Analysis of the sugar specificity and molecular location of the beta-glucan-binding lectin site of complement receptor type 3 (CD11b/CD18).
Analysis of the sugar specificity and molecular location of the beta-glucan-binding lectin site of complement receptor type 3 (CD11b/CD18).
复制标题
DOI：
10.4049/jimmunol.156.3.1235
复制
发表时间：
1996-02
影响因子：
4.4
通讯作者：
B. P. Thornton;V. Vetvicka;M. Pitman;R. Goldman;G. D. Ross
中科院分区：
文献类型：
--
作者：
B. P. Thornton;V. Vetvicka;M. Pitman;R. Goldman;G. D. Ross
酵母多糖是酿酒酵母的细胞壁，30多年前报道其β-葡聚糖是巨噬细胞激活剂。然而，β-葡聚糖受体的身份一直存在争议。该研究表明，α M β 2-整联蛋白CR 3（Mac-1，CD 11b/CD 18）通过位于CD 11b I结构域（包含iC 3b、ICAM-1和纤维蛋白原的结合位点）外部的一个或多个凝集素位点充当β-葡聚糖受体。用FITC标记的可溶性多糖和流式细胞术分析的糖特异性表明，CR 3特异性染色与几种纯β-葡聚糖，但不与α-甘露聚糖。然而，10-kDa可溶性酵母多糖（SZP）对CR 3具有高亲和力（6.7 × 10（-8）M），主要由甘露糖和约5%葡萄糖组成。SZP-FITC或β-葡聚糖-FITC与CR 3的结合不仅被来自酵母、蘑菇、海藻或大麦的纯β-葡聚糖阻断，而且被N-乙酰基-D-葡糖胺（NADG）、α-或β-甲基甘露糖苷和α-或β-甲基-葡糖苷阻断。SZP-FITC和β-葡聚糖-FITC对所有白细胞类型的染色与抗CR 3-FITC相似，多糖-FITC染色被未标记的抗CR 3抑制≥ 95%。表达CR 3和CR 4（p150，95，CD 11 c/CD 18）之间的重组嵌合体的细胞的SZP-FITC染色表明，CD 11b的二价阳离子结合区和其C末端的区域都可以调节多糖与CR 3的结合。未标记的SZP或β-葡聚糖也阻断了11 mAb对CD 11b的C-末端结构域表位的CR 3染色，但对针对I-结构域的mAb的染色没有影响。总之，CR 3通过位于CD 11b I结构域C末端的阳离子非依赖性凝集素位点作为白细胞β-葡聚糖受体。它的糖特异性比最初认识的更广泛，允许它与含有甘露糖或NADG以及葡萄糖的某些多糖反应。
Zymosan, the cell wall from Saccharomyces cerevisiae, was reported to be a macrophage activator through its beta-glucan over 30 yr ago. Nevertheless, the identity of the beta-glucan receptor has been controversial. This study showed that the alpha M beta 2-integrin, CR3 (Mac-1, CD11b/CD18) served as the beta-glucan receptor through one or more lectin sites located outside of the CD11b I-domain that contains the binding sites for iC3b, ICAM-1, and fibrinogen. Sugar specificity, analyzed with FITC-labeled soluble polysaccharides and flow cytometry, showed CR3-specific staining with several pure beta-glucans but not with alpha-mannan. However, a 10-kDa soluble zymosan polysaccharide (SZP) with high affinity (6.7 x 10(-8) M) for CR3 consisted largely of mannose and approximately 5% glucose. Binding of either SZP-FITC or beta-glucan-FITC to CR3 was blocked not only by pure beta-glucans from yeast, mushroom, seaweed, or barley, but also by N-acetyl-D-glucosamine (NADG), alpha- or beta-methylmannoside, and alpha- or beta-methyl-glucoside. SZP-FITC and beta-glucan-FITC stained all leukocyte types similarly to anti-CR3-FITC, and polysaccharide-FITC staining was inhibited > or = 95% by unlabeled anti-CR3. SZP-FITC staining of cells expressing recombinant chimeras between CR3 and CR4 (p150,95, CD11c/CD18) suggested that both the divalent cation-binding region of CD11b and the region C-terminal to it may regulate binding of polysaccharides to CR3. Unlabeled SZP or beta-glucan also blocked CR3 staining by 11 mAb to C-terminal domain epitopes of CD11b but had no effect on staining by mAb directed to the I-domain. In conclusion, CR3 serves as the leukocyte beta-glucan receptor through a cation-independent lectin site located C-terminal to the I-domain of CD11b. Its sugar specificity is broader than originally appreciated, allowing it to react with certain polysaccharides containing mannose or NADG, as well as glucose.