Cold ischemic injury,aortic allograft vasculopathy,and pro-inflammatory cytokine expression

BACKGROUND: The aim of this study was to understand the role of ischemic preservation injury and pro-inflammatory cytokine expression in the progression of allograft vasculopathy. METHODS: Using the rat aortic transplant model, grafts were stored at 4 degrees C for either 1 or 24 h. Graft vasculopathy was assessed at 4 and 8 weeks after transplantation. Intra-graft cytokine expression was measured at days 1, 3 and, 7 after transplantation. RESULTS: At 4 weeks, intimal hyperplasia of allografts was greater than isografts (P<0.05). At 8 weeks, all groups had an increase in graft vascular disease compared to the 4-week groups (P<0.05). Allografts preserved for 24 h displayed a greater degree of vessel-wall reaction than both isograft groups and allografts stored for 1 h (P<0.05). An increased expression of the cytokines, TNF-alpha, TGF-beta, IL-2, INF-gamma, IL-1, and IL-6 was noted in the allografts stored for 24 h compared to similarly treated isografts (P<0.05). CONCLUSIONS: Prolonged ischemic preservation injury induced vascular disease in both isografts and allografts. The vessel wall reaction increased over time and was greater in allografts than isografts. The enhanced expression of T cell- and macrophage associated cytokines in allografts compared to isografts, suggested that early pro-inflammatory cytokine expression played an important role in progression of allograft vasculopathy.     

Blockade of Macrophage Colony-Stimulating Factor Reduces Macrophage Proliferation and Accumulation in Renal Allograft Rejection

Macrophage accumulation within an acutely rejecting allograft occurs by recruitment and local proliferation. To determine the importance of M-CSF in driving macrophage proliferation during acute rejection, we blocked the M-CSF receptor, c-fms, in a mouse model of acute renal allograft rejection. C57BL/6 mouse kidneys (allografts, n = 20) or BALB/c kidneys (isografts, n = 5) were transplanted into BALB/c mice. Anti-c-fms antibody (AFS98) or control Ig (50 mg/kg/day, i.p.) was given daily to allografts from days 0-5. All mice were killed day 6 postoperatively. Expression of the M-CSF receptor, c-fms, was restricted to infiltrating CD68+ macrophages. Blockade of c-fms reduced proliferating (CD68+/BrdU+) macrophages by 82% (1.1 v 6.2%, p < 0.001), interstitial CD68+ macrophage accumulation by 53% (595 v 1270/mm2, p < 0.001), and glomerular CD68+ macrophage accumulation by 71% (0.73 V 2.48 CD68+ cells per glomerulus, p < 0.001). Parameters of T-cell involvement (intragraft CD4+, CD8+ and CD25+ lymphocyte numbers) were not affected. The severity of tubulointerstitial rejection was reduced in the treatment group as shown by decreased tubulitis and tubular cell proliferation. Macrophage proliferation during acute allograft rejection is dependent on the interaction of M-CSF with its receptor c-fms. This pathway plays a significant and specific role in the accumulation of macrophages within a rejecting renal allograft.     

Interleukin-18 Affects Local Cytokine Expression But Does Not Impact on the Development of Kidney Allograft Rejection

Interleukin-18 is predominantly a macrophage-derived cytokine with a key role in inflammation and cell-mediated immunity. Having previously demonstrated IL-18 upregulation in a rat model of kidney rejection, here we examined IL-18 in a fully MHC-mismatched murine model of acute kidney rejection using IL-18-deficient recipients (IL-18-/-) and animals administered neutralizing IL-18 binding protein (IL-18BP). Gene expression of IL-18 and its receptor were significantly upregulated in allografts compared to isografts, as was the cellular infiltrate (T cells and macrophages) (p < 0.001). Allografts developed kidney dysfunction (p < 0.05) and tubulitis (p < 0.01) not observed in controls. There was a significant reduction in gene expression of IL-18 downstream pro-inflammatory molecules (iNOS, TNFalpha and IFNgamma) in IL-18-/- recipients (p < 0.01), and IL-18BP-treated animals. The CD4+ infiltrate and IL-4 mRNA expression was greater in the IL-18-/- recipients than wild-type (WT) allografts and IL-18BP-treated animals (p < 0.05), suggesting a Th2-bias which was supported by IFNgamma and IL-4 ELISPOT data and an increased eosinophil accumulation (p < 0.001). Neither IL-18 deficiency nor neutralization prevented renal dysfunction or tubulitis. This study demonstrates increased production of IL-18 in murine kidney allograft rejection and provides evidence that IL-18-induced pathways of inflammation are active. However, neither IL-18 deficiency nor neutralization was protective against the development of allograft rejection.     

