Rensberger K L, Hoganson D A, Mehvar R
Department of Biology, Drake University, Des Moines, IA 50311, USA.
Int J Pharm. 2000 Oct 10;207(1-2):71-6. doi: 10.1016/s0378-5173(00)00544-5.
The in vitro immunosuppressive activity of a conjugate of methylprednisolone (MP) with dextran 70 kDa (DEX-MPS) was tested using the lymphocyte proliferation assay after stimulation of lymphocytes with concanavalin A (Con-A). Blood and spleen lymphocytes, isolated from drug-free male Sprague-Dawley rats, were used in the assay. First, the optimum concentration of Con-A for stimulation of lymphocytes was determined. The inhibition of the lymphocyte proliferation was then tested in the presence of 0.25,0.5, 1.0,2.5,5.0,10,20, and 50 nM concentrations (MP equivalent) of DEX-MPS or free MP. The maximum stimulation of lymphocytes with Con-A was observed at mitogen concentrations of 2.5 and 10 microg/ml for the spleen and blood lymphocytes, respectively. For free MP, sigmoidal relationships were observed between the effect (% inhibition of lymphocyte proliferation) and the logarithm of MP concentration. Additionally, the maximum inhibitory effect (I(max)) and MP concentration producing half of I(max) (IC(50)) were, respectively, 98% and 1.38 nM for the blood and 86% and 3.1 nM for the spleen lymphocytes. For MP conjugated to dextran, the response-log concentration curves were substantially shifted to the right with IC(50) values of 40 and 52 nM for the blood and spleen lymphocytes, respectively. It is concluded that compared with free MP, the steroid attached to dextran has minimal immunosuppressive activity. Therefore, to be effective in vivo, DEX-MPS should release MP in the body.
使用伴刀豆球蛋白A（Con-A）刺激淋巴细胞后，通过淋巴细胞增殖试验检测甲基强的松龙（MP）与70 kDa葡聚糖（DEX-MPS）缀合物的体外免疫抑制活性。从无药物的雄性Sprague-Dawley大鼠分离的血液和脾脏淋巴细胞用于该试验。首先，确定刺激淋巴细胞的Con-A的最佳浓度。然后在存在0.25、0.5、1.0、2.5、5.0、10、20和50 nM浓度（MP当量）的DEX-MPS或游离MP的情况下测试淋巴细胞增殖的抑制作用。对于脾脏和血液淋巴细胞，分别在2.5和10 μg/ml的促细胞分裂剂浓度下观察到Con-A对淋巴细胞的最大刺激。对于游离MP，在效应（淋巴细胞增殖抑制百分比）与MP浓度的对数之间观察到S形关系。此外，血液淋巴细胞的最大抑制作用（I(max)）和产生I(max)一半的MP浓度（IC(50)）分别为98%和1.38 nM，脾脏淋巴细胞分别为86%和3.1 nM。对于与葡聚糖缀合的MP，响应-对数浓度曲线显著向右移动，血液和脾脏淋巴细胞的IC(50)值分别为40和52 nM。得出的结论是，与游离MP相比，附着在葡聚糖上的类固醇具有最小的免疫抑制活性。因此，为了在体内有效，DEX-MPS应在体内释放MP。
