苯并(a)芘对金属硫蛋白基因敲除小鼠免疫功能的抑制

目的:观察苯并(a)芘benzo(a)pyrene, B(a)P] 对金属硫蛋白(metallothionei n, MT)基因敲除的转基因小鼠MT(-/-)]免疫功能的影响 .方法:选用MT(-/-)小鼠和野生型小鼠MT(+/+)]进行对照,50 mg·kg -1体重的B(a)P 一次腹腔注射染毒后,检测动物对绵羊红细胞(sheep red blood ce lls, SRBC)的体液和细胞免疫功能变化.体液免疫指标为抗体形成细胞(plaque formation cells, PFC)数量.细胞免疫功能指标为迟发型变态反应(delayed-type hypersensitivi ty, DTH)的动物足跖厚度变化 .结果:MT(-/-)小鼠的脾脏重量在S RBC刺激后有明显增加,但在B(a)P染毒后被抑制.B(a)P染毒使MT(-/-)小鼠脾脏的的PFC 数明显减少,PFC抑制率达40.4%;而MT(+/+)小鼠没有观察到上述改变.B(a)P染毒对MT (-/-) 小鼠和MT(+/+)小鼠的细胞免疫反应的DTH未见明显影响.MT(-/-)小鼠和MT(+/+)小鼠的胸腺重量在B(a)P 染毒后都有减轻.结论:MT(-/-)小鼠的体液免疫功能更易被B(a)P抑制.提示MT具有保护小鼠不受B(a)P体液免疫损伤的功能.

Induc tion of immunosuppression by benzo(a)pyrene in metalloth ionein knocked-out mi ce

Objective: To study the immonotoxicity induced by Benzo(a)pyrene in metallothionein gene knocked mice and compare with that in wild type mice . Methods: Female mice were treated with B(a)P (50 mg/kg body weight, i. p.) and immunized with sheep red blood cells (SRBC) i. v. on the following day and rechallenged by s.c. injection of SRBC into the mouse footpad on day 4 post immunization. Humoral immune function was assessed by spleen IgM antibody plaque formation cells (PFC) to SRBC. Delayed type hypersensitivity (DTH) was measured by footpad swelling response. Results: In MT (-/-) mice, both the spleen weight and PFC per spleen were decreased after B(a)P treatment compared with those in SBRC group, while there were no changes in MT(+/+) mice. The weights of thymus were decreased by B(a)P in both kinds of mice. DTH was not altered by B(a)P in both kinds of mice. Conclusion: MT (-/-) mice are more susceptible to B(a)P induced suppression of humoral immunity. These results indicate that MT plays a role in protecting the mice of against B(a)P induced immunotoxicity.