Macrophage colony-stimulating factor expression and macrophage accumulation in renal allograft rejection

BACKGROUND: Studies of infiltrating cells from acutely rejecting renal allografts show that a high proportion of these cells are macrophages, and early macrophage infiltration is a poor prognostic sign for transplant survival. Macrophage colony-stimulating factor (M-CSF), produced by tubular and mesangial cells, has been associated with macrophage infiltration and proliferation in experimental and human kidney diseases. We investigated the expression of M-CSF in a model of acute rejection. METHODS: Lewis rats underwent bilateral nephrectomies and received an orthotopic Dark Agouti allograft or Lewis isograft. Animals received cyclosporine (10 mg/kg/day) from day 0 to day 3 and were killed at days 4, 8, or 14 after transplantation. Macrophages (ED1+) and T cells (W3-13+) were identified by immunohistochemistry, and M-CSF expression was identified by Northern blotting and in situ hybridization. RESULTS: Isografts had normal renal function without histological evidence of rejection. Allografts exhibited a moderate infiltrate at day 4 but progressed to severe rejection at day 14, with elevated serum creatinine level and severe tubulointerstitial damage. Macrophages and T cells were present in equal proportion in the infiltrate at day 4. At day 14, the number of macrophages increased fivefold (2580/mm2), although T cells were unchanged (380/mm2). Proliferating macrophages (ED1+, BrdU+) increased from day 4 (4%) to day 14 (10%). M-CSF mRNA expression was strongly up-regulated in allografts compared with isografts and normal rat. In situ hybridization demonstrated M-CSF expression by resident and infiltrating cells. Renal tubular expression was minimally increased at day 4 but strongly up-regulated at day 14 (more than 50% of tubules positive), particularly in areas of tubular damage. Tubular M-CSF expression colocalized with areas of intense macrophage infiltration and proliferation. Serial sections with double labeling demonstrated that T cells were the dominant source of M-CSF at day 4, yet later in the rejection (day 14) the predominant sites of production were both renal tubular cells and interstitial macrophages. CONCLUSIONS: Renal production of M-CSF by graft-infiltrating (macrophages and T lymphocytes) and resident (tubular) cells was up-regulated during acute rejection. M-CSF promotes macrophage recruitment and proliferation and may thereby play a pathogenic role in acute rejection. The kinetics of M-CSF production during acute rejection suggest that local macrophage proliferation may be initiated by T cells and perpetuated by both renal tubular and autocrine release.     

急性排斥反应过程中淋巴细胞趋化因子基因表达的意义

目的　探讨急性排斥反应过程中淋巴细胞趋化因子 (LTN)mRNA在移植心脏局部表达的意义及环孢素A(CsA)对其的影响。方法　以SD大鼠为受者 ,Wistar大鼠为供者 ,施行异位 (腹腔 )心脏移植术 ,分为术后使用CsA组 (15mg·kg-1·d-1)和不用组 ,并设SD大鼠间的心脏移植组 (同系移植组 ) ,以正常SD大鼠为对照组。采用一步法逆转录 聚合酶链反应 (RT PCR)检测术后不同时间移植心脏局部LTNmRNA的表达。结果　正常对照组和同系移植组在各时间点均未见LTNmRNA表达 ;LTNmRNA在未用CsA组的表达变化与急性排斥反应的进程相关 ,排斥反应的早期出现LTNmRNA表达上调 ,术后 5d时达到峰值 ,而应用CsA组 ,LTNmRNA的表达峰值出现延缓 ,且明显低于未用CsA组 (P <0 .0 5 )。结论　LTNmRNA的表达上调与排斥反应过程中淋巴细胞浸润密切相关 ,可能对急性排斥反应的早期诊断有帮助 ;CsA可抑制LTN基因的表达 ,可能是其免疫抑制作用的又一分子免疫学机制     

The relation between apoptosis of acinar cells and nitric oxide during acute rejection of pancreas transplantation in rats

