Characterization of human alveolar macrophage Fc gamma receptor III: a transmembrane glycoprotein that is shed under in vitro culture conditions.
Characterization of human alveolar macrophage Fc gamma receptor III: a transmembrane glycoprotein that is shed under in vitro culture conditions.
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人肺泡巨噬细胞 Fc γ 受体 III 的表征：一种在体外培养条件下脱落的跨膜糖蛋白。
DOI：
10.1165/ajrcmb/5.4.307
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发表时间：
1991
影响因子：
6.4
通讯作者：
Looney,RJ
中科院分区：
文献类型：
--
作者：
Levy,PC;Utell,MJ;Fleit,HB;RobertsJr,NJ;Ryan,DH;Looney,RJ
已经在血液白细胞上鉴定了三类Fc+受体（FcR）：FcRl、FcRII和FcRII。最近已经鉴定了两种形式的FcR 1 II;在中性粒细胞上发现了磷脂酰肌醇连接形式，而在外周血淋巴细胞亚群上发现了该分子的跨膜形式。外周血单核细胞在其表面上表达低水平的FcRII，而FcRIII容易由组织巨噬细胞表达。本研究的目的是表征FcRIII的形式表达的正常人肺泡巨噬细胞（AM）从正常受试者的支气管肺泡灌洗。十二烷基硫酸钠聚丙烯酰胺凝胶电泳显示AM表达的FcR 1 II分子量为50 ~ 60 kD，经内切糖苷酶F酶切后为单一条带，分子量为35 kD。巨噬细胞FcRIII对磷脂酰肌醇特异性磷脂酶C的切割具有抗性。这些结果表明，AM表达的FcR 1 II是一种跨膜糖蛋白，与外周血淋巴细胞上发现的分子相似。使用1251标记的mAb 3G 8进行的Scatchard结合分析显示，AM表达与中性粒细胞上发现的相似数量的FcR 1 II（分别为73，300 ± 16，300和69，300 ± 8，500个受体位点/细胞; P= 0.73），而在FcR 1 II阳性外周血淋巴细胞上发现较少的结合位点（35，300 ± 13，900; P= 0.04）。值得注意的是，我们发现在37 ℃体外短期孵育期间，AM的FcR 1 II表达选择性地显著降低。由于蛋白水解切割的结果，受体脱落可能是在短期体外培养期间发生的表达减少的原因。已使用高度特异性抗FcR mAb在外周血白细胞中分离并表征了它们。FcRI具有约72 kD的分子量，并且具有对IgG单体的高亲和力（Ki = 108至109 M-）。还描述了两种较低亲和力的FcR，FcRI I和FcRI II。后者受体在生理条件下不结合IgG单体，但与IgG相互作用
Three classes of Fc'}'receptors (FcR) have been identified on blood leukocytes: FcRl, FcRlI, and FcRlII. Two forms of FcRlII have recently been characterized; a phosphatidylinositollinked form is found on neutrophils, whereas a transmembrane form of the molecule is found on a subset ofperipheral blood lymphocytes. Peripheral blood monocytes express low levels of FcRlII on their surface, whereas FcRIII is readily expressed by tissue macrophages. The purpose of this investigation was to characterize the form of FcRIII expressed by normal human alveolar macrophages (AM) obtained from normal subjects by bronchoalveolar lavage. We found FcRlII expressed by AM has a molecular mass of 50 to 60 kD on sodium dodecyl sulfate polyacrylamide gel electrophoresis and migrates as a single band with a molecular mass of 35 kD after digestion with endoglycosidase F. Macrophage FcRIII was resistant to cleavage by phosphatidylinositol-specific phospholipase C. These results demonstrate that FcRlII expressed by AM is a transmembrane glycoprotein similar to the molecule found on peripheral blood lymphocytes. Scatchard binding analysis using 1251-labeled mAb 3G8 showed that AM express similar numbers of FcRlII as found on neutrophils (73,300±16,300 versus 69,300±8,500 receptor sites/cell, respectively; P= 0.73), whereas fewer binding sites were found on FcRlII-positive peripheral blood lymphocytes (35,300±13,900; P= 0.04). Of note, we found expression of FcRlII by AM was selectively and dramatically reduced during short term in vitro incubation at 37 C. Receptor shedding as a result of proteolytic cleavage is probably responsible for the reduced expression that occurs during short-term in vitro culture.Three classes of human FC'Y receptors (FcR) have been described (1, 2). They have been isolated and characterized on peripheral blood leukocytes using highly specific anti-FcR mAb. FcRI has a molecular mass of approximately 72 kD and possesses a high affinity for IgG monomer (K,= 108 to 109 M"), Two lower affinity FcR have also been described, FcRlI and FcRlII. These latter receptors do not bind IgG monomer under physiologic conditions but interact with IgG