本文旨在研究不同剂量地塞米松及不同免疫调节剂对鸡免疫功能的作用，以确定临床上地塞米松的用量上限及寻找一种效果较好的免疫调节剂。将10日龄鸡随机分为对照组、0.1、0.5、1.5 mg/kg·BW地塞米松组，通过饮水添加地塞米松，检测多种免疫指标。结果表明地塞米松可影响正常鸡的免疫功能，0.1、0.5、1.5 mg/kg·BW地塞米松均可极显著抑制鸡外周血T淋巴细胞增殖（P＜0.01），但对B淋巴细胞无明显影响；0.5、1.5 mg/kg·BW地塞米松可极显著抑制鸡白细胞介素-2的活性（P＜0.01）；0.5、1.5 mg/kg·BW地塞米松组的新城疫抗体水平显著低于对照组（P＜0.05）；0.5、1.5 mg/kg·BW地塞米松组淋巴细胞比率显著低于对照组（P＜0.05）；地塞米松组的鸡总体重、免疫器官及法氏囊指数显著低于对照组。将10日龄鸡随机分为4组，分别为对照组、干扰素组、干扰肽组和胸腺肽组，试验前5 d所有组饮水中均添加0.5 mg/kg·BW地塞米松，5 d后各组分别在饮水中添加相应的免疫调节剂，试验结束后检测免疫指标。结果表明：干扰素、胸腺肽组的T淋巴细胞转化率极显著高于对照组（P＜0.01）；胸腺肽组的新城疫抗体水平显著高于对照组（P＜0.05），白细胞数、淋巴细胞数极显著高于对照组（P＜0.01），总体重显著高于对照组（P＜0.05）；干扰素组的脾脏指数显著高于对照组（P＜0.05）。试验结果说明当地塞米松的用量超过0.5 mg/kg·BW可抑制鸡的免疫功能，而干扰素和胸腺肽对鸡群有免疫调节作用，可在一定程度上提高鸡群的免疫力。%The present study focused on effect of different doses of dexamethasone on the immune functions of chickens. Ten-day-old chickens were orally administered with 0.1, 0.5 or 1.5 mg/kg·BW dexamethasone, respectively, and a number of immune indexes were tested. The result showed that dexamethasone affected normal immune functions in chickens. Dexamethasone suppressed proliferative capacity of T lymphocytes in chicken peripheral blood but had no obvious effect on B lymphocytes. In addition, dexamethasone inhibited activity of interleukin-2 in chickens. The Newcastle disease antibody level was low in dexamethasone treated chickens. The Lymphocyte ratios and chickens’ overall weights, immune organ indexes and fabricius of bursa in dexamethasone treated chickens were lower than those of non-treated control group. These results showed that 0.5, 1.5 mg/kg·BW dexamethasone inhibited immune functions of chickens. In the next study, ten-day-old chickens were given drinking water containing dexamethasone at 0.5 mg/kg·BW for consecutive 5 days and then interferon, interferon-like peptide or thymus peptide were added to the water. T lymphocyte conversion rates in chickens receiving thymus peptide and interferon were significantly higher than that of non-treatment controls, indicating their immunoregulatory role.
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