Calcium signaling in dendritic cells by human or mycobacterial Hsp70 is caused by contamination and is not required for Hsp70-mediated enhancement of cross-presentation
Calcium signaling in dendritic cells by human or mycobacterial Hsp70 is caused by contamination and is not required for Hsp70-mediated enhancement of cross-presentation
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DOI：
10.1074/jbc.m803310200
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发表时间：
2008-09-26
影响因子：
4.8
通讯作者：
Noessner, Elfriede
中科院分区：
文献类型：
--
作者：
Bendz, Henriette;Marincek, Boris-Christian;Noessner, Elfriede
细胞外热休克蛋白（HSP）可以刺激抗原特异性免疫反应。使用重组人（rhu）Hsp70，我们以前证明，通过与外源性抗原肽形成复合物，rhuHsp70可以增强抗原呈递细胞（APC）的交叉呈递，从而产生更强的T细胞刺激。还描述了分枝杆菌（myc）Hsp70的T细胞刺激活性。据报道，MycHsp70辅助的T细胞活化通过mycHsp70与趋化因子受体5（CCR5）的结合、钙信号传导、表型成熟和树突状细胞（DC）的细胞因子分泌起作用。我们报告，高度纯化的rhuHsp70和mycHsp70蛋白都强烈增强外源性抗原的交叉呈递。不同的APC，无论CCR5的表达增强交叉呈递。此外，纯化的Hsp70蛋白在APC中均不诱导钙信号。相反，发现钙信号传导活性是由Hsp70蛋白制剂中存在的污染核苷酸引起的。这些结果反驳了mycHsp70蛋白需要CCR5表达和APC的钙信号传导以增强T细胞刺激的抗原交叉呈递的假设。
Extracellular heat shock proteins (HSPs) can stimulate antigen-specific immune responses. Using recombinant human (rhu) Hsp70, we previously demonstrated that through complex formation with exogenous antigenic peptides, rhuHsp70 can enhance cross-presentation by antigen-presenting cells (APCs) resulting in stronger T cell stimulation. T cell stimulatory activity has also been described for mycobacterial (myc) Hsp70. MycHsp70-assisted T cell activation has been reported to act through the binding of mycHsp70 to chemokine receptor 5 (CCR5), calcium signaling, phenotypic maturation, and cytokine secretion by dendritic cells (DCs). We report that highly purified rhuHsp70 and mycHsp70 proteins both strongly enhance cross-presentation of exogenous antigens. Augmentation of cross-presentation was seen for different APCs, irrespective of CCR5 expression. Moreover, neither of the purified Hsp70 proteins induced calcium signals in APCs. Instead, calcium signaling activity was found to be caused by contaminating nucleotides present in Hsp70 protein preparations. These results refute the hypothesis that mycHsp70 proteins require CCR5 expression and calcium signaling by APCs for enhanced antigen cross-presentation for T cell stimulation.