Downey G P, Doherty D E, Schwab B, Elson E L, Henson P M, Worthen G S
Department of Medicine, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado.
J Appl Physiol (1985). 1990 Nov;69(5):1767-78. doi: 10.1152/jappl.1990.69.5.1767.
Leukocytes within the circulation are in dynamic equilibrium with a marginated pool, thought to reside mainly within the pulmonary capillaries. The size discrepancy between the mean diameter of circulating leukocytes (6-8 microns) and that of the pulmonary capillaries (approximately 5.5 microns) forces the cells to deform in order to transit the capillary bed. Consequently, we investigated the hypothesis that the biophysical properties of cell size and deformability determined differential leukocyte retention in the lung. Comparison of the filtration properties of human neutrophils, lymphocytes, monocytes, platelets, and erythrocytes through polycarbonate filters (5-micron pore diameter) revealed that the largest leukocytes (neutrophils and monocytes) were retained to the greatest extent and the smaller cells (lymphocytes and platelets) the least. Undifferentiated HL-60 cells, of greater diameter than their differentiated counterparts, were also retained to a greater extent, confirming that cell size was one important determinant of retention in these model capillaries. However, compared with neutrophils, which are of similar diameter, monocytes were retained to a greater extent, suggesting that monocytes might be less deformable than neutrophils. To test this hypothesis, deformability was measured directly using the cell poker. Monocytes were found to be the stiffest, neutrophils the softest, and lymphocytes intermediate. Glutaraldehyde treatment of neutrophils markedly increased their stiffness and decreased their ability to transit the pores of the filters in vitro and the pulmonary microvasculature of rabbits without changing their adhesive properties or size. These observations support the hypothesis that biophysical properties of leukocytes (size and deformability) determine in part their ability to transit the pulmonary capillaries and may determine the magnitude of their marginated pools.
循环中的白细胞与边缘池处于动态平衡，边缘池被认为主要存在于肺毛细血管内。循环白细胞的平均直径（6 - 8微米）与肺毛细血管的直径（约5.5微米）之间的大小差异迫使细胞发生变形以便通过毛细血管床。因此，我们研究了这样一个假说，即细胞大小和可变形性的生物物理特性决定了白细胞在肺中的差异性滞留。通过聚碳酸酯滤器（孔径5微米）对人中性粒细胞、淋巴细胞、单核细胞、血小板和红细胞的过滤特性进行比较，结果显示最大的白细胞（中性粒细胞和单核细胞）滞留程度最高，而较小的细胞（淋巴细胞和血小板）滞留程度最低。未分化的HL - 60细胞直径大于其分化后的对应细胞，其滞留程度也更高，这证实了细胞大小是这些模型毛细血管中滞留的一个重要决定因素。然而，与直径相似的中性粒细胞相比，单核细胞的滞留程度更高，这表明单核细胞的可变形性可能比中性粒细胞低。为了验证这一假说，使用细胞压入仪直接测量了可变形性。结果发现单核细胞最硬，中性粒细胞最软，淋巴细胞居中。用戊二醛处理中性粒细胞显著增加了其硬度，并降低了它们在体外通过滤器孔以及在兔肺微血管中的能力，而不改变它们的黏附特性或大小。这些观察结果支持了这样的假说，即白细胞的生物物理特性（大小和可变形性）部分决定了它们通过肺毛细血管的能力，并可能决定其边缘池的大小。
