细胞和体液免疫抑制对大鼠异种肝移植急性排斥中一氧化氮及其合酶、同功酶的影响

The Effect of Cellullar and Humoral Immunosuppression on Nitric Oxide and Nitric Oxide Synthase and Its Isoenzyme in the Acute Rejection of Golden Hamsters to Rat Liver Xenografts

目的 :探讨一氧化氮、一氧化氮合酶 (NOS)及其同功酶在大鼠异种肝移植中的免疫学作用及其表达意义。方法 :本实验共分 5组 :Ⅰ组 (同基因组 ) ;Ⅱ组 (急性排斥组 ) ;Ⅲ组 (细胞免疫抑制组 ) ;Ⅳ组 (体液免疫抑制组 ) ;Ⅴ组 (双重免疫抑制组 ) ;应用血清学检测移植术后受体血清ALT、TNF α及NO代谢终产物 (NOx) ,应用NADPH黄递酶组化及免疫组化检测NO合酶及其同功酶 (iNOS ,cNOS)的表达。结果 :Ⅱ、Ⅳ组血清ALT ,TNF α及NOx均较Ⅰ、Ⅴ组明显升高 4～ 11倍 (P <0 .0 1) ,环孢素A(Ⅲ组 )能抑制细胞免疫及NO的合成与表达 ,但不能延长受体的生存期。Ⅱ、Ⅳ组NO合酶及其同功酶 (iNOS ,cNOS)在异种肝移植急性排斥时明显表达。结论 :肝细胞NO在低免疫反应状态下可能具有肝细胞保护作用 ,而在高免疫反应状态下iNOS的持续高表达可能是肝损伤的原因。

Objective: To evaluate the effect of cellullar and humoral immunosuppression on nitric oxide, nitric oxide synthase and its isoenzyme in acute rejection of golden hamsters to rat liver xenografts. Methods: There were five randomly divided groups (n=6～9): isografts (group Ⅰ), xenografts in acute rejection (group Ⅱ), xenografts using cyclosporine (group Ⅲ), xenografts using cyclophosphamide in combination with splenectomy (group Ⅳ), and xenografts using splenectomy, cyclophosphamide and cyclosporine (group Ⅴ). The levels of serum ALT, TNF α, and nitric oxide production (NOx) in recipients were examined. Expressions of type Ⅱ (iNOS) and type Ⅲ (cNOS) nitric oxide synthase (NOS), inducible NOS (iNOS) and constitutive NOS (cNOS) were observed by NADPH diaphorase histochemical and immunohistochemical staining. Results: The levels of serum ALT activity of serum TNF α and systemic levels of NO metabolite in group Ⅱ and Ⅳ were higher than those of group Ⅰ and Ⅴ (P<0.01). Cyclosporine in group Ⅲ can repress the cellular immune response, the synthesis of nitric oxide and the expression of NO synthase, but can not prolong the liver xenograft survival. The overexpression of NOS, iNOS and cNOS in liver xenograft rejection in group Ⅱ and Ⅳ was detected by NADPH diaphorase histochemical and immunohistechemical staining. Conclusion: Hepatocyte derived nitric oxide may be protective in the hyperesponsive state, but hepatic injury is likely to be triggered by the centrilobular iNOS expression in the superresponsive state.