypic characterization of both granulocyte subtypes. We also assessed the impact of purification steps on the expression of cell surface markers on LDG by immunophenotyping them at different stages of isolation.
We identified 9 cell surface markers (CD16, CD32, CD89, CD62L, CD177, CD31, CD10, CXCR4 and CD172α) differentially expressed between LDG and NDG. Noteworthy, markers that distinguish the two subsets include receptors for the Fc part of IgG (CD16, CD32) and IgA (CD89). Importantly, we also highlighted that the purification procedure affects the expression of several cell surface markers (i.e.CD63, CD66b, …) which must be taken into account when characterizing LDG. Our work sheds new light on the properties of LDG in PLWH and provides an extensive characterization of this granulocyte subset in which Fc receptors are key discriminatory markers.
粒细胞是先天免疫细胞，在病原体清除中发挥关键作用。最近的研究揭示了粒细胞在表型和功能方面的多样性。特别是，在生理条件下已鉴定出一种称为低密度粒细胞 (LDG) 的粒细胞亚群，并且在几种病理情况下其频率增加。然而，LDG 的特性仍存在争议，因为它们根据病理生理环境而变化。在这里，我们研究了粒细胞群体的异质性以及 LDG 和正常密度粒细胞 (NDG) 之间在表型和免疫调节能力方面的潜在差异，研究对象为 HIV-1 感染者 (PLWH)。
为此，我们开发了一种从单个血液样本中纯化 LDG 和 NDG 的优化方法，并对两种粒细胞亚型进行了深入的、比较表型特征分析。我们还通过在不同的分离阶段对 LDG 进行免疫表型分析，评估了纯化步骤对 LDG 表面标志物表达的影响。
我们鉴定了 9 个细胞表面标志物 (CD16、CD32、CD89、CD62L、CD177、CD31、CD10、CXCR4 和 CD172α)，这些标志物在 LDG 和 NDG 之间表达不同。值得注意的是，区分这两个亚群的标志物包括 IgG（CD16、CD32）和 IgA（CD89）Fc 部分的受体。重要的是，我们还强调，纯化程序会影响几个表面标志物（即 CD63、CD66b、...）的表达，在对 LDG 进行特征分析时必须考虑这些标志物。我们的工作为 PLWH 中的 LDG 特性提供了新的认识，并对该粒细胞亚群进行了广泛的特征分析，其中 Fc 受体是关键的区分标志物。
