A1 adenosine receptor activation inhibits inflammation, necrosis, and apoptosis after renal ischemia-reperfusion injury in mice

It was previously demonstrated that preischemic A(1) adenosine receptor (AR) activation protects renal function after ischemia-reperfusion (IR) injury in rats. The role of the A(1) AR in modulating inflammation, necrosis, and apoptosis in the kidney after IR renal injury was further characterized. C57BL/6 mice were subjected to 30 min of renal ischemia, with or without pretreatment with 1,3-dipropyl-8-cyclopentylxanthine or 2- chlorocyclopentyladenosine (selective A(1) AR antagonist and agonist, respectively). Plasma creatinine levels and renal inflammation, necrosis, and apoptosis were compared 24 h after renal injury. C57BL/6 mice that had been pretreated with the A(1) AR agonist demonstrated significantly improved renal function and reduced expression of inflammatory markers, necrosis, and apoptosis 24 h after IR injury. In contrast, C57BL/6 mice that had been pretreated with the A(1) AR antagonist demonstrated significantly worsened renal function and increased expression of inflammatory markers, necrosis, and apoptosis. In conclusion, it was demonstrated that endogenous and exogenous preischemic activation of the A(1) AR protects against IR injury in vivo, through mechanisms that reduce inflammation, necrosis, and apoptosis.     

脑缺血预处理对小鼠脑缺血再灌注损伤的保护作用

目的 研究脑缺血预处理对脑缺血再灌注损伤的保护作用。方法 C57BL/6 小鼠分4组,无缺血对照组行假手术,预处理对照组夹闭双侧颈总动脉6min,缺血组夹闭双侧颈总动脉18min,预处理组经6min缺血预处理后48h再行18min脑缺血。末次缺血后3d使用TUNEL原位标记法检测海马区神经原的DNA断片化改变,末次缺血后7d,用甲酚紫染色及微小管相关蛋白2免疫组化染色法观察海马区神经元损伤。结果 6min脑缺血未导致海马神经元缺失,18min脑缺血造成双侧海马神经元大量缺失,6min预处理明显减轻18min脑缺血所造成的神经元损伤及凋亡。结论 脑缺血预处理对脑缺血再灌注损伤有保护作用,此预处理模型为在基因水平研究脑缺血预处理保护作用的分子机制提供了一种新的手段。     

Inhibition of Kupffer cells reduced CXC chemokine production and liver injury

BACKGROUND: Cytokine production is a critical component of ischemia/reperfusion (IR) injury. In the liver, Kupffer cells produce cytokines and chemokines (i.e., cytokines with chemoattractant properties) that are important mediators in neutrophil recruitment and subsequent hepatocellular injury. Therefore, the role of Kupffer cells in chemokine production in hepatic IR injury was investigated. METHODS: Adult male C57BL/6 mice underwent 90 min of partial hepatic ischemia followed by various reperfusion times (i.e., 0, 1.5, 3, and 6 h). Gadolinium chloride (GC), which inhibits Kupffer cell activity, was administered to mice 48 and 24 h prior to ischemia. The control group received a corresponding volume of normal saline. Plasma levels of the cytokine macrophage inflammatory protein-2 (MIP-2), KC, and tumor necrosis factor (TNF)-alpha and liver mRNA were measured. Liver injury was assessed by plasma level of alanine transaminase (ALT) and histopathology. RESULTS: A reperfusion time-dependent liver injury occurred as indicated by increased levels of plasma ALT and histopathology. The injury was associated with increased plasma TNF-alpha, MIP-2, and KC and their hepatic mRNA expression and neutrophil infiltration into ischemic lobes of the liver. GC treatment significantly reduced the number of Kupffer cells as determined by the immunostained liver tissue sections. The extent of liver injury significantly decreased in GC-treated mice that were associated with decreased levels of plasma ALT, TNF-alpha, MIP-2, and KC and neutrophil infiltration. CONCLUSIONS: This study suggests that Kupffer cells are major contributors to cytokine production in hepatic IR and their modulation may serve as a potential target for therapeutic intervention.     

