Influence of donor MHC class I antigen expression on graft survival after rat parathyroid allotransplantation

BACKGROUND AND AIMS: We investigated the influence of donor MHC antigen expression on graft survival after parathyroid transplantation in three different strain combinations. METHODS: MHC class I and II expression on parathyroid tissue of Lewis (LEW), Dark Agouti (DA), and Wistar-Furth (WF) rats was first analysed semiquantitatively by immunohistochemistry. Additionally, five groups were transplanted: (1) LEW to LEW, (2) DA to DA, (3) LEW to DA, (4) WF to LEW, and (5) DA to LEW. METHODS: MHC class I expression was strong in DA, moderate in WF, and weak in LEW rats; MHC class II expression was negative in all three strains. In the interstitium of all investigated tissue specimens, the proportion of MHC class II-expressing cells was low. RESULTS: After syngeneic transplantation, graft survival could be documented over the whole observation period. A mean graft survival of 20 (+/-2) days was observed following transplantation from LEW to DA, grafts in the group WF to LEW were rejected after 13 (+/-1) days, and graft function lasted 8 (+/-2) days in the group DA to LEW. The number of intragraft leukocytes expressing MHC class II molecules was equal in all groups, whereas increased levels of MHC class I on rat parathyroid tissue before transplantation resulted in a more rapid rejection. CONCLUSION: These results demonstrate that immunogenicity of rat parathyroid tissue seems to be determined by the amount of MHC class I expressed on donor parenchymal cells.     

Preoperative evaluation of microencapsulated human parathyroid tissue aids selection of the optimal bioartificial graft for human parathyroid allotransplantation

Allotransplantation of microencapsulated parathyroid tissue is a promising approach to the treatment of permanent hypoparathyroidism. Preoperative assessment of the quality of microencapsulated parathyroid tissue could facilitate selection of the optimal bioartifical graft for human parathyroid allotransplantation. Parathyroid tissue from patients with secondary hyperparathyroidism (n = 15) was processed mechanically or enzymatically (collagenase type II). Tissue particles and single cells/cell clusters were routinely microencapsulated with amitogenic Ba(2+) alginate. Parathyroid secretion dynamics in response to stimulation of nonencapsulated and microencapsulated parathyroid tissue with Ca(2+) were evaluated in a perifusion system. The stability of the different types of microcapsule was assessed using an osmotic pressure test. Mechanical cutting of parathyroid tissue led to peripheral necrosis of tissue particles and impaired their vitality. Collagenase digestion, in contrast, resulted in single cells and cell clusters without peripheral necrosis. The quality of microencapsulation of single cells/cell clusters was significantly better than that of tissue particles (deformed and imperfect capsules). Microencapsulation itself did not decrease cell vitality. Nonencapsulated and microencapsulated tissue particles and single cells/cell clusters from different donors maintained their own levels of response to stimulation with low Ca(2+). Microcapsules containing tissue particles showed poor stability compared with those containing single cells/cell clusters. Preoperative evaluation of microencapsulated parathyroid tissue can disclose differences in vitality and function and thus facilitate selection of the optimal bioartifical graft for human parathyroid allotransplantation.     

The influence of MHC class II antigen blockade by perfusion with a monoclonal antibody on rat renal graft survival

To decrease immunogenicity of the rat kidney, grafts were perfused with an anti-MHC class II monoclonal antibody (mAb). How effectively this procedure blocked class II-positive cells, which were mainly dendritic in appearance, was checked by immunostaining renal sections after perfusion and comparing them with in vitro stained sections. Optimum conditions were applied for graft pretreatment before transplantation. This procedure prolonged graft survival, though not satisfactorily from the biological point of view (9.6±0.8 versus 7.7±0.5 days in the control group; P<0.02). The dendritic cells were not killed but blocked. Several hours after transplantation, the mAb dissociated from these class II-positive cells. It was also shown that donor cells migrate into the recipient's spleen early after transplantation. The number of these cells was smaller when the transplanted organ was perfused with the mAb. Further studies are suggested to deplete the graft of donor dendritic cells more adequately. They should also combine graft perfusion with anticlass II mAb and recipient immunosuppression at reduced doses.     

The influence of MHC class II antigen blockade by perfusion with a monoclonal antibody on rat renal graft survival

Abstract. To decrease immunogenicity of the rat kidney, grafts were perfused with an anti-MHC class II monoclonal antibody (mAb). How effectively this procedure blocked class II-positive cells, which were mainly dendritic in appearance, was checked by immunostaining renal sections after perfusion and comparing them with in vitro stained sections. Optimum conditions were applied for graft pretreatment before transplantation. This procedure prolonged graft survival, though not satisfactorily from the biological point of view (9.6 ± 0.8 versus 7.7 ± 0.5 days in the control group; P < 0.02). The dendritic cells were not killed but blocked. Several hours after transplantation, the mAb dissociated from these class II-positive cells. It was also shown that donor cells migrate into the recipient's spleen early after transplantation. The number of these cells was smaller when the transplanted organ was perfused with the mAb. Further studies are suggested to deplete the graft of donor dendritic cells more adequately. They should also combine graft perfusion with anti-class II mAb and recipient immunosuppression at reduced doses.     

