Wilde C G, Seilhamer J J, McGrogan M, Ashton N, Snable J L, Lane J C, Leong S R, Thornton M B, Miller K L, Scott R W
Incyte Pharmaceuticals, Palo Alto, California 94304.
J Biol Chem. 1994 Jul 1;269(26):17411-6.
We have previously shown that human bactericidal/permeability-increasing protein (BPI) is able to inhibit serum-dependent lipopolysaccharide (LPS)-mediated activation of human monocytes and neutrophils in vitro, and to counteract the lethal effects of LPS challenge in vivo. Lipopolysaccharide-binding protein (LBP) is a serum protein which participates in LPS-mediated activation of cells (Tobias, P. S., Mathison, J., Mintz, D., Lee, J. D., Kravchenko, V., Kato, K., Pugin, J., and Ulevitch, R. J. (1992) Am. J. Respir. Cell. Mol. Biol. 7, 239-245). We have proposed that BPI functions in a negative feedback loop which opposes this activation (Marra, M. N., Wilde, C. G., Collins, M. S., Snable, J. L., Thornton, M. B., and Scott, R. W. (1992) J. Immunol. 148, 532-537). We have now cloned and expressed recombinant forms of human BPI and LBP. Here we demonstrate that purified recombinant human LBP can replace the serum requirement for both LPS binding to human monocytes and LPS-mediated secretion of tumor necrosis factor alpha from these cells. These activities of LBP are inhibited by a neutralizing anti-CD14 monoclonal antibody. We further demonstrate that purified recombinant human BPI can inhibit LBP-mediated LPS binding to cells and their subsequent activation. Comparison of the LPS binding properties of BPI and LBP in enzyme-linked immunosorbent type assays and in the Limulus amebocyte lysate assay suggest that BPI has a stronger affinity for LPS than does LBP. Direct competition between BPI and LBP for LPS may explain the inhibition by BPI of the proinflammatory effects of LBP in the presence of LPS.
我们先前已表明，人杀菌/通透性增加蛋白（BPI）能够在体外抑制血清依赖性脂多糖（LPS）介导的人单核细胞和中性粒细胞的活化，并在体内抵消LPS攻击的致死作用。脂多糖结合蛋白（LBP）是一种血清蛋白，参与细胞的LPS介导的活化（托拜厄斯，P.S.，马西森，J.，明茨，D.，李，J.D.，克拉夫琴科，V.，加藤，K.，普金，J.，和乌列维奇，R.J.（1992年）《美国呼吸细胞与分子生物学杂志》7，239 - 245）。我们提出BPI在一个负反馈回路中起作用，该回路对抗这种活化（马拉，M.N.，王尔德，C.G.，柯林斯，M.S.，斯纳布尔，J.L.，桑顿，M.B.，和斯科特，R.W.（1992年）《免疫学杂志》148，532 - 537）。我们现已克隆并表达了重组形式的人BPI和LBP。在此我们证明，纯化的重组人LBP能够替代血清，用于LPS与人单核细胞的结合以及这些细胞的LPS介导的肿瘤坏死因子α的分泌。LBP的这些活性被一种中和性抗CD14单克隆抗体所抑制。我们进一步证明，纯化的重组人BPI能够抑制LBP介导的LPS与细胞的结合及其随后的活化。在酶联免疫吸附试验和鲎试剂试验中对BPI和LBP的LPS结合特性的比较表明，BPI对LPS的亲和力比LBP更强。BPI和LBP对LPS的直接竞争可能解释了在LPS存在时BPI对LBP促炎作用的抑制。