Mechanism of miR-21 in delayed ischemia preconditioning and its protection against subsequent ischemia reperfusion injury in kidney

Objective To investigate the molecular mechanism of protection of ischemia preconditioning on renal ischemia reperfusion injury. Methods Male C57/BL6N mice were randomly divided into two groups: in IR group, 35 min ischemia was induced by occlusion of both renal pedicles followed by 24 h perfusion (I/R). 15 min ischemia was induced 4 days before I/R in IPC group. Blood sample and kidney were collected in IR and IPC group after 24 h perfusion. Serum creatinine (Scr) and histological changes were used to evaluate the renal injury. PHD2 and HIF-1α were evaluated by Western blotting, miR-21 expression was confirmed by real-time PCR. In vitro, hypoxic model was established by 1% O2 in HK-2 cells. Knockdown of miR-21 in hypoxic model was perfermed by locked nucleic acid modified-anti-miR-21 transfection. The levels of miR-21, HIF-1α and PHD2 mRNA were confirmed by real-time PCR. The levels of HIF-1α and PHD2 proteins were tested by Western blotting. Results In vivo, Compared with IR group, the renal function and histological changes were improved in IPC group (P＜0.01). Compared with IR group, the expression of miR-21(P＜0.01) and HIF-1α (P＜0.05) were increased in IPC group, while PHD2 was reduced (P＜0.01). In vitro, hypoxia reduced miR-21. The inhibition of miR-21 could increased the expression of PHD2 (P＜0.05). Conclusions Ischemia preconditioning may exert protection against renal ischemia reperfusion injury by inhibiting PHD2.     

Antigen-specific T-regulatory cells can extend skin graft survival time in mice

This study investigated the effects of donor antigen-specific CD4(+)CD25(+) T-regulatory cells (Tregs) on skin allografts in mice. An allogeneic skin transplant model was established using donor C57BL/6 or DBA and recipient BALB/c mice. Recipients were divided into 4 groups: control group without intervention (CON; C57BL/6 to BALB/c), rapamycin gavage group (RAP; C57BL/6 to BALB/c), CD4(+)CD25(+) Tregs-treated group (TRE; C57BL/6 to BALB/c), in which recipients received transfusions of CD4(+)CD25(+) Tregs stimulated with C57BL/6-derived immature dendritic cells, and the third-party donor group (DBA; DBA to BALB/c) in which recipients received transfusions of BALB/c CD4(+)CD25(+) Tregs stimulated with C57BL/6-derived immature dendritic cells. Mean (SD) survival time of the skin allografts in the TRE group was 17.0 (3.4) days, significantly longer than in the other groups: CON, 6.9 (1.9) days; RAP, 10.3 (3.0) days; and DBA, 10.8 (3.6) days. The TRE group demonstrated a significantly greater expression of transforming growth factor-β and interleukin (IL)-10. Donor antigen-specific CD4(+)CD25(+) Tregs effectively extend skin allograft survival in mice.     

Earlier renal fibrosis aggravates acute kidney injury induced by ischemia reperfusion in mice

Objective To investigate the influence of earlier renal fibrosis on ischemia and reperfusion induced acute kidney injury. Methods Male C57BL/6 mice at eight to twelve weeks old age were divided into 4 groups randomly: (1)Sham (n=3); (2)Unilateral ureter obstruction (UUO, n=6): UUO for 3 days (UUO3d, n=3) and UUO for 5 days (UUO5d, n=3)；(3)Ischemia and reperfusion (IR, n=7): bilateral kidney ischemia for 40 minutes followed by 24 hours of reperfusion; (4)UUO for 3 days plus IR (UUO3d+IR, n=6): bilateral kidney ischemia after UUO 2 days for 40 minutes followed by 24 hours of reperfusion, and the real time for UUO was 3 days. Pathologic analysis for acute or chronic injury was performed on paraffin embedded kidney sections with hematoxylin and eosin (HE) or Masson staining. Apoptosis was detected by immunohistochemistry(IHC) and Western blotting with anti-caspase-3 antibody, and proliferation was observed by IHC with anti-ki67 antibody. Results On kidney sections with HE or Masson staining, it showed that the chronic kidney lesions and fibrosis got more severe as time of UUO prolonged from 3 days to 5 days; the area of matrix deposition increased in UUO5d and UUO3d mice significantly compared to Sham mice (P＜0.05) and was smaller in UUO3d mice compared with UUO5d mice obviously (P＜0.05). Acute kidney injury could be observed in UUO3d+IR mice, such as massive inflammatory cells infiltration, tubules dilation, brush border disappearance, tubular epithelial cells vacuolar degeneration, necrosis, casting formation, coexisting with chronic lesions: thinner cortex, broadened interstitial space, and increased blue stained matrix. Acute kidney injury score in UUO3d+IR mice was higher than that in IR mice significantly (P＜0.05), and serum creatinine level increased significantly in UUO3d+IR mice compared to Sham mice (P＜0.05). Caspase-3 expression increased and ki67 positive tubular cells decreased in UUO3d+IR mice than those in IR mice obviously (P＜0.05). Conclusion Earlier renal fibrosis aggravates acute kidney injury induced by ischemia reperfusion in mice through increasing apoptosis and decreasing proliferation of tubular epithelial cells.     