Apoptosis is an important mechanism of immune-mediated graft damage. Nitric oxide (NO) generated by inducible NO synthase (iNOS) has been demonstrated to induce apoptosis. This study investigated whether apoptosis occurs during pancreas allograft rejection and examined the relationship of apoptosis of acinar cells and NO. The rats were divided into three groups: untreated isograft group, untreated allograft group and aminoguanidine (AG)-treated group. The pancreatic grafts were harvested on the post-transplantation day 3, 5 and 7 and were used to detect the histopathological rejection grade, the expression of iNOS and the apoptotic index (AI) of the graft. iNOS presented faint positive in the acinar cells of untreated isografts and did not change greatly after transplantation (P>0.05), the level of iNOS in the untreated allografts increased progressively (P<0.01) and at the same time point was significantly higher than that of untreated isograft group and AG-treated group (P<0.01). The transferase-mediated dUTP nick end labeling showed that the apoptotic cells were mainly acinar cells. A significant correlation between AI and iNOS was noted (P<0.01, r=0.611). Therefore, NO-mediated apoptosis of acinar cells plays an important role in acute rejection of pancreas transplantation, AG can mitigate the damage of pancreas allografts.     

急性排斥反应时Fractalkine及其受体在移植心脏中的表达

目的　探讨急性排斥反应过程中Fractalkine(FKN)及其受体CX3CR1在移植心脏局部表达的意义及环孢素A(CsA)对它们的影响。　方法　施行大鼠异位心脏移植术 ,移植大鼠分为 3组 ,每组 45只 ,对照组 5只。SD大鼠间的移植为同系移植组 (A组 ) ,Wistar至SD大鼠的移植分为未用CsA干预组 (B组 )及CsA干预组 (C组 ) ,健康SD大鼠为对照组。采用RT PCR方法检测排斥反应中移植心脏局部FKNmRNA的表达水平 ,免疫组化方法检测FKN和CX3CR1的蛋白表达水平。　结果FKNmRNA与蛋白在A组各时间点和对照组均呈低水平表达 ;在B组的表达变化与急性排斥反应的进程相关 ,术后第 7天FKNmRNA表达上调至峰值 (0 8± 0 2 6) ;C组应用CsA后 ,FKNmRNA表达峰值显著低于B组 (t=2 3 90 ,P <0 0 5 )。FKN和CX3CR1蛋白分别定位于移植心脏血管内皮细胞及间质浸润的单个核细胞中。　结论　急性排斥反应过程中 ,FKN及其受体CX3CR1表达上调 ,与移植物间质单个核细胞浸润密切相关 ;抑制FKN CX3CR1通路的活化可能是CsA发挥作用的又一分子免疫学机制     

Correlation between interleukin-15 and granzyme B expression and acute lung allograft rejection

The levels of interleukin (IL)-15 and granzyme B mRNA expression have been correlated with acute rejection episodes of kidney and heart allografts. Thus, the purpose of this study was to determine whether a correlation exists between the expression of IL-15 and granzyme B and acute lung allograft rejection. Toward this, the levels of IL-15 and granzyme B mRNA expression were determined in bronchoalveolar lavage-derived alveolar macrophages and total cells, respectively, from lung transplant patients with stable lung allograft function and patients undergoing acute rejection episodes. The expression levels of IL-15 mRNA was significantly higher in the patients undergoing acute rejection as compared to patients with stable lung function (P=0.02). The expression levels of granzyme B mRNA was also significantly higher in the patients undergoing acute rejection as compared to patients with stable lung function (P=0.005). The Receiver-Operating-Characteristic curve demonstrated that acute rejection can be predicted with a sensitivity of 94% and specificity of 67% with the use of a cutoff value of 3.1 fg of granzyme B mRNA per microgram of total RNA (or 71% sensitivity and 75% specificity of a cutoff value of 9.1 fg/microg). These data indicate that IL-15 secreted by activated alveolar macrophages and granzyme B secreted by activated CD8+ cytotoxic T lymphocytes play important roles in the process of acute lung allograft rejection.     

