Gao J X, Issekutz A C
Department of Pediatrics and Microbiology, Dalhousie University, Halifax, NS, Canada.
Immunology. 1997 Mar;90(3):448-54. doi: 10.1111/j.1365-2567.1997.00448.x.
Polymorphonuclear leucocyte (PMNL) accumulation in extravascular tissues and inflammatory exudates is dependent on their migration through blood vessel endothelium and then through connective tissue. Previously we utilized a barrier of human synovial and dermal fibroblasts (HSF or HDF) grown on microporous filters, as a model of PMNL migration through connective tissue. Those studies showed that beta 2 (CD18) and the beta 1 integrins, very late activation antigen-5 (VLA-5) and VLA-6, in part mediate this PMNL migration. Here we report that VLA-4, which can also be expressed at low levels on activated PMNL, is also involved in PMNL migration induced by C5a through fibroblast (HSF and HDF) barriers, because monoclonal antibody (mAb) to VLA-4 significantly inhibited (by 20-30%) PMNL migration. Blocking the function of CD18, VLA-5 or VLA-6 was not required for detection of the VLA-4-mediated migration. Combination treatment with mAb to VLA-4 and with mAb to VLA-5 or to VLA-6 further inhibited PMNL migration, irrespective of whether CD11/CD18 mechanisms were blocked with anti-CD18 mAb or not. Treatment of PMNL with a peptide based on the VLA-4-binding domain in the CS-1 fragment of fibronectin, but not a control peptide, inhibited PMNL migration to a comparable extent to treatment with mAb to VLA-4. A low level of VLA-4 was expressed on C5a-activated PMNL, detected by immunofluorescence flow cytometry. These results suggest that VLA-4 can be mobilized by human peripheral blood PMNL and can, in addition to VLA-5, VLA-6 and CD11/CD18 integrins, mediate PMNL migration through connective tissue. This is in marked contrast to PMNL transendothelial migration, where beta 1 integrins appear to play no significant role.
多形核白细胞（PMNL）在血管外组织和炎性渗出物中的积聚取决于它们通过血管内皮然后穿过结缔组织的迁移过程。此前，我们利用在微孔滤膜上生长的人滑膜和成纤维细胞（HSF或HDF）屏障，作为PMNL穿过结缔组织迁移的模型。这些研究表明，β2（CD18）以及β1整合素，即极晚期活化抗原-5（VLA-5）和VLA-6，部分介导了这种PMNL迁移。在此我们报告，VLA-4在活化的PMNL上也可低水平表达，它也参与C5a诱导的PMNL通过成纤维细胞（HSF和HDF）屏障的迁移，因为针对VLA-4的单克隆抗体（mAb）显著抑制（20%-30%）PMNL迁移。检测VLA-4介导的迁移并不需要阻断CD18、VLA-5或VLA-6的功能。用针对VLA-4的mAb与针对VLA-5或VLA-6的mAb联合处理可进一步抑制PMNL迁移，无论CD11/CD18机制是否用抗CD18 mAb阻断。用基于纤连蛋白CS-1片段中VLA-4结合域的肽而非对照肽处理PMNL，对PMNL迁移的抑制程度与用针对VLA-4的mAb处理相当。通过免疫荧光流式细胞术检测发现，C5a活化的PMNL上表达低水平的VLA-4。这些结果表明，VLA-4可被人外周血PMNL调动，并且除VLA-5、VLA-6和CD11/CD18整合素外，还可介导PMNL穿过结缔组织的迁移。这与PMNL跨内皮迁移形成显著对比，在跨内皮迁移中β1整合素似乎不起重要作用。
