Antczak Adam J, Vieth Joshua A, Singh Navinderjit, Worth Randall G
Department of Medical Microbiology and Immunology, University of Toledo College of Medicine, Toledo, Ohio 43614, USA.
Clin Vaccine Immunol. 2011 Feb;18(2):210-6. doi: 10.1128/CVI.00296-10. Epub 2010 Dec 22.
Platelets are crucial elements for maintenance of hemostasis. Other functions attributable to platelets are now being appreciated, such as their role in inflammatory reactions and host defense. Platelets have been reported to bind immunological stimuli like IgG complexes, and for nearly 50 years it has been speculated that platelets may participate in immunological reactions. Platelets have been reported to bind and internalize various substances, similar to other leukocytes, such as macrophages and dendritic cells. In the present study, we tested the hypothesis that human platelets can bind and internalize IgG-coated particles, similar to leukocytes. To this end, we observed that interaction with IgG-coated beads resulted in platelet activation (as measured by CD62P expression), internalization of targets, and significant soluble CD40 ligand (sCD40L) and RANTES (regulated upon activation, normal T cell expresses and secreted) secretion. Blocking FcγRIIA with monoclonal antibody (MAb) IV.3 or inhibiting actin remodeling with cytochalasin D inhibited platelet activation, internalization, and cytokine production. These data suggest that platelets are capable of mediating internalization of IgG-coated particles, resulting in platelet activation and release of both sCD40L and RANTES.
血小板是维持止血的关键要素。现在人们也认识到血小板的其他功能，比如它们在炎症反应和宿主防御中的作用。据报道，血小板能结合免疫刺激物，如IgG复合物，近50年来一直有人推测血小板可能参与免疫反应。据报道，血小板能像其他白细胞（如巨噬细胞和树突状细胞）一样结合并内化各种物质。在本研究中，我们检验了一个假设，即人类血小板能像白细胞一样结合并内化IgG包被的颗粒。为此，我们观察到与IgG包被的珠子相互作用会导致血小板活化（通过CD62P表达来衡量）、靶标的内化以及可溶性CD40配体（sCD40L）和RANTES（活化时表达和分泌，正常T细胞表达和分泌）的大量分泌。用单克隆抗体（MAb）IV.3阻断FcγRIIA或用细胞松弛素D抑制肌动蛋白重塑可抑制血小板活化、内化和细胞因子产生。这些数据表明血小板能够介导IgG包被颗粒的内化，从而导致血小板活化以及sCD40L和RANTES的释放。
