The regulatory functions of Ly-49A, Ly-49D and Ly-49G2 on NK cells in the recognition and rejection of the alloantigen in vivo.

Ly-49A is an inhibitory receptor that binds H-2Dd and H-2Dk. The downregulation of Ly-49A is thought to mediate NK self tolerance in vivo. In this study, we analyzed the regulation of Ly-49A, D and G2 on NK cells in an in vivo rejection model. After injection with 1 x 10(8) B10.D2 spleen cells (SC) into B 10 mice, we found Ly-49A downregulated within 3 h on NK cells of B10 mice, whereas expressions of Ly-49D and G2 were augmented. To investigate effects of different expression patterns of Ly-49 receptors on NK cells, Ly-49A, D or G2-depleted B10 mice were inoculated with B10.D2 SC. NK cells from SC of Ly-49A-depleted and B10.D2 SC-injected B10 mice showed enhanced cytotoxicity to Dd-positive targets in vitro. Furthermore, reduced numbers of B10.D2 SC were observed in Ly-49A or G2-depleted B10 mice, whereas increased numbers of B10.D2 SC were observed in Ly-49D-depleted B10 mice after inoculation with B10.D2 SC in vivo. These findings indicated that the downregulation of Ly-49A and the augmentation of Ly-49D expression may mediate NK cells to recognize and kill Dd antigen efficiently. In conclusion, each Ly-49 isoform may play independent roles in the regulation of activation or inhibition on NK cells.     

The augmentation of lymphokine-activated killer cells induced by partial hepatectomy in mice

Spleen cells that are cultured with interleukin 2 for as short a time as 4 days develop the ability to lyse syngeneic natural killer-resistant tumor cells but not to lyse syngeneic lymphoblasts. When mice were subjected to partial hepatectomy (HEP), the spleen cells exhibited not only an augmentation of natural killer activity, but also an augmentation ofin vitro induction of lymphokine activated killer (LAK) cells. Furthermore, the LAK cells exhibited lytic activities against syngeneic lectin-induced lymphoblasts and regenerating liver cells. The sensitivity of regenerating liver cells to lysis by LAK cells was detected as early as one day after HEP, and continued until day 14. Analysis by cell depletion techniques using monoclonal antibodies and complement, as well as discontinuous gradient sedimentation, indicated that the LAK cells activated by HEP were Thy-1⁺, Lyt-2⁺, asialo GM1⁺ and Lyt-1⁻, lymphocytes with a low density. After the intravenous (i.v.) administration of anti-asialo GM1 before HEP, thein vitro induction of LAK cells was remarkably inhibited.     

输注Wnt3a基因修饰的骨髓间充质干细胞减轻小鼠急性移植物抗宿主病

目的 探讨联合输注经Wnt3a基因修饰的MSC减轻小鼠异基因骨髓移植(allo-BMT)后急性移植物抗宿主病(aGVHD)的作用及其可能机制.方法 以C57BL/6小鼠为供鼠,以Balb/c小鼠为受鼠,建立小鼠allo BMT模型.采用随机数字表法将受鼠分为4组:(1)移植对照组(A组):经受鼠尾静脉仅输注供鼠骨髓细胞5×106个;(2) aGVHD组(B组):经受鼠尾静脉输注供鼠脾细胞5×106个及骨髓细胞5×106个;(3)aGVHD+空载体组(C组):经受鼠尾静脉输注供鼠脾细胞5×106个、骨髓细胞5×106个及转染了空载体pAd-GFP的MSC 1×106个;(4)实验组(D组):经受鼠尾静脉输注供鼠脾细胞5×106个、骨髓细胞5×106个及经Wnt3a基因修饰的MSC1×106个.移植后监测各组受鼠的一般表现和存活情况,观察aGVHD的发生情况,检测受鼠脾脏中供者来源的T淋巴细胞数量变化及白细胞介素2(IL-2)和γ干扰素(IFN-γ)水平.结果 A组受鼠的存活时间均超过60d;B、C、D组受鼠的存活时间分别为(19.1±6.19)d、(32.6±19.6)d和(47.2±15.6)d,D组受鼠的存活时间较B组和C组明显延长(P＜0.05).移植后,B、C、D组受鼠的aGVHD评分分别为(8.0±0.41)分、(6.7±0.29)分和(4.0±1.0)分,D组受鼠的aGVHD评分较B组和C组明显降低(P＜0.05),且病理分级明显减轻.移植后3和5d时D组受鼠脾脏中供者T淋巴细胞的数量和增殖速度均较B组和C组明显降低(P＜0.05),并且移植后7、14、21、28 d时D组受鼠血清IL-2和IFN-γ水平均较B组和C组明显减少(P＜0.05).术后60d时,长期存活受鼠的骨髓细胞中H-2Kb细胞的嵌合率均在95％～100％.结论 联合输注经Wnt3a基因修饰的MSC可更有效的减轻小鼠allo-BMT后的aGVHD,这可能与Wnt3a的过表达激活了MSC的Wnt/β-catenin信号通路,从而抑制供者T淋巴细胞的早期激活和扩增及抑制IL-2和IFN-γ的表达有关.     

In vivo depletion of NKR-P1 positive cells in the recipient prior to small bowel transplantation enhances graft-versus-host disease (GvHD) in the rat

Abstract  Recent evidence for major histocompatibility complex (MHC) class I antigen-directed recognition mechanisms of natural killer cells (NKs) have revived interests in investigating non-adaptive immune responses in the framework of solid organ transplantation. A semi-allogeneic rat model of heterotopic small bowel transplantation (HSBTx) from male DA parental to male F1 hybrid rats (DA X LEW) was established to investigate the role of host NKs to attenuate graft-versus-host (GvH)-mediated immu-nosuppression and tissue injury. By use of anti-NKR-P1 monoclonal antibody (mAb) 3.2.3, host NKs were depleted effectively in vivo after triple intraperitoneal injection prior to HSBTx. In contrast to non-depleted animals, an initial lack of NK activity in F1 hosts significantly decreased the mean survival ( P < 0.01) and substantially enhanced graft-versus-host disease (GvHD)-related damage to lymphoid and non-lym-phoid target organs. These findings emphasize the important immuno-regulatory role of host NKs during the early onset of GvHD.     

大鼠诱发肝癌模型中脾内转染IL-2和IL-12基因激活NK细胞

目的研究大鼠诱发肝癌模型中脾内直接注射携带白介素2（IL-2）和（或）白介素12（IL-12）基因的逆转录病毒包装细胞株对血IL-2和IL-12,以及NK细胞活性的影响.方法大鼠随即分为生理盐水对照组、空载体对照组、IL-12基因治疗组、IL-2基因治疗组及IL-2/IL-12联合基因治疗组.构建携带IL-2和（或）IL-12基因的逆转录病毒载体.口服二乙基亚硝胺诱癌后,含IL-2和（或）IL-12基因的包装细胞转染脾细胞.比较大鼠血IL-2和IL-12浓度、NK细胞活性、病理变化和毒性反应.结果IL基因治疗后血IL-2和IL-12明显增加.联合基因组同时表达IL-2和IL-12,总水平高于单基因治疗组.病理示治疗后肝癌组织中淋巴细胞浸润明显增多.IL治疗组NK细胞活性较对照组显著增高（P＜0.01）.联合基因组较IL单基因增高（P＜0.05）.治疗后3 d血清IL达高峰,以后逐步下降.结论脾内直接注射携带IL-2和（或）IL-12基因的逆转录包装细胞株可明显增强NK细胞活性,IL联合基因治疗优于IL单基因.