DataSheet_1_CD27+ microparticle interactions and immunoregulation of CD4+ T lymphocytes.pdf

IntroductionAplasia and hematological malignancies are treated with platelet transfusions, which can have major immunomodulatory effects. Platelet concentrates (PCs) contain many immunomodulatory elements, including the platelets themselves, residual leukocytes, extracellular vesicles, such as microparticles (MPs), cytokines and other soluble elements. Two of these components, MPs and a soluble form of CD27 (sCD27), have been shown to play a particularly important role in immune system modulation. The loss of CD27 expression is an irreversible marker of terminal effector CD3+ T-lymphocyte (TL) differentiation, and the CD27+ MPs present in PCs may maintain CD27 expression on the surface of TLs, and, thus, the activation of these cells.
MethodsIn this study, we phenotyped the CD27-expressing MPs present in PCs by microscale flow cytometry and investigated the interaction of these particles with CD4+ TLs. We cocultured MPs and PBMCs and determined the origin of the CD27 expressed on the surface of CD4+ TLs with the aid of two fluorochromes (BV510 for CD27 originating from MPs and BV786 for cellular CD27).
ResultsWe showed that the binding of CD27- expressing MPs involved the CD70 molecule, which was also present on these MPs. Finally, the maintenance of CD27 expression on the surface of TLs by sorted CD27+ MPs led to activation levels lower than those observed with other types of MPs.
DiscussionThese results for CD27-expressing MPs and their CD70-mediated targeting open up new possibilities for immunotherapy based on the use of MPs to maintain a phenotype or to target immune cells, for example. Moreover, decreasing the levels of CD27-expressing MPs in transfused platelets might also increase the chances of success for anti-CD27 monoclonal immunotherapy.

引言：再生障碍性贫血与血液系统恶性肿瘤可通过血小板输注治疗，该疗法可产生显著的免疫调节效应。血小板浓缩物（Platelet concentrates, PCs）含有多种免疫调节成分，包括血小板本身、残留白细胞、细胞外囊泡（如微粒（microparticles, MPs））、细胞因子及其他可溶性物质。其中两种成分——微粒（MPs）与可溶性CD27（soluble CD27, sCD27）——已被证实对免疫系统调控具有尤为关键的作用。CD27表达缺失是终末效应性CD3+ T淋巴细胞（T-lymphocyte, TL）分化的不可逆标志物，而血小板浓缩物中存在的CD27阳性MPs可维持TL表面的CD27表达，进而调控这些细胞的活化状态。

方法：本研究通过微量流式细胞术对血小板浓缩物中表达CD27的MPs进行表型分析，并探究了这些囊泡与CD4+ TLs的相互作用。我们将MPs与外周血单个核细胞（Peripheral blood mononuclear cells, PBMCs）共培养，并借助两种荧光染料（用于标记MPs来源CD27的BV510、用于标记细胞源性CD27的BV786）明确了CD4+ TLs表面表达的CD27的来源。

结果：本研究证实，表达CD27的MPs的结合依赖于其表面同样表达的CD70分子。最终，经分选的CD27阳性MPs对TL表面CD27表达的维持，所带来的细胞活化水平低于其他类型MPs所诱导的活化水平。

讨论：上述关于表达CD27的MPs及其CD70介导的靶向作用的研究结果，为基于MPs的免疫疗法开辟了新的可能——例如利用MPs维持细胞表型或靶向免疫细胞。此外，降低输注血小板中表达CD27的MPs水平，或许也能提升抗CD27单克隆免疫疗法的成功率。