骨髓间充质干细胞干预对急性肾损伤鼠肾脏中细胞因子的影响

目的：建立缺血再灌注（I/R）诱导的急性肾损伤小鼠模型,探讨外源性地给予骨髓间充质干细胞（MSCs）干预对模型小鼠肾损伤微环境中细胞因子水平的影响,并探讨其在肾损害修复中的作用。方法：采用Percoll密度梯度离心法分离出C57BL/6小鼠的骨髓间充质干细胞（mMSCs）。雄性C57BL/6小鼠45只,分为正常对照组（15只）、I/R组（15只、夹闭双侧肾蒂30min开放）、I/R＋mMSCs组（15只、夹闭双侧肾蒂30min开放的同时尾静脉注射mMSCs）。于建模后1d、2d、3d、7d、14d分别处死部分小鼠（每次每组均处死3只）,留取动脉血及肾组织,检测血尿素氮（BUN）及肌酐（Scr）水平,制作肾组织切片行HE染色,观察肾组织病理变化,行肾小管坏死程度评分（ATN评分）。ELISA法检测肾组织匀浆肿瘤坏死因子-α（TNF-α）、白细胞介素-1β（IL-1β）、单核细胞趋化蛋白-1（MCP-1）、白细胞介素-10（IL-10）、肝细胞生长因子（HGF）、骨形态发生蛋白-7（BMP-7）的水平。结果：I/R组小鼠的BUN及Scr均显著高于正常对照组,肾小管损伤严重;而I/R＋mMSCs组小鼠的BUN及Scr水平较I/R组为低,以术后第7天差异最为显著（P〈0.01）,肾小管损伤病理明显减轻,ATN评分也有着显著降低。ELISA结果显示单纯I/R组各时间点肾组织匀浆中TNF-α、IL-1β、MCP-1的水平显著升高（P〈0.01或P〈0.05）,而IL-10、HGF、BMP-7的水平却有着显著降低（P〈0.01或P〈0.05）。但同时给予MSCs干预的I/R小鼠肾组织匀浆中前述细胞因子的水平却向着相反方向改变。结论：MSCs对I/R肾组织中细胞因子的分泌具有调控作用,而这些调控了的细胞因子进而可通过旁分泌作用发挥促进肾损害的修复作用。     

静脉注射含饱和氢气生理盐水减轻小鼠肾脏缺血再灌注损伤

目的 研究静脉注射含饱和氢气生理盐水对小鼠肾脏缺血再灌注(IR)损伤的保护作用及其机制.方法 健康、雄性的C57BL/6小鼠随机分为3组,每组10只.假手术组(SO组)小鼠仅接受中线开腹、双侧肾蒂游离及关腹操作;缺血再灌注组(IR组)小鼠用无损伤动脉夹同时钳夹双侧肾蒂,阻断45 min,制成肾脏IR损伤模型,并于肾脏缺血同时经尾静脉注射生理盐水,5 ml/kg;实验组小鼠制成肾脏IR损伤模型,并于肾脏缺血同时经尾静脉注射含饱和氢气生理盐水,5 ml/kg.各组小鼠于肾脏再灌注6 h时检测血清尿素氮(BUN)和肌酐(Scr);检测肾组织中丙二醛(MDA)和髓过氧化物酶(MPO)的含量;观察肾脏组织形态学变化并检测肾小管上皮细胞的凋亡情况;观察肾组织中巨噬细胞的浸润情况;检测各组小鼠肾组织中肿瘤坏死因子α(TNF-α)、白细胞介素6(IL-6)、IL-1β和IL-17 mRNA的水平.结果 实验组血清BUN和Scr水平明显低于IR组(P<0.05).实验组肾组织病理改变较IR组明显减轻,其肾小管损伤评分明显低于IR组(P<0.01),肾小管上皮细胞凋亡明显轻于IR组(P<0.05).实验组肾组织内MDA含量低于IR组(P<0.05).实验组小鼠肾组织内中性粒细胞和巨噬细胞的浸润较IR组减少(P<0.05).实验组TNF-α、IL-6、IL-1β和IL-17mRNA的水平均低于IR组(P<0.05).结论 静脉注射含饱和氢气生理盐水能够在一定程度上减轻肾脏IR损伤,其机制可能与抑制肾脏IR后炎症反应有关.     

