Yu B, Wright S D
Laboratory of Cellular Physiology and Immunology, Rockefeller University, New York, New York 10021, USA.
J Inflamm. 1995;45(2):115-25.
CD14 is a glycosylphosphatidyl-inositol (GPI)-linked, 55 kDa protein that binds bacterial lipopolysaccharide (LPS, endotoxin) and plays a key role in mediating cellular responses to this potent inflammatory stimulus. Binding of LPS to CD14 is facilitated by serum proteins such as LPS binding protein (LBP). To determine if there are additional plasma proteins that bind to CD14, plasma was passed over immobilized CD14 in the presence or absence of LPS, and retained proteins were eluted. This procedure isolated not only LBP but also a serum protein known as Mac-2-binding protein (Mac-2-BP), a 97 kDa species without a known function. Binding of both LBP and Mac-2-BP to CD14 required the simultaneous presence of LPS. Experiments with purified Mac-2-BP showed that this protein alone neither enabled responses of CD14-bearing cells to LPS nor blocked the ability of plasma to enable responses of CD14-bearing cells to LPS. However, Mac-2-BP did slow the neutralization of LPS mediated by plasma lipoprotein. These studies describe the first potential function for Mac-2-BP, and suggest that neutralization of LPS in plasma may be controlled by proteins in addition to LBP and CD14.
CD14是一种糖基磷脂酰肌醇（GPI）连接的55 kDa蛋白质，它能结合细菌脂多糖（LPS，内毒素），并在介导细胞对这种强效炎症刺激的反应中起关键作用。血清蛋白如LPS结合蛋白（LBP）可促进LPS与CD14的结合。为了确定是否存在其他与CD14结合的血浆蛋白，将血浆在有或无LPS的情况下通过固定化的CD14，然后洗脱保留的蛋白质。该过程不仅分离出了LBP，还分离出了一种名为Mac-2结合蛋白（Mac-2-BP）的血清蛋白，这是一种功能未知的97 kDa物质。LBP和Mac-2-BP与CD14的结合都需要同时存在LPS。对纯化的Mac-2-BP进行的实验表明，该蛋白单独既不能使携带CD14的细胞对LPS产生反应，也不能阻断血浆使携带CD14的细胞对LPS产生反应的能力。然而，Mac-2-BP确实减缓了血浆脂蛋白介导的LPS中和作用。这些研究描述了Mac-2-BP的首个潜在功能，并表明血浆中LPS的中和作用可能除了LBP和CD14外还受其他蛋白质控制。