Determination of hindlimb transplantation-induced vascular albumin leakage and leukocyte activation during the acute phase of rejection

Following transplantation, the microvascular endothelium and endothelial cells play a critical role in allograft rejection, as well as response to surgical trauma. In this study, endothelial-cell damage was assessed through microvascular permeability, and the role of surgical trauma was evaluated during the acute phase of limb allograft rejection. Eighteen isograft and 18 allograft composite-tissue transplantations were performed between 72 rats. At 24-hr, 72-hr, and 7-days follow-up, microvascular permeability, leukocyte activation, functional capillary perfusion, red-blood-cell velocity, vessel diameter, and an endothelial edema index were measured. The permeability index (PI) was statistically significantly greater in the allografts at all follow-up points, compared with the isograft controls (p <0.001). The number of rolling leukocytes was significantly greater in the allografts at 24 and 72 hr; the number of sticking and transmigrating leukocytes was greater at all three follow-up points; and the number of rolling lymphocytes was greater at 7 days (p <0.05). These findings demonstrate the increased rejection phenomenon in allografts, and the increased susceptibility to ischemia and reperfusion injury, compared with isograft transplants. Increased leukocyte activation and acute destruction of endothelial-cell barrier function were demonstrated during the acute rejection period following composite limb allotransplantation.     

Time course and cellular localization of inducible nitric oxide synthases expression during cardiac allograft rejection

BACKGROUND: We have demonstrated that inhibition of inducible nitric oxide synthase (NOS) ameliorated acute cardiac allograft rejection. This study determined the time course and cellular localization of inducible NOS expression during the histologic progression of unmodified acute rat cardiac allograft rejection. METHODS: Tissue from syngeneic (ACI to ACI) and allogeneic (Lewis to ACI) transplants were harvested on postoperative days 3 through 10 and analyzed for inducible NOS mRNA expression (ribonuclease protection assay), inducible NOS enzyme activity (conversion of L-[3H]arginine to nitric oxide and L-[3H]citrulline), and nitric oxide production (serum nitrite/nitrate levels). Inducible NOS mRNA and protein expression were localized using in situ hybridization and immunohistochemistry. RESULTS: Inducible NOS mRNA and enzyme activity were expressed in allografts during mild, moderate, and severe acute rejection (postoperative days 4 through 10), but were not detected in normals, isografts, or allografts before histologic changes of mild acute rejection (postoperative day 3). Inducible NOS expression resulted in increased serum nitrite/nitrate levels during mild and moderate rejection (postoperative days 4 through 6). Inducible NOS mRNA and protein expression localized to infiltrating mononuclear inflammatory cells in allograft tissue sections during all stages of rejection but were not detected in allograft parenchymal cells or in normals or isografts. CONCLUSIONS: Inducible NOS expression and increased nitric oxide production occurred during the early stages of acute rejection, persisted throughout the unmodified rejection process, and localized to infiltrating inflammatory cells but not allograft parenchymal cells during all stages of acute rejection.     

Linking Inflammation to Acute Rejection in Small-For-Size Liver Allografts: The Potential Role of Early Macrophage Activation

This study aims to investigate the immunological status of small-for-size liver allografts and possible mechanism that contributes to the accelerated immune response in these allografts. Eight experimental groups were: whole isografts; 40% isografts; whole allografts, no treatment; 40% allografts, no treatment; whole allografts with sodium salicylate intraperitoneal injection, D0-3; 40% allografts with sodium salicylate, D0-3; whole allografts with FK506 intramuscular injection D0-3, and 40% allografts with FK506, D0-3. The 40% allografts survived significantly shorter than whole allografts (p=0.02). At 72 h after reperfusion, a higher number of macrophages infiltrated into the periportal area of small-for-size allografts than whole allografts. Remarkable up-regulation of interleukin-1beta (IL-1beta), interleukin-2 (IL-2), interleukin-10 (IL-10) and interferon-gamma (IFN-gamma) messenger RNA (mRNA) levels were detected in small-for-size allografts within 24 h after reperfusion. Sodium salicylate administration reduced IL-1beta and IFN-gamma mRNA in both small-for-size and whole allografts, but it could decrease IL-2 and IL-10 mRNA levels only in small-for-size allografts. In vitro study revealed that CD80, CD86 and CD11b expression on macrophages was augmented after IL-1beta stimulation, whereas the up-regulation could be blocked by sodium salicylate. In conclusion, early activation of macrophages as a result of graft injury might play an important role in the accelerated acute rejection process in small-for-size allografts.     

