Integrative experimental/computational approach establishes active cellular protrusion as the primary driving force of phagocytic spreading by immune cells

Human neutrophils possess the remarkable ability to deform in a rapid, controlled manner during processes such as migration through tissue and phagocytosis of pathogens. However, the fundamental mechanisms behind neutrophil motility remain incompletely understood; for instance, what drives cell deformation during phagocytosis - passive adhesive attraction or active cytoskeletal protrusion? We addressed this question by testing how changes in IgG density affected the rate of neutrophil phagocytic spreading over flat surfaces. In this case, a glass coverslip coated with IgG acted as a model pathogen surface, eliciting a strong spreading response from neutrophils. We tested spreading on four different densities of IgG, ranging from tens of molecules per square micron to tens of thousands of molecules per square micron. We imaged spreading cells using reflection interference contrast microscopy (RICM), yielding high-contrast images of cell-substrate contact regions from which we could relia...

人类中性粒细胞（Human neutrophils）具备在组织迁移、病原体吞噬等过程中快速且可控地发生形变的卓越能力。然而，中性粒细胞运动的核心机制仍未完全阐明；例如，吞噬过程中细胞形变的驱动因素究竟是被动黏附吸引，还是主动的细胞骨架突起？为解答这一问题，我们通过探究免疫球蛋白G（IgG）密度变化对中性粒细胞在平整表面上吞噬铺展速率的影响展开了相关实验。本实验中，包覆IgG的玻璃盖玻片可作为模拟病原体表面，能够触发中性粒细胞产生显著的铺展反应。我们测试了四种不同IgG密度的底物，密度范围从每平方微米数十个分子至数万个分子不等。我们采用反射干涉衬比显微镜（Reflection Interference Contrast Microscopy, RICM）对铺展中的细胞进行成像，获得了细胞-底物接触区域的高对比度图像，借此可可靠地……