Anaphylatoxin binding and degradation by rat peritoneal mast cells. Mechanisms of degranulation and control.
Anaphylatoxin binding and degradation by rat peritoneal mast cells. Mechanisms of degranulation and control.
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DOI：
10.4049/jimmunol.145.6.1851
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发表时间：
1990-09
影响因子：
4.4
通讯作者：
Y. Fukuoka;T. Hugli
中科院分区：
文献类型：
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作者：
Y. Fukuoka;T. Hugli
放射性标记的人C3a与大鼠腹膜肥大细胞孵育，导致高水平的摄取和广泛的配体降解。细胞结合的和游离的放射性标记的人C3a都经历了大鼠肥大细胞的广泛降解，即使在0℃。我们检测了几种蛋白酶抑制剂防止大鼠肥大细胞降解放射性标记的人C3a的能力。在阻止放射性标记的人C3a降解方面，PMSF、糜蛋白酶抑制素和大豆胰蛋白酶抑制剂是最有效的。细胞结合配体的降解仅被PMSF完全抑制。这些化合物是从大鼠肥大细胞中提取的乳糜胰蛋白酶样酶(乳糜酶)的有效抑制剂。在PMSF存在下，放射性标记的人C3a与大鼠肥大细胞表面成分的化学交联显示出一条主带和两条次带。通过与从大鼠肥大细胞中分离纯化的凝乳酶的直接比较，证明主带和次带中的肥大细胞成分都与凝乳酶相关。然而，抗乳糜酶抗体和乳糜酶抑制剂都不影响C3a在大鼠肥大细胞上的脱粒活性，这种脱粒活性不依赖于C3a-乳糜酶的相互作用。我们的结论是，大鼠肥大细胞上既没有C3a特异性结合部位，也没有导致细胞激活的特异性受体。虽然人C3ade Arg在豚鼠回肠和肺组织上没有活性，但它结合并诱导大鼠肥大细胞脱颗粒，并增强大鼠皮肤的血管通透性，其浓度几乎与完整C3a相同。C3a和C3ade Arg在浓度超过10(-6)M时都能刺激肥大细胞的激活，这一事实与大鼠肥大细胞上过敏曲霉毒素的特定结合部位相抵触。推测阳离子C3a分子以分泌型和非裂解型两种方式激活大鼠肥大细胞，其机制与其他多元化合物相似。
Incubation of radiolabeled human C3a with rat peritoneal mast cells resulted in high levels of uptake and extensive degradation of the ligand. Both cell-bound and free radiolabeled human C3a underwent extensive degradation by rat mast cells even at 0 degrees C. We examined several protease inhibitors for their ability to prevent degradation of radiolabeled human C3a by the rat mast cells. The inhibitors PMSF, chymostatin, and soybean trypsin inhibitor were most effective in preventing radiolabeled human C3a degradation. Degradation of the cell-bound ligand was totally inhibited only by PMSF. These compounds are effective inhibitors of a chymotrypsin-like enzyme (chymase) extracted from rat mast cells. Chemical cross-linking of radiolabeled human C3a to surface components on the rat mast cells, in the presence of PMSF, revealed one major and two minor bands. The mast cell component in both the major and minor bands proved to be chymase-associated based on a direct comparison with purified chymase isolated from rat mast cells. However, neither antichymase antibody nor chymase inhibitors influenced the degranulating activity of C3a on rat mast cells that occur independently of the C3a-chymase interactions. We conclude that there are neither specific C3a-binding sites on rat mast cells nor specific receptors whose occupancy leads to cellular activation. Although human C3ades Arg is inactive on guinea pig ileal and lung tissue, it binds to and induces degranulation of rat mast cells, as well as enhances vascular permeability in rat skin, at concentrations nearly identical to that of intact C3a. The fact that both C3a and C3ades Arg stimulated mast cell activation, at concentrations in excess of 10(-6) M, argues against specific binding sites for the anaphylatoxin on rat mast cells. It is proposed that the cationic C3a molecule activates rat mast cells in a secretory and nonlytic manner by a nonspecific mechanism similar to that of other polybasic compounds.