SOLUBLE COMPLEMENT RECEPTOR-TYPE-1 (CD35) IS RELEASED FROM LEUKOCYTES BY SURFACE CLEAVAGE
SOLUBLE COMPLEMENT RECEPTOR-TYPE-1 (CD35) IS RELEASED FROM LEUKOCYTES BY SURFACE CLEAVAGE
复制标题
DOI：
10.1002/eji.1830241123
复制
发表时间：
1994-11-01
影响因子：
5.4
通讯作者：
SCHIFFERLI, JA
中科院分区：
文献类型：
--
作者：
DANIELSSON, C;PASCUAL, M;SCHIFFERLI, JA
人血浆中补体受体1型的可溶性形式（sCR1）可能与受体在细胞表面的蛋白水解裂解脱落相对应。建立了一种新的酶联免疫吸附试验（ELISA），利用兔多克隆抗体特异性检测膜结合的CR1，该抗体针对CR1胞内结构域c端序列对应的19个氨基酸的肽段（mCR1-ELISA）。该酶联免疫吸附试验以剂量依赖的方式测定溶化红细胞膜、多形核白细胞（PMN）、B淋巴细胞系和肾足细胞来源的尿囊的CRI。相反，与缺乏细胞内CR1结构域的重组可溶性CR1类似，血浆中的sCR1不被识别，这表明sCR1对应于整个CR1的细胞外片段。在体外，PMN可以释放一种可溶性形式的CR1，这种CR1在mCR1-ELISA中也不能被识别，并且其大小比PMN细胞膜的CR1小（5 kDa）。可溶性CR1的释放在PMN和HL60细胞中最高，其次是U937细胞和3种不同的B淋巴细胞系，而T淋巴细胞系不释放可溶性CR1。PMN中CR1基因的表达水平也高于剩余的血液白细胞和上述测试的不同细胞系。PMN与甲酰基-蛋氨酸-酰基-苯丙氨酸、肿瘤坏死因子- α或脂多糖孵育可加速可溶性CR1的释放，与粒细胞/巨噬细胞集落刺激因子孵育可导致CR1基因持续表达和更高的可溶性CR1总释放。我们的研究结果表明，可溶性CRI是通过细胞表面CR1的切割产生的，并且大部分人血浆中CR1是从PMN中切割出来的。白细胞释放的sCR1可能在炎症部位的补体激活控制中发挥作用。
The soluble form of complement receptor type 1 in human plasma (sCR1) might correspond to the shedding of the receptor by proteolytic cleavage at the cell surface. A new enzyme-linked immunosorbent assay (ELISA) was established to specifically measure membrane-bound CR1 using a rabbit polyclonal antibody against a 19-amino acid peptide corresponding to the C-terminal sequence of the intracellular domain of CR1 (mCR1-ELISA). This ELISA measured CRI from solubilized erythrocyte membranes, polymorphonucelar leukocytes (PMN), a B lymphocyte cell line and renal podocyte-derived urinary vesicles in a dose-dependent manner. In contrast, and similarly to recombinant soluble CR1 which lacks the intracellular domain of CR1, plasmatic sCR1 was not recognized, suggesting that sCR1 corresponds to an extracellular fragment of whole CR1. In vitro, PMN were shown to release a soluble form of CR1 which was also not recognized in the mCR1-ELISA, and whose size was smaller (5 kDa) than the CR1 of PMN cell membranes. The release of soluble CR1 was highest for PMN and HL60 cells, followed by U937 cells and three different B lymphocyte cell lines, whereas T lymphocyte cell lines did not release soluble CR1. The levels of CR1 gene expression were also higher in PMN compared to remaining blood leukocytes and the different cell lines tested above. Incubation of PMN with formyl-methionyl-leucyl-phenylalanine, tumor necrosis factor-alpha or lipopolysaccharide accelerated the release of soluble CR1, and incubation with granulocyte/macrophage colony-stimulating factor resulted in sustained CR1 gene expression and higher total soluble CR1 release. Our results suggest that soluble CRI is produced by cleavage of cell surface CR1, and that a large fraction of human plasma sCR1 is cleaved from PMN. The release of sCR1 by leukocytes may play a role in the control of complement activation at sites of inflammation.