Vocanson Marc, Achachi Amine, Mutez Virginie, Cluzel-Tailhardat Magalie, Varlet Béatrice Le, Rozières Aurore, Fournier Philippe, Nicolas Jean-François
CIRI - International Center for Infectiology Research, Inserm, U1111, Université Lyon 1, 21 Avenue Tony Garnier, 69007, Lyon, France,
Exp Suppl. 2014;104:89-100. doi: 10.1007/978-3-0348-0726-5_7.
To develop an in vitro assay that recapitulates the key event of allergic contact dermatitis (ACD), that is the priming of effector T cells by hapten-presenting dendritic cells, and then allows for the sensitive detection of chemical allergens represents a major challenge. Classical human T cell priming assays (hTCPA) that have been developed in the past, using hapten-loaded monocyte-derived dendritic cells (MDDCs) as antigen-presenting cells and peripheral blood lymphocytes (PBLs) as responding cells, were not efficient to prime T cells to common allergens with moderate/weak sensitizing properties. Recent progress in the understanding of the effector and regulatory mechanisms of ACD have shown that T cell priming requires efficient uptake of allergens by immunogenic DCs and that it is controlled by several subsets of regulatory cells including CD25(+) Tregs. We therefore analyzed various parameters involved in allergen-specific T cell activation in vitro and showed that priming of allergen-specific T cells is hampered by several subsets of immune cells comprising CD1a(neg) DCs, CD25(+) T cells, and CD56(+) regulatory cells.CD4(+)CD25(+)FoxP3(+) Tregs prevented the in vitro T cell priming to moderate/weak allergens, and depletion of human PBLs in CD25(+) cells significantly increased specific T cell proliferation and IFN-γ secretion. CD56(+) cells exerted an additional control of T cell priming since co-depletion of both CD56(+) and CD25(+) cells improved the magnitude of chemical-specific T cell activation. Finally, CD1a(low) MDDCs were able to inhibit T cell activation obtained by allergen-pulsed CD1a(high) MDDC. Moreover, we showed that uptake by DC of allergen-encapsulated nanoparticles significantly increased their activation status and their ability to prompt specific T cell activation. Hence, by combining the different strategies, i.e., depletion of CD25(+) and CD56(+) cells, use of CD1a(high) MDDC, and nanoparticle encapsulation of allergens, it was possible to induce T cell priming to most of the moderate/weak allergens, including lipophilic molecules highly insoluble in culture media. Therefore, the present optimized in vitro human T cell priming assay is a valuable method to detect the sensitizing properties of chemical allergens.
开发一种体外检测方法，该方法能够重现过敏性接触性皮炎（ACD）的关键事件，即由呈递半抗原的树突状细胞启动效应T细胞，然后实现对化学过敏原的灵敏检测，这是一项重大挑战。过去开发的经典人类T细胞启动检测方法（hTCPA），使用负载半抗原的单核细胞衍生树突状细胞（MDDC）作为抗原呈递细胞，外周血淋巴细胞（PBL）作为反应细胞，对于启动T细胞针对具有中等/弱致敏特性的常见过敏原并不高效。最近在对ACD效应和调节机制的理解方面取得的进展表明，T细胞启动需要免疫原性树突状细胞有效摄取过敏原，并且它受包括CD25(+)调节性T细胞在内的几个调节细胞亚群的控制。因此，我们分析了体外过敏原特异性T细胞活化涉及的各种参数，并表明过敏原特异性T细胞的启动受到包括CD1a(neg)树突状细胞、CD25(+)T细胞和CD56(+)调节细胞在内的几个免疫细胞亚群的阻碍。CD4(+)CD25(+)FoxP3(+)调节性T细胞阻止了体外T细胞针对中等/弱过敏原的启动，并且在CD25(+)细胞中耗尽人类PBLs显著增加了特异性T细胞增殖和IFN-γ分泌。CD56(+)细胞对T细胞启动施加了额外的控制，因为同时耗尽CD56(+)和CD25(+)细胞提高了化学特异性T细胞活化的程度。最后，CD1a(low)MDDC能够抑制由过敏原脉冲的CD1a(high)MDDC获得的T细胞活化。此外，我们表明树突状细胞摄取包封过敏原的纳米颗粒显著增加了它们的活化状态以及它们促使特异性T细胞活化的能力。因此，通过结合不同策略，即耗尽CD25(+)和CD56(+)细胞、使用CD1a(high)MDDC以及对过敏原进行纳米颗粒包封，有可能诱导T细胞针对大多数中等/弱过敏原启动，包括在培养基中高度不溶的亲脂性分子。因此，目前优化的体外人类T细胞启动检测方法是检测化学过敏原致敏特性的一种有价值的方法。