供体抗原经门静脉处理及移植物从门静脉回流对大鼠胰腺移植物功能存活的影响

以35只雄性SD大鼠为受体，制成糖尿病模型，以同龄Wistar雄性大鼠为供体，行全胰腺移植。供体抗原分别经门静脉或周围静脉处理，处理时间分别为移植前预处理或移植时处理，移植物静脉分别从门静脉或下腔静脉回流，结果表明供体抗原经门静脉预处理及移植物从门静脉回流对胰腺移植物功能存活的延长具有协同效应，移植时处理延长胰腺移植物效果不如移植前预处理，但可能具有一定的实用意义。     

供体抗原注入胸腺处理对大鼠胰腺移植功能存活的影响

在大鼠胰腺移植模型上将供体Ｗｉｓｔａｒ大鼠的脾细胞于移植前或移植时注入受体ＳＤ大鼠胸腺内，辅以短期免疫抑制剂，结果显示能明显延长胰腺移植物功能存活。崦单纯短期免疫抑制剂或单纯供体脾细胞注入胸腺均未能延长胰腺功能存活。提示供体脾细胞注入胸腺预处理延长胰腺功能存活效果优于移植时处理，但移植时处理可能更有实用价值。     

Effects of fish oil on graft arteriosclerosis and MHC class II antigen expression in rat heterotopic cardiac allografts.

The effect of fish oil on accelerated graft coronary arteriosclerosis was assessed in Lewis to Brown-Norway rat heterotopic cardiac allografts. Twelve Brown-Norway rats were supplemented with 2 ml/kg/day of fish oil (68.3 mg eicosopentaenoic acid and 47.5 mg decosahexaenoic acid per milliliter). Eleven additional animals, receiving an isocaloric amount of safflower oil, served as control. All diets began 1 week before operation. Immunosuppression was obtained with low-dose cyclosporine (2 mg/kg/d). When killed (100 days), there were no significant differences in percentage weight gain, graft function, or histologic rejection score. Although lipid profiles were comparable, total cholesterol:high-density lipoprotein ratio was marginally higher in animals treated with fish oil (p = 0.069). Mean percentage luminal occlusion (before and after correcting for differences in size between coronary vessels analyzed) and average intimal thickness were similar between animals treated with fish oil and safflower oil as assessed by computer-assisted digitized, morphometric planimetry. In all allografts, donor interstitial dendritic cells were repopulated with recipient dendritic cells. The major histocompatibility complex class II cell density in the fish oil group did not differ significantly from rats supplemented with safflower oil (1.48 +/- 0.68 vs 1.48 +/- 0.65 cells per mm2, p = 0.995). In conclusion, fish oil did not exert any beneficial effect over safflower oil in terms of graft coronary arteriosclerosis, histologic rejection, or plasma lipids.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sharing cross-reactive groups of MHC class I improves long-term graft survival

BACKGROUND: Renal transplant loss from chronic rejection remains substantial. To increase our understanding of this syndrome, we identified risk factors predicting late graft loss, with a special emphasis on the impact of human lymphocyte antigen (HLA) matching. METHODS: We studied all 654 cadaveric kidney transplants performed in our center between 1983 and 1996 that had survived for more than six months. Eighty-two transplants, lost because of chronic rejection, were used as the outcome variable. The influence of HLA mismatches and shares on long-term graft survival was evaluated at the level of private antigens and cross-reactive groups (CREG) of multiple histocompatibility complex (MHC) class I. HLA and other recipient, donors and transplant parameters were studied using univariate and multivariate Cox regression analysis. RESULTS: The cohort had a mean number of 1.9 HLA mismatches. Because of the homozygosity of HLA antigens, HLA mismatches were not reciprocal to shares. CREG and HLA-A-B mismatches had a relative risk for graft loss of 1.19 (95% CI, 0.97 to 1.45) and 1.05 (0.84 to 1.32) per mismatch. In contrast, the relative risk per shared CREG and broad HLA-A-B antigen was 0.76 (0.63 to 0.92) and 0.79 (0.61 to 1.03). Multivariate analysis revealed that individuals sharing less than four CREGs had a relative risk of 2.13 (1.29 to 3.75) for late graft loss. Other independent predictors were a recipient age of less than 50 years, relative risk 1.95 (1.02 to 3.71); a donor age of more than 50 years, relative risk 1.68 (1.01 to 2.80); acute rejection (vascular vs. no rejection), relative risk 3.52 (1.72 to 7.18); proteinuria (dipstick > 1+ vs. negative), relative risk 2.86 (1.29 to 6.35); and a serum creatinine concentration of more than 150 micromol/liter at six months, relative risk 3.41 (1.96 to 5.94). CONCLUSION: We identified several coexisting recipient-, donor-, and transplant-related risk factors for graft loss from chronic rejection. In this well-matched group of renal transplants, HLA mismatches and shares had a nonreciprocal relationship. Sharing of HLA antigens, especially CREG of MHC class I, was associated with improved long-term survival.     

