目的 探讨弓形虫感染小鼠氧化应激状态对免疫功能的影响和香菇多糖(LNT)对小鼠脑保护作用及可能的作用机制.方法 流式细胞术检测各组实验小鼠脑组织中活性氧自由基(ROS)及脾脏中Th1/Th2细胞亚群.结果 感染后第4天,对照组小鼠出现死亡,于感染后第8天小鼠全部死亡;而LNT组小鼠感染后第6天才出现死亡,感染后第10天小鼠全部死亡;pre-6d LTN组小鼠在感染后第8天开始出现死亡,存活率为20％.对照组小鼠脾脏中ROS水平于感染后8d出现有意义升高(P＜0.01);pre-LNT组和LNT组小鼠在感染后4和8d脾脏中ROS水平均出现有意义升高(P＜0.05,P＜0.01).各组小鼠脾脏中CD4+IFN-γ+(Th1)细胞数均于感染后4和8d均出现有意义升高(P＜0.01);但与同天对照组小鼠相比,pre-LNT组和LNT组第4天和8天脾脏中Th1细胞水平均显著下降(P＜0.05,P＜0.01).对照组小鼠和LNT组小鼠脾脏中CD4+ IL-4+ (Th2)细胞数无明显变化(P＞0.05);pre-LNT组小鼠在感染后4和8dTh2细胞水平均出现有意义升高(P＜0.05);但与同天正常感染组小鼠相比,pre-LNT组第8天脾脏中Th2细胞水平均显著增加(P＜0.05).结论 LNT能有效控制急性弓形虫感染早期ROS的产生及Th1细胞数量,对于感染性疾病急性进展期控制严重的炎症反应极其有效.

Objective To examine the immune mechanism by which lentinan(LTN)inhibits acute infection with Toxoplasma gondii in mice through balancing of the Th1/Th2 immune response and maintaining that balance. Methods Mice were intraperitoneally injected with T.gondii tachyzoites and their survival rate was calculated when pre-treated with LTN and when treated with LTN post-infection.IFN-γand IL-4 are key cytokines of Th1 and Th2 cells,respectively.Levels of IFN-γand IL-4 in spleen cell suspensions were determined using ELISA.The immunoglobulins IgG1 and IgG2a are associated with Th1 and Th2 response.Levels of these immunoglobulins in serum were also determined. Results Lentinan markedly increased the survival rate for mice treated with LTN post-infection and mice pre-treated with LTN in comparison to the control group.Mice treated with LTN post-infection all died on day 10post-infection,but mice pre-treated with LTN had a survival rate of 18.4% on day 13post-infection.On day 3 post-infection,mice pre-treated with LTN and mice treated with LTN post-infection had developed a Th1 immune response.Mice pre-treated with LTN had an IFN-γlevel of 186.28pg/ml while mice treated with LTN post-infection had an IFN-γlevel of 117.07pg/ml.There were significant differences in IFN-γlevels in comparison to the control group(P0.01).Mice pre-treated with LTN had an IgG2a level of 0.332(A490)while mice treated with LTN post-infection had an IgG2a level of 0.320(A490)(P0.01),and IgG2a levels peaked on day 7.Mice pre-treated with LTN and mice treated with LTN post-infection began to develop a Th2immune response.Mice pre-treated with LTN had an IL-4 level of 121.28pg/ml while mice treated with LTN post-infection had an IL-4level of 94.47pg/ml(P0.01).Mice pre-treated with LTN had an IgG1 level of 0.382(A490)and while mice treated with LTN post-infection had an IgG1level of 0.354(A490)(P0.05). Conclusion LNT helped mice to develop a Th1/Th2 immune response.This balance shifted at the appropriate time from Th1to Th2,parasites were eliminated,and the balance between the Th1 and Th2 response was maintained.This avoided an excessive immune response as would induce immunopathological damage.

[Objective]To observe the inhibition effec of Lentinan on acute infection of Toxoplasma gondii in mice.[Methods]The levels of IFN-γ and NO in the suspension of spleen cell were detected by ELISA and Griess,the survival rate of mouse that were intraperitoneally injected with Toxoplasma gondii achyzoites was observed.[Results]The lentinan could increase the survival rate of Toxoplasma gondii-infectedmice.The negative group mice which were infected with Toxoplasma gondii achyzoites began to die after 3 days,and died out after 8 days.At the same time,the mice of the positive group and the pre-6d LTN group began to die after 5 days,after 9 days the survival rate of the above two groups was 6.67% and 20.00% respectively.The LTN group mice started to die after 4 days,died out after 9 days.The level of IFN-γ increased significantly in pre-6 d LTN group and LTN group compared with the negative group.The level reached the peak after 6 days,the concentration was 428.77(pg/ml) and 314.80(pg/ml)respectively,but the level of the negative group was only 74.55(pg/ml).There was significant difference between experimental and control groups(P<0.01).At the same time,the contents of NO varied with the level of IFN-γ change,and after 6 days reached the peak,the concentration was 54.17(μmol/L)and 32.65(μmol/L)respectively;the content of the negative group was 8.22(μmol/L).The differences between experimental and control groups were significant(P<0.01).[Conclusion]The lentinan can effectively resist the acute infection of Toxoplasma gondii in mice.

多年来,章丘市认真贯彻执行<传染病防治法>及其配套法规,坚持"预防为主"的卫生工作方针,全面落实各项综合防治措施,疾病预防控制工作取得了明显成效,为保障全市人民健康,促进经济发展做出了积极贡献.但我们也注意到工作中存在的问题和不足,并着手探讨解决问题的对策.