Dzik S
Department of Pathology, Deaconess Hospital, Boston, MA 02215.
Transfus Med Rev. 1993 Apr;7(2):65-77. doi: 10.1016/s0887-7963(93)70125-x.
Modern leukocyte removal filters have been developed after years of refinement in design. Current filters are composite filters in which synthetic microfiber material is prepared as a nonwoven web. The filter material may be surface modified to alter surface tension or charge to improve performance. The housing design promotes effective contact of blood with the filter material and decreases shear forces. The exact mechanisms by which these filters remove leukocytes from blood components are uncertain, but likely represent a combination of both physical and biological processes whose contributions to leukocyte removal are interdependent. Small-pore microfiber webs result in barrier phenomena that permit retention of individual cells and increase the total adsorptive area of the filter. Modifications in surface charge can increase or decrease cell attraction to the fibers. Optimum interfacial surface tensions between blood cells, plasma, and filter fibers not only permit effective blood flow through small fiber pores, but also facilitate cell contact with the material. Barrier retention is a common mechanism for all modern leukocyte-removal filters and applies to all leukocyte subtypes. Because barrier retention does not depend on cell viability, it is operative for cells of any age and will retain any nondeformable cell, including whole nuclei from lymphocytes or monocytes. Barrier retention is supplemented by retention by adhesion. RBCs, lymphocytes, monocytes, granulocytes, and platelets differ in their relative adhesiveness to filter fibers. Different adhesive mechanisms are used in filters designed for RBCs compared with filters designed for platelets. Although lymphocytes, monocytes, and granulocytes can adhere directly to filter fibers, the biological mechanisms underlying cell adhesion may differ for these cell types. These differences may depend on expression of cell adhesion molecules. In the case of filtration of fresh RBCs, platelet-leukocyte interaction seems to supplement other mechanisms of leukocyte retention. The interactions of cells with biomaterials is an area of important research for implantable medical devices, artificial organs, and orthopedic, vascular, and dental prosthetics. Research in these areas is likely to contribute to improved biomaterials for blood filters. Improved techniques for the preparation of hybrid polymers and new techniques for surface modification of existing polymers will increase the technical opportunities for the development of synthetic surfaces ideally designed for leukocyte removal. It is therefore likely that the performance of leukocyte-removal filters will continue to improve. The development of cost-effective leukocyte removal filters specifically designed for use during component preparation would permit leukocyte depletion of all cellular blood components.
现代白细胞去除过滤器是经过多年设计改进后开发出来的。当前的过滤器是复合过滤器，其中合成微纤维材料被制备成非织造纤维网。过滤材料可以进行表面改性，以改变表面张力或电荷，从而提高性能。外壳设计促进血液与过滤材料的有效接触，并降低剪切力。这些过滤器从血液成分中去除白细胞的确切机制尚不确定，但可能代表了物理和生物过程的结合，它们对白细胞去除的贡献是相互依存的。小孔微纤维网会产生屏障现象，允许单个细胞滞留，并增加过滤器的总吸附面积。表面电荷的改变可以增加或减少细胞对纤维的吸引力。血细胞、血浆和过滤纤维之间的最佳界面表面张力不仅允许血液有效流过小纤维孔，还便于细胞与材料接触。屏障滞留是所有现代白细胞去除过滤器的常见机制，适用于所有白细胞亚型。由于屏障滞留不依赖于细胞活力，它对任何年龄的细胞都有效，并且会滞留任何不可变形的细胞，包括淋巴细胞或单核细胞的完整细胞核。屏障滞留还通过粘附滞留得到补充。红细胞、淋巴细胞、单核细胞、粒细胞和血小板对过滤纤维的相对粘附性各不相同。与设计用于血小板的过滤器相比，设计用于红细胞的过滤器使用了不同的粘附机制。虽然淋巴细胞、单核细胞和粒细胞可以直接粘附在过滤纤维上，但这些细胞类型的细胞粘附背后的生物学机制可能不同。这些差异可能取决于细胞粘附分子的表达。在新鲜红细胞过滤的情况下，血小板 - 白细胞相互作用似乎补充了白细胞滞留的其他机制。细胞与生物材料的相互作用是植入式医疗设备、人工器官以及骨科、血管和牙科假体等领域重要的研究方向。这些领域的研究可能有助于改进用于血液过滤器的生物材料。改进的杂化聚合物制备技术和现有聚合物表面改性的新技术将增加开发理想设计用于白细胞去除的合成表面的技术机会。因此，白细胞去除过滤器的性能可能会持续提高。开发专门设计用于成分制备过程的经济高效的白细胞去除过滤器将使所有细胞血液成分都能实现白细胞去除。