Effects of Thy-1+ cell depletion on the capacity of donor lymphoid cells to induce tolerance across an entire MHC disparity in sublethally irradiated adult hosts

Thy-1+ cell depletion with anti-Thy-1.2 mAb and complement markedly reduced the capacity of C57BL/6J, H-2b bone marrow to establish mixed lymphoid chimerism and induce tolerance to C57BL/6J skin grafts across an entire MHC disparity in BALB/c, H-2d hosts conditioned with sublethal, fractionated 7.5 Gy total-body irradiation. In this model tolerance can be transferred to secondary irradiated BALB/c hosts only by cells of C57BL/6J donor, not host, genotype isolated from the spleens of tolerant hosts. Thy-1+ cell depletion abolished the capacity of C57BL/6J donor cells from tolerant BALB/c host spleens to transfer tolerance. The capacity of semiallogeneic BALB/c x C57BL/6J F1, H-2d/b donor BM and spleen cells to induce chimerism and tolerance to C57BL/6J skin grafts in BALB/c parental hosts was also reduced by Thy-1+ cell depletion. Thus the requirement for donor Thy-1+ cells cannot be explained simply on the basis of alloaggression. It is unlikely that the requisite Thy-1+ cells are nonspecific suppressor cells: Thy-1+ cell depletion had no effect on the slight but significant prolongation of third-party C3H/HeJ, H-2k skin grafts in irradiated BALB/c hosts injected with allogeneic C57BL/6J or semiallogeneic BALB/c x C57BL/6J F1 BM compared to irradiated controls injected with medium only. Furthermore, injections of semiallogeneic F1 spleen cells had no significant effect on the survival of the third-party grafts, although these cells were fully capable of inducing tolerance, and their capacity to induce tolerance was significantly reduced by Thy-1+ cell depletion. The requirement for a specific population of lymphoid cells, i.e. Thy-1+, remains unexplained but suggests that donor cells might play a role in the induction or maintenance of tolerance in this model other than merely providing a circulating source of donor antigens.     

Toll-like receptor 4 mediates ischemia/reperfusion injury of the heart

BACKGROUND: Restoration of blood flow to the ischemic heart may paradoxically exacerbate tissue injury (ischemia/reperfusion injury). Toll-like receptor 4, expressed on several cell types, including cardiomyocytes, is a mediator of the host inflammatory response to infection. Because ischemia/reperfusion injury is characterized by an acute inflammatory reaction, we investigated toll-like receptor 4 activation in a murine model of regional myocardial ischemia/reperfusion injury. We used C3H/HeJ mice, which express a nonfunctional toll-like receptor 4, to assess the pertinence of this receptor to tissue injury after reperfusion of ischemic myocardium. METHODS: Wild-type mice (C3H/HeN) or toll-like receptor 4 mutant mice (C3H/HeJ) were subjected to 60 minutes of regional myocardial ischemia followed by 2 hours of reperfusion. At the end of reperfusion, the area at risk and the myocardial infarct size were measured as the end point of myocardial ischemia/reperfusion injury. Myocardial mitogen-activated protein kinase activation was measured by Western blotting, and nuclear translocation of nuclear factor-kappaB and activator protein-1 was determined by electrophoretic mobility shift assay. Ischemia/reperfusion-injured myocardium was also assessed by ribonuclease protection assay for expression of inflammatory mediators (tumor necrosis factor-alpha, interleukin-1beta, monocyte chemotactic factor-1, and interleukin-6). RESULTS: The area at risk was similar for all groups after myocardial ischemia/reperfusion injury. There was a 40% reduction in infarct size (as a percentage of the area at risk) in C3H/HeJ mice compared with C3H/HeN mice (P =.001). Within the myocardium, significant activation of c-Jun N-terminal kinase, p38, and extracellular signal-regulated kinase was observed in both strains after ischemia and during reperfusion as compared with an absence of mitogen-activated protein kinase activation during sham operations; however, c-Jun N-terminal kinase activity, but not p38 or extracellular signal-regulated kinase activity, was significantly reduced in C3H/HeJ mice (P <.05). In both groups, nuclear factor-kappaB and activator protein-1 nuclear translocation occurred in the myocardium during myocardial ischemia/reperfusion injury, but, by densitometric analysis, nuclear translocation of nuclear factor-kappaB and activator protein-1 was significantly decreased in C3H/HeJ mice compared with C3H/HeN mice. Interleukin-1beta, monocyte chemotactic factor-1, and interleukin-6 were detectable in reperfused ischemic myocardium but were not detected in sham-operated myocardium; the expression of each of these mediators was significantly decreased in the myocardial tissue of C3H/HeJ mice when compared with expression in the control C3H/HeN mouse strain. CONCLUSIONS: Our data suggest that toll-like receptor 4 may mediate, at least in part, myocardial ischemia/reperfusion injury. Inhibition of toll-like receptor 4 activation may be a potential therapeutic target to attenuate ischemia/reperfusion-induced tissue damage in the clinical setting.     

