Optimal T cell responses to Cryptococcus neoformans mannoprotein are dependent on recognition of conjugated carbohydrates by mannose receptors
Optimal T cell responses to Cryptococcus neoformans mannoprotein are dependent on recognition of conjugated carbohydrates by mannose receptors
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DOI：
10.4049/jimmunol.168.6.2872
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发表时间：
2002-03-15
影响因子：
4.4
通讯作者：
Levitz, SM
中科院分区：
文献类型：
--
作者：
Mansour, MK;Schlesinger, LS;Levitz, SM
隐球菌病是 T 细胞功能受损个体死亡的主要原因。可溶性新型隐球菌甘露蛋白 (NIP) 已成为有前途的候选疫苗，因为它们能够引发迟发型超敏反应和 Th 1 型细胞因子，这两种细胞因子对于清除这种病原酵母菌至关重要。在这项研究中，探讨了 MP 强效免疫刺激特性的机制。使用表达人巨噬细胞甘露糖受体（MMR）的中国仓鼠卵巢细胞，我们确定MP是MMR配体。从功能上来说，竞争性阻断 APC 上的多凝集素甘露糖受体 (MR) 可使来自免疫小鼠的原代 T 细胞和 MP 反应性 CD4(+) T 细胞杂交瘤 P1D6 的 MP 依赖性刺激分别减少 72% 和 99%。通过β-消除从MP中去除O-连接糖可分别抑制P1D6和原代T细胞的MP依赖性刺激89%和90%。此外，用蛋白酶 K 消化后，MP 依赖性的 P1D6 刺激被消除，表明 MP 的蛋白核心贡献了 APC 呈递的抗原部分。使用从不变链缺陷小鼠获得的 APC 也消除了 MP 对 P1D6 的刺激，证明 Ag 呈递受到 MHC 11 类限制。我们的数据表明，MP 是 MMR 的配体，T 细胞刺激可通过竞争性阻断 MR 或通过去除对识别至关重要的碳水化合物残基而受到功能性抑制。 T 细胞对 MP 的有效反应需要通过 MMR 识别末端甘露糖基团，这一证明为隐球菌 NIP 的免疫原性提供了分子基础，并为针对 MR 的疫苗接种策略提供了支持。
Cryptococcosis is a leading cause of death among individuals with compromised T cell function. Soluble Cryptococcus neoformans mannoproteins (NIP) have emerged as promising vaccine candidates due to their capacity to elicit delayed-type hypersensitivity and Th type 1-like cytokines, both critical to the clearance of this pathogenic yeast. In this study, the mechanisms responsible for the potent immunostimulatory properties of MP were explored. Using Chinese hamster ovary cells expressing human macrophage mannose receptor (MMR), we determined that MP is a MMR ligand. Functionally, competitive blockade of multilectin mannose receptors (MR) on APCs diminished MP-dependent stimulation of primary, T cells from Immunized mice and the MP-reactive CD4(+) T cell hybridoma, P1D6, by 72 and 99%, respectively. Removal of O-linked saccharides from MP by beta-elimination inhibited MP-dependent stimulation of P1D6 and primary T cells by 89 and 90%, respectively. In addition, MP-dependent stimulation of P1D6 was abrogated after digestion with proteinase K, suggesting the protein core of MP contributed the antigenic moiety presented by APC. Stimulation of P1D6 by MP also was abolished using APC obtained from invariant chain-deficient mice, demonstrating Ag presentation was MHC class 11 restricted. Our data suggest that MP is a ligand for the MMR and that T cell stimulation is functionally inhibited either by competitive blockade of MR or by removal of carbohydrate residues critical for recognition. The demonstration that efficient T cell responses to MP require recognition of terminal mannose groups by MMR provides both a molecular basis for the immunogenicity of cryptococcal NIP and support for vaccination strategies that target MR.