Macrophages act as effectors of tissue damage in acute renal allograft rejection

BACKGROUND: Macrophages constitute 38% to 60% of infiltrating cells during acute renal allograft rejection. Their contribution to tissue damage during acute rejection was examined by depleting macrophages in a rat model. METHODS: Lewis rats underwent bilateral nephrectomy and then received a Dark Agouti renal allograft and liposomal-clodronate, control phosphate-buffered saline liposomes, or saline intravenously (n=7 per group) on days 1 and 3 postsurgery. Grafts were harvested on day 5. RESULTS: Liposomal-clodronate treatment resulted in a 70% reduction in blood ED1+ monocytes and 60% reduction in intragraft ED1+ macrophages (both P<0.01). Half of all remaining interstitial ED1+ cells were undergoing apoptosis (terminal deoxynucleotide transferase-mediated dUTP nick-end labeling+/ED1+), and thus functional depletion of more than 75% of macrophages was achieved. Histologic and functional parameters of acute rejection were attenuated: interstitial infiltrate, tubulitis, and glomerulitis (P<0.01); tubular cell apoptosis (P<0.001); tubular cell proliferation (P<0.001); and serum creatinine (P<0.01). Production of inducible nitric oxide synthase by infiltrating cells and urinary nitric oxide excretion was reduced by 90% (P<0.001). In contrast, no reduction in the number of other leukocytes was seen (CD3+, CD4+, CD8+, and natural killer cells). Activation of lymphocytes (CD25+) and production of lymphocyte effector molecules (granzyme B) were unaltered. CONCLUSION: This study demonstrates that macrophages contribute to tissue damage during acute rejection.     

血小板源性生长因子A在大鼠移植心脏血管病变及纤维化中的作用

目的 探讨血小板源性生长因子A(PDGF-A)在移植心脏血管病变及心肌纤维化中的作用.方法 选择近交系健康雄性Wistar大鼠及SD大鼠,建立大鼠异位心脏移植模型.实验分为四组,每组8只.正常对照组:取正常Wistar大鼠的心脏作为空白对照.无排斥组:心脏移植的供、受者均为Wistar大鼠,移植后第60天取移植心脏.急性排斥组和慢性排斥组:心脏移植的供者均为Wistar大鼠,受者均为SD大鼠;急性排斥组术后未行免疫抑制治疗,术后第5天取移植心脏;慢性排斥组术后给予环孢素A 10 mg·kg-1·d-1,皮下注射,移植后第60天取移植心脏.采用免疫组织化学染色法检测移植心脏的巨噬细胞浸润(CD68阳性细胞数)情况;逆转录聚合酶链反应(RT-PCR)分析PDGF-A mRNA的表达水平.结果 正常对照组和无排斥组未见巨噬细胞浸润;急性排斥组巨噬细胞浸润主要见于心肌及冠状血管周围;慢性排斥组巨噬细胞浸润见于心肌及血管周围,在心肌坏死纤维化较严重的区域,巨噬细胞浸润尤为明显;正常对照组、无排斥组、急性排斥组和慢性排斥组移植心组织中PDGF-A mRNA的相对表达量分别为:0.26±0.06、0.31±0.04、0.88±0.12和0.94±0.11,慢性排斥组和急性排斥组中PDGF-A mRNA的相对表达量明显高于正常对照组和无排斥组(P＜0.01).结论 巨噬细胞浸润及血小板源性生长因子表达水平与移植心脏血管病变及心肌纤维化有关.     

排斥反应中移植心脏局部白细胞介素1βmRNA的表达状态

目的 探讨白细胞介素（IL）-1βmRNA在移植心脏局部表达状态与移植心脏自然生存时间的关系。方法 建立大鼠异位心脏移植模型,不同品系大鼠之间的移植供、受体分别为SD大鼠和Wistar大鼠（共66只）;同品系大鼠之间的移植供受体均为Wistar大鼠（共66只）。于术后第1、3、5、7、9、11天,分别切取移植心脏各6只,提取总RNA,将目的引物和对照引物在同一管中扩增,以两者象素值比值均数做曲线图,观察排斥反应时IL－1βmRNA的动态表达情况。结果 不同品系移植心脏的停跳高峰在术后第6－10天。排斥反应时移植心脏局部IL－1βmRNA的表达水平明显增高,峰值在术后第1天。结论 IL－1β在心脏移植排斥反应中可能起着重要作用,IL－1β mRNA的动态检测可望成为早期诊断排斥反应的指标。     

Characterization of allograft rejection in an experimental model of small intestinal transplantation