Reperfusion injury to skeletal muscle affects primarily type II muscle fibers

INTRODUCTION: The injury caused by reperfusion of ischemic skeletal muscle is mediated by the membrane attack complex of complement (C) . This C activation results from local classical pathway activation after deposition of IgM in injured muscle, an event analogous to C deposition in the mucosa of the gut during reperfusion . Our past analysis has indicated that the injury is not uniform even within a single microscopic section. This study was performed to elucidate the exact site of IgM and C deposition on muscle injured by ischemia and reperfusion. MATERIALS AND METHODS: C57Bl/6 mice were subjected to 2 h of tourniquet-induced hindlimb ischemia followed by reperfusion for 0-6 h. Three muscle groups (vastus, gastrocnemius, and soleus) of varying fast-myosin content were compared for muscle fiber damage and C deposition. Adjacent paraffin-embedded cross-sections were immunostained to correlate C3 deposition with muscle fiber type as defined by monoclonal antibodies. RESULTS: Muscle injury after ischemia and reperfusion is not uniform and not all fibers in the same microscopic field are affected. Damaged fibers are also those to which IgM and C bind. Immunostaining for slow-twitch (Type 1) or fast-twitch (Type 2) fibers reveals that injury and C3 deposition is confined to Type 2 fibers with lower myosin content. A correlation of Type 2 fiber content and degree of muscle injury showed that the predominantly fast-twitch vastus muscle had the greatest number of damaged fibers per x10 field (28.2 +/- 12.4) when compared to the mixed fiber-type gastrocnemius muscle (20.5 +/- 5.3) and the mixed, but slow-twitch enriched soleus muscle (17.3 +/- 11.8). CONCLUSION: Complement activation and skeletal muscle reperfusion injury occurs predominantly on Type 2 fibers with low myosin content. This suggests that attempts to control the post-reperfusion inflammation will likely produce substantial muscle recovery. Furthermore, the basis of IgM deposition and complement activation may be revealed in the comparison of the two muscle fiber types.     

Th1/Th2 xenogenic antibody responses are associated with recipient dendritic cells

We characterized dendritic cells (DC) phenotypically and functionally between C57BL/6 (Th1-prone) and BALB/c (Th2-prone) mouse recipients in an in vivo sensitization model. Two strains of mice were presensitized with Lewis rat splenocytes as xenogeneic antigens. We found that BALB/c recipients mounted a significantly higher total IgG response to the xeno-antigens when compared with C57BL/6 recipients, 10 days after rat splenocyte infusion. A Th2-mediated antibody response with high ratio of IgG1/IgG2a was seen in the BALB/c recipients, while a Th1 antibody response with low ratio of IgG1/IgG2a was detected in C57BL/6 recipients. CD11c(+)DC isolated from C57BL/6 recipients possessed increased expression of CD8alpha(+) (DC-1 type). The administration of bone marrow derived-DC from IL-12 knockout mice into C57BL/6 recipients induced a shift of Th-mediated anti-xenogeneic antibody responses from Th1 to Th2 domain. Our findings suggest that DC could play an important role to regulate the balance of Th1/Th2 cytokine profiles and rejection patterns in xenotransplantation.     

Major Histocompatibility Complex Haplotype Is Associated with Postherpetic Pain in Mice

Background: Postherpetic neuralgia is one of the major complications of herpes zoster caused by the reactivation of varicella-zoster virus and is characterized by severe pain. The authors previously showed the association of a human major histocompatibility complex (MHC) haplotype with postherpetic neuralgia. This study was performed to experimentally confirm the role of MHC haplotype in the development of postherpetic pain using a mouse model of postherpetic pain, which corresponds to postherpetic neuralgia.

