Gabler W L, Tsukuda N
Department of Biochemistry, School of Dentistry, Oregon Health Sciences University, Portland.
Res Commun Chem Pathol Pharmacol. 1991 Nov;74(2):131-40.
Leukocyte adherence, an event critical to host defense, is reported to be dependent upon divalent cations. To test whether leukocyte binding is more influenced by the availability of Ca2+ or Mg2+, neutrophils and mononuclear leukocyte adherence to surfaces coated with differing proteins, in medium containing varying concentrations of Ca2+ and/or Mg2+ and induced with either FMLP or PMA were assessed. To account for nonspecific leukocyte-substrata interactions the OD's of iodoacetamide-inhibited adherent cell systems were subtracted from the OD values of adherent cells of noninhibited systems. Values presented were derived from OD's of iodoacetamide-inhibitable leukocyte binding. PMA was a much more potent inducer of leukocyte adherence than was FMLP, stimulating all available neutrophils and monocytes to adhere. In contrast, FMLP induced adherence by roughly 1/4 of the available neutrophils and few, if any, monocytes. Roughly the same binding pattern was noted whether surfaces were coated with albumin, fibrinogen, fibronectin, gelatin or serum. EDTA but not EGTA significantly suppressed leukocyte binding suggesting Mg2+ was more involved in binding than was Ca2+. Little leukocyte adherence to a substrata occurred in the absence of divalent cations, while enrichment of the medium with Mg2+ was more influential on cell binding than was enrichment with Ca2+. Interestingly, doxycycline, a member of the tetracycline family of drugs which has been reported to inhibit Mg(2+)-dependent neutrophil functions, had a slight inhibitory effect on neutrophil adherence at low drug concentrations, while it enhanced binding at higher doxycycline concentrations. In contrast, the tetracycline inhibited monocyte adherence in a dose-related manner.
白细胞黏附是宿主防御的关键事件，据报道其依赖于二价阳离子。为了测试白细胞结合受Ca2+还是Mg2+可用性的影响更大，评估了在含有不同浓度Ca2+和/或Mg2+的培养基中，用FMLP或PMA诱导的中性粒细胞和单核白细胞对涂有不同蛋白质的表面的黏附情况。为了考虑非特异性白细胞 - 底物相互作用，将碘乙酰胺抑制的黏附细胞系统的光密度值从未抑制系统的黏附细胞光密度值中减去。给出的值来自碘乙酰胺可抑制的白细胞结合的光密度值。PMA是比FMLP更强的白细胞黏附诱导剂，可刺激所有可用的中性粒细胞和单核细胞黏附。相比之下，FMLP诱导约1/4的可用中性粒细胞黏附，很少有单核细胞（如果有的话）黏附。无论表面涂有白蛋白、纤维蛋白原、纤连蛋白、明胶还是血清，都观察到大致相同的结合模式。EDTA而非EGTA显著抑制白细胞结合，表明Mg2+比Ca2+更多地参与结合。在没有二价阳离子的情况下，白细胞对底物的黏附很少发生，而培养基中Mg2+的富集对细胞结合的影响比Ca2+的富集更大。有趣的是，强力霉素是四环素类药物的一种，据报道可抑制Mg(2+)依赖性中性粒细胞功能，在低药物浓度下对中性粒细胞黏附略有抑制作用，而在较高强力霉素浓度下则增强结合。相比之下，四环素以剂量相关的方式抑制单核细胞黏附。
