Tetta C, Tropea F, Camussi G, Neri R, Wratten M L, Sereni L, Silvestro L, Franceschi C, Haeffner-Cavaillon N
Clinical and Laboratory Research Department, Bellco S.p.A., Mirandola, Modena.
Nephrol Dial Transplant. 1995;10(9):1679-88.
Platelet-activating factor is a mediator of inflammation involved in the blood-membrane interaction. We report that selective stimulation of complement receptors (CR1 and CR3) triggers PAF synthesis and monocyte adherence to complement-activating membranes.
The synthesis of PAF was studied after stimulation of normal human adherent monocytes with F(ab)2 and Fab fragments of monoclonal antibodies specific to CR1 and CR3. CD11a, CD11b, CD18, and CD35 was studied by flow cytometry on neutrophils and monocytes. The molecular species of PAF from stimulated monocytes were identified by reverse-phase high-performance liquid chromatography coupled with mass spectrometry.
Anti-CR1 and anti-CR3 monoclonal antibodies induced a dose-dependent C-16 but not C-18 PAF production. The latter occurred also with monovalent Fab fragments of both anti-CR1 and anti-CR3 monoclonal antibodies, that were not internalized as seen by immunofluorescence. Adherence of monocytes to Cuprophan membranes was markedly higher (P < 0.01) in membranes pretreated with fresh than with heat-inactivated normal plasma. However, the high adherence to fresh plasma-treated membranes was completely abrogated by coincubating the cells with Web 2170, a specific PAF receptor antagonist. This was not due to downregulation of adhesion molecules expression on leukocytes.
These studies implicate a crucial role of PAF in blood interaction with haemodialysis membranes that fix complement activated products.
血小板活化因子是参与血膜相互作用的炎症介质。我们报告，补体受体（CR1和CR3）的选择性刺激可触发血小板活化因子的合成以及单核细胞对补体激活膜的黏附。
用针对CR1和CR3的单克隆抗体的F(ab)2和Fab片段刺激正常人贴壁单核细胞后，研究血小板活化因子的合成。通过流式细胞术研究中性粒细胞和单核细胞上的CD11a、CD11b、CD18和CD35。通过反相高效液相色谱结合质谱法鉴定受刺激单核细胞产生的血小板活化因子的分子种类。
抗CR1和抗CR3单克隆抗体诱导剂量依赖性的C-16而非C-18血小板活化因子的产生。抗CR1和抗CR3单克隆抗体的单价Fab片段也会出现这种情况，免疫荧光显示它们未被内化。与热灭活的正常血浆预处理的膜相比，新鲜预处理的膜上单核细胞对铜仿膜的黏附明显更高（P<0.01）。然而，通过将细胞与特异性血小板活化因子受体拮抗剂Web 2170共同孵育，可完全消除对新鲜血浆处理膜的高黏附性。这并非由于白细胞上黏附分子表达的下调。
这些研究表明血小板活化因子在血液与固定补体活化产物的血液透析膜的相互作用中起关键作用。