Methods: BALB/c mice (MHC haplotype: H-2d), C57BL/6 mice (MHC haplotype: H-2b), and BALB/b mice, a congenic BALB/c strain with H-2b, were used. Herpes simplex virus type I was transdermally inoculated on the hind paw. Unilaterally zosteriform skin lesion and pain-related responses (acute herpetic pain) were caused, and some mice showed pain-related responses (postherpetic pain) after the cure of skin lesions. Herpes simplex virus type I antigen and CD3-positive cells were immunostained in the dorsal root ganglion in the acute phase.

Results: The incidence (78%) of postherpetic pain in C57BL/6 mice was significantly higher than that (35%) in BALB/c mice (P = 0.004, odds ratio = 6.7). Furthermore, the incidence of postherpetic pain in BALB/b (H-2b) was similar to that in C57BL/6. Herpes simplex virus type I antigen-positive cells were less in the dorsal root ganglion of C57BL/6 mice than that of BALB/c mice. CD3-positive T cells were more in the dorsal root ganglion of C57BL/6 mice than BALB/c mice.     

Persistent renal and extrarenal immune changes after severe ischemic injury

BACKGROUND: Renal ischemia/reperfusion (I/R) injury is associated with delayed graft function and decreased long-term allograft function. However, most experimental studies evaluating renal I/R injury have focused on acute events after ischemia. T cells are potential candidates to link preservation injury, alloimmunity, and fibrosis. We hypothesized that severe renal I/R injury would generate long-term kidney damage and immune changes. METHODS: C57BL/6 mice underwent 60 minutes of warm unilateral I/R injury or sham surgery and were studied for 6 weeks. Serum creatinine, renal histology, and albumin excretion were measured. Phagocyte infiltration, CD4+ infiltration, renal cytokine expression, and splenic lymphocyte intracellular cytokine production were also measured in mice at 6 weeks. RESULTS: Serum creatinine levels rose following 60 minutes of unilateral I/R injury compared to sham mice. Histologic analysis of ischemic kidneys at 6 weeks revealed a pronounced loss of tubular architecture and infiltration of inflammatory cells. Phagocyte and CD4+ T-cell infiltration were significantly increased in ischemic kidneys. This was accompanied by a significant increase in interleukin (IL)-1beta and regulated upon activation, normal T-cell expressed and secreted (RANTES) expression. Despite similar splenic CD4 and CD8 numbers, intracellular cytokine staining of T cells revealed a significant increase in interferon-gamma (IFN-gamma) in I/R injury mice compared to sham mice. CONCLUSION: Persistent renal and extrarenal immune responses occur after a single episode of severe I/R injury. These immune processes resulting from injury could in turn have long-term consequences on progression of renal disease in transplanted and native kidneys.     

Major histocompatibility complex haplotype is associated with postherpetic pain in mice

BACKGROUND: Postherpetic neuralgia is one of the major complications of herpes zoster caused by the reactivation of varicella-zoster virus and is characterized by severe pain. The authors previously showed the association of a human major histocompatibility complex (MHC) haplotype with postherpetic neuralgia. This study was performed to experimentally confirm the role of MHC haplotype in the development of postherpetic pain using a mouse model of postherpetic pain, which corresponds to postherpetic neuralgia. METHODS: BALB/c mice (MHC haplotype: H-2), C57BL/6 mice (MHC haplotype: H-2), and BALB/b mice, a congenic BALB/c strain with H-2, were used. Herpes simplex virus type I was transdermally inoculated on the hind paw. Unilaterally zosteriform skin lesion and pain-related responses (acute herpetic pain) were caused, and some mice showed pain-related responses (postherpetic pain) after the cure of skin lesions. Herpes simplex virus type I antigen and CD3-positive cells were immunostained in the dorsal root ganglion in the acute phase. RESULTS: The incidence (78%) of postherpetic pain in C57BL/6 mice was significantly higher than that (35%) in BALB/c mice (P = 0.004, odds ratio = 6.7). Furthermore, the incidence of postherpetic pain in BALB/b (H-2) was similar to that in C57BL/6. Herpes simplex virus type I antigen-positive cells were less in the dorsal root ganglion of C57BL/6 mice than that of BALB/c mice. CD3-positive T cells were more in the dorsal root ganglion of C57BL/6 mice than BALB/c mice. CONCLUSIONS: These results suggest that the MHC haplotype (H-2) is involved in the incidence of postherpetic pain, and CD3-positive T cells may play a role in its pathogenesis.