Graft rejection continues to be a major barrier to the success of clinical small intestinal transplantation. The objective of this study was to characterize histopathologic and immune parameters of allograft rejection in an experimental model of small intestinal transplantation. Heterotopic intestinal transplants were performed in allogeneic and isogeneic rat strain combinations. An additional group of allogeneic recipients was treated with tacrolimus (1 mg/kg/day) for 7 days beginning on posttransplant day 1. Recipients of allografts and isografts were killed on days 1 to 7 following transplantation, and tacrolimustreated allograft recipients were killed on days 4 and 7. Grafts and native intestines were examined for histopathology and cytokine gene expression. Very early rejection was observed on posttransplant day 3 and severe rejection was apparent by day 7. The key histopathologic features of acute graft rejection including apoptosis, crypt epithelial cell injury, and an inflammatory infiltrate were uniformly identifiable on day 4 and progressed in severity through day 7. Interleukin (IL)-2, IL-4, IL-5, IL-6, interferon-γ (IFN-γ), and tumor necrosis factor-γ mRNA were readily detectable in allografts on days 1 to 7. However, only IFN-γmRNA showed a significant early and sustained increase in allografts as compared to isografts and native intestine. Treatment of allograft recipients with tacrolimus abrogated the major histopathologic features of rejection and markedly inhibited IFN-γgene expression. These results indicate that graft rejection in small intestinal transplantation is characterized by a local and specific immune response marked by WN-γproduction that results in crypt epithelial cell injury and apoptosis. Tacrolimus abrogates the histopathologic features of rejection in association with a marked inhibition of IFN-γgene expression. Supported by grants from the Lucile Packard Foundation and the Office of Technology and Licensing, Stanford University     

Analysis of the Fas system and Bcl-2 in rat liver allograft rejection.

BACKGROUND: Apoptosis is involved in the mechanism of cell death observed in liver allograft rejection. The liver cells are sensitive to Fas-mediated apoptosis; however, little is known about the involvement of the Fas system in liver allograft rejection. We used rat models to investigate the expression of Fas/Fas ligand and apoptosis-related proteins during liver allograft rejection. MATERIALS AND METHODS: DA rats to Lewis, and Lewis to Lewis orthotopic liver transplantation were performed; liver samples were collected on days 1, 3, 5, 7, and 9 postoperatively (each n = 3). Apoptosis was monitored by TUNEL and electron microscopy. The expression of Fas, FasL, bcl-2, and bax was examined at the mRNA level and by means of immunohistochemistry. RESULTS: The TUNEL index in the allografts and isografts on day 7 was 20.1 +/- 1.5 and 7.7 +/- 2.6/1000 cells, respectively. Fas and bax mRNA were constitutively expressed in both of the groups. The expression of Fas ligand mRNA in the allografts which rose on day 5 was 10 times stronger compared to that in the isografts. On the other hand, bcl-2 mRNA was generally expressed in the isografts while it decreased in the allografts. The immunohistochemical analysis also showed an increased reactivity of Fas ligand on day 5 in the allograft, which was observed both in parenchymal and nonparenchymal cells. CONCLUSIONS: These results strongly suggest that Fas/Fas ligand interaction mediates the liver injury during allograft rejection. In addition, other regulatory factors of apoptosis, such as bcl-2, might also be involved in this pathogenesis.     

A comparison of gene expression in murine cardiac allografts and isografts by means DNA microarray analysis

BACKGROUND: Acute rejection of allografts remains a significant problem in clinical transplantation, and the fundamental mechanism underlying this rejection are as yet only poorly elucidated. Recently, DNA microarrays have come into use for the study of gene expression profiles, and we have taken advantage of this new technology to investigate acute rejection. We compared mRNA profiles in murine cardiac allografts with isografts using DNA microarrays with probe sets corresponding to more than 11,000 mice genes. METHODS: We screened for gene expression changes in murine cardiac allografts between fully incompatible mice strains (BALB/c H2d to C3H/He H2k) using a DNA microarray. The heart was heterotopically transplanted. Allografts (BALB/c to C3H/He) were removed on days 1, 3, and 5. As a control, isografts (C3H/He to C3H/He) harvested on days 1, 3, and 5 and native hearts of both strain mice (C3H/He and BALB/c) were obtained. RESULTS: On day 5, interferon-gamma (IFN-gamma) and many IFN-gamma-inducible genes were profoundly induced in the allograft relative to isograft. Monokine induced by IFN-gamma was most profoundly induced followed by inducibly expressed GTPase and Lmp-2. IFN-gamma was also profoundly induced. The induction was detectable from day 3. In contrast, genes regulated by other cytokines exhibited only modest changes. CONCLUSION: IFN-gamma-inducible genes are specifically up-regulated in murine cardiac allografts, suggesting that signaling mediated by IFN-gamma may play an important role in the late phase of acute rejection in vivo.