白蛋白可抑制血小板活化因子（PAF）诱导的血小板和巨噬细胞反应：对PAF生物活性形式的影响。

Albumin inhibits platelet-activating factor (PAF)-induced responses in platelets and macrophages: implications for the biologically active form of PAF.

Grigoriadis G, Stewart A G

Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.

Br J Pharmacol. 1992 Sep;107(1):73-7. doi: 10.1111/j.1476-5381.1992.tb14465.x.

Abstract

Platelet-activating factor (PAF) binds with high affinity to albumin leading Clay et al. (1990) to suggest that the active form of PAF is the albumin-PAF complex. 2. In the present study the proposal that albumin-bound, rather than monomeric PAF, is the active form of PAF at PAF receptors was critically evaluated by examining the effect of albumin on the potency of PAF in isolated platelets and macrophages. 3. Bovine serum albumin inhibited concentration-dependently PAF-induced responses in platelets and macrophages. The most probable explanation of this finding is that BSA reduced the concentration of free PAF. 4. Thus, we conclude that free PAF, rather than the albumin-PAF complex is the active form. Consequently, local concentrations of albumin will influence profoundly the potency of endogenously released PAF. Moreover, estimates of the affinity of PAF for PAF receptors made in buffers containing BSA, underestimate the true affinity of PAF for its receptors by approximately 3 orders of magnitude.

摘要

血小板活化因子（PAF）与白蛋白具有高亲和力结合，这使得克莱等人（1990年）提出PAF的活性形式是白蛋白-PAF复合物。2. 在本研究中，通过检查白蛋白对分离的血小板和巨噬细胞中PAF效力的影响，对PAF受体处与白蛋白结合而非单体PAF是PAF活性形式这一观点进行了严格评估。3. 牛血清白蛋白浓度依赖性地抑制血小板和巨噬细胞中PAF诱导的反应。这一发现最可能的解释是牛血清白蛋白降低了游离PAF的浓度。4. 因此，我们得出结论，游离PAF而非白蛋白-PAF复合物是活性形式。因此，白蛋白的局部浓度将深刻影响内源性释放的PAF的效力。此外，在含有牛血清白蛋白的缓冲液中对PAF与PAF受体亲和力的估计，将PAF对其受体的真实亲和力低估了约3个数量级。