Pruett J H, Fisher W F, DeLoach J R
U.S. Livestock Insects Laboratory, U.S. Department of Agriculture, Kerrville, Texas 78029.
Vet Res Commun. 1987;11(4):305-23. doi: 10.1007/BF00346190.
The synthetic glucocorticoid, dexamethasone, has been used by investigators studying bovine immune mechanisms to either exacerbate infectious processes or stimulate stress-induced steroid-influenced immunosuppression. Considerable differences exist in the literature concerning the effect of dexamethasone on the bovine immune response. The purpose of our study was to clarify the reported effects of dexamethasone on bovine T-lymphocyte function. Therefore, we designed experiments to evaluate cellular and humoral aspects of the bovine immune response under the influence of dexamethasone. The experiments took into consideration the pharmacokinetics of dexamethasone and optimal and suboptimal doses of selected mitogens. The data suggest little variation in hematological parameters that occurred with the administration of dexamethasone. Leukocyte counts were slightly elevated at two observations, and this was believed to be the result of an increase in peripheral blood neutrophils. T-lymphocytes (erythrocyte rosetting) were not selectively depleted. However, suppression of T-lymphocyte function was noted, particularly in response to suboptimum doses of phytohaemagglutinin (PHA) and Concanaval in A (Con A). Antibody production to the T-dependent antigen, KLH, was suppressed in those animals receiving dexamethasone. These data suggest that the immunosuppressive effect of dexamethasone in the bovine is dependent upon the dose of dexamethasone administered, the pharmacological level of dexamethasone in vivo, physiological adaptation of the host, mitogen dose used in evaluation, and the time of evaluation post drug administration. The study points out the importance of considering these variables when interpreting the effects of dexamethasone on the bovine immune response.
合成糖皮质激素地塞米松已被研究牛免疫机制的研究人员用于加剧感染过程或刺激应激诱导的类固醇影响的免疫抑制。关于地塞米松对牛免疫反应的影响，文献中存在相当大的差异。我们研究的目的是阐明地塞米松对牛T淋巴细胞功能的报道影响。因此，我们设计了实验来评估地塞米松影响下牛免疫反应的细胞和体液方面。实验考虑了地塞米松的药代动力学以及选定有丝分裂原的最佳和次优剂量。数据表明，给予地塞米松后血液学参数变化不大。在两次观察中白细胞计数略有升高，这被认为是外周血中性粒细胞增加的结果。T淋巴细胞（红细胞花环形成）未被选择性消耗。然而，注意到T淋巴细胞功能受到抑制，特别是对次优剂量的植物血凝素（PHA）和刀豆蛋白A（Con A）的反应。在接受地塞米松的动物中，对T依赖性抗原钥孔戚血蓝蛋白（KLH）的抗体产生受到抑制。这些数据表明，地塞米松在牛体内的免疫抑制作用取决于地塞米松的给药剂量、体内地塞米松的药理水平、宿主的生理适应性、评估中使用的有丝分裂原剂量以及给药后评估的时间。该研究指出在解释地塞米松对牛免疫反应的影响时考虑这些变量的重要性。
