Wałajtys-Rode E, Dabrowski A, Grubek-Jaworska H, Machnicka B, Droszcz W
Institute of Internal Medicine, Warsaw Medical School, Poland.
Int J Immunopharmacol. 1988;10(8):925-30. doi: 10.1016/0192-0561(88)90038-0.
Purified rat peritoneal mast cells were incubated for 20 h with or without dexamethasone (4 x 10(-6) M) and then passively sensitized with serum from Trichinella spiralis-infected rats. The release of histamine using various secretagogues (concanavalin A, crude antigen of T. spiralis and polymyxin B) was determined. Dexamethasone treatment markedly inhibited IgE-dependent release of histamine (from 33.9 +/- 5.0% to 12.4 +/- 5.1% and from 39.8 +/- 7.9% to 14.2 +/- 6.5% of total cellular histamine content, respectively) whereas histamine release stimulated by the nonimmunological stimulus, polymyxin B was unaffected by this steroid. This suggests that the effects of dexamethasone cannot be exclusively explained by inhibition of phospholipases. Specific binding of 3H-dexamethasone to purified mast cells displayed sigmoidal dependence on concentration which may be the result of either negative cooperativity or the presence of a different class of binding sites. Two saturation plateaux at 20-30 x 10(-9) M and 70-90 x 10(-9) M were observed. The equilibrium dissociation constant for the higher affinity binding sites was Kd1 = 1.9 x 10(-8) M and represented 25,290 sites/cell, whereas the apparent Kd2 for lower affinity sites amounted to 5.5 x 10(-8) M and represented about 120,000 sites/cell.
将纯化的大鼠腹膜肥大细胞与地塞米松（4×10⁻⁶ M）一起或不与地塞米松一起孵育20小时，然后用旋毛虫感染大鼠的血清进行被动致敏。测定使用各种促分泌剂（刀豆球蛋白A、旋毛虫粗抗原和多粘菌素B）时组胺的释放情况。地塞米松处理显著抑制了组胺的IgE依赖性释放（分别从总细胞组胺含量的33.9±5.0%降至12.4±5.1%，从39.8±7.9%降至14.2±6.5%），而由非免疫刺激剂多粘菌素B刺激的组胺释放不受这种类固醇的影响。这表明地塞米松的作用不能完全用抑制磷脂酶来解释。³H-地塞米松与纯化肥大细胞的特异性结合对浓度呈S形依赖性，这可能是负协同作用或存在不同类别的结合位点的结果。观察到在20 - 30×10⁻⁹ M和70 - 90×10⁻⁹ M处有两个饱和平台。高亲和力结合位点的平衡解离常数为Kd1 = 1.9×10⁻⁸ M，每个细胞有25290个位点，而低亲和力位点的表观Kd2为5.5×10⁻⁸ M，每个细胞约有120000个位点。