The relationship of class I MHC antigen expression to stage IV-S disease and survival in neuroblastoma

Cultured human neuroblastoma cells express low levels of class I (MHC) surface antigen. In order to determine if this low expression is representative of the clinical tumor, this study investigates class I expression in archival human neuroblastoma. Whereas stages I to IV neuroblastoma expressed low levels of class I antigen, stage IV-S tumor cells expressed normal levels, similar to control tissues. Expression of class I antigen in tumors from survivors of stage III neuroblastoma was significantly greater than in tumors from nonsurvivors. Tumors comprised predominantly of ganglion cells expressed significantly more class I antigen than neuroblasts. These data suggest that class I MHC expression may play a role in the natural history of human neuroblastoma.     

Multiple patterns of MHC class II antigen expression on cellular constituents of rat heart grafts. Lack of correlation with graft survival, but strong correlation with vasculitis

The patterns of induced major histocompatibility antigen expression on indigenous cellular elements of heterotopic rat cardiac grafts were determined by immunohistologic methods in a variety of donor-recipient combinations. Heart grafts were studied in combined full-MHC- and non-MHC-disparate combinations, isolated intra-MHC-disparate combinations, and non-MHC-disparate combinations. The pattern of class II expression on cellular constituents of the grafts was highly variable and critically dependent upon the nature of the specific unidirectional donor-recipient combination. No uniform pattern of class II expression emerged that was clearly predictive of rapidity of rejection or of protracted survival. However, vasculitis was confined to grafts in combinations in which induced class II expression on graft large vessel endothelium was present. Sites of vasculitis were never encountered in the absence of induced class II expression on overlying endothelium. Vasculitis and associated induced class II expression on large vessel endothelium were present in rapidly rejecting grafts and in grafts with indefinite survival. In the latter, vasculitis was shown to progress to a late phase of occlusive intimal thickening. Induced class I expression on graft cardiac myofibers was present in all the genetically disparate donor-recipient combinations examined in this study, irrespective of the length of graft survival. This investigation has shown that no uniform stereotyped pattern of MHC antigen expression on cellular constituents correlates with the length of graft survival. However, induced class II expression on graft large vessel endothelium is closely associated with vasculitis, which can directly progress to occlusive intimal thickening in grafts with prolonged survival.     

Influence of previous immunization on skin graft survival.

The results of skin grafts transplanted in immunized and nonimmunized recipients was analysed. Specific sensitization for HLA-A or B determinants shortens graft survival if the recipients were immunized by s.c. injections of leukocytes. When the recipients had been pregnant, no such influence of specific HLA-A or B sensitization could be demonstrated. The variance in mean survival times of grafts exchanged between mixed lymphocyte culture (MLC)-positive donor-recipient combinations was significantly smaller than the variance in mean survival time (MST) of grafts exchanged between MLC-negative combinations. This difference could be the result of the influence of allograft immune-activating determinants of different strength in the MLC-negative donor-recipient combinations. Also the variance in MST of grafts in immunized recipients was significantly larger than the variance in MST of grafts in nonimmunized recipients. Apart from the obvious effect of HLA-A and B sensitization, other less well documented factors must have influenced graft survival. We did not find evidence for a graft enhancing effect of B cell-specific antibodies.     

Influence of cadaver donor age on renal graft survival

It has been suggested that kidneys from young and old donors do less well after transplantation. We have studied this problem in a retrospective analysis of all cadaveric transplants performed in our center during the last 10 years. All patients were followed for at least six months. Recipients younger than 16 years were excluded from this analysis. Thirty-six patients received a kidney from a donor younger than 11 years (group A), 374 received a kidney from a donor aged between 11 and 51 years (group B) and 21 a kidney from a donor aged older than 51 years (group C). In the young donor age group graft survival was significantly worse than in the two other groups with a one year graft survival of 45.6%, 75.0% and 75.9% for group A, B and C respectively. There were significantly more technical failures in group A, but if these were excluded a significant difference in graft survival remained present. At three months there were no significant differences in hypertension, proteinuria, or serum creatinine between the three groups. These results suggest that young but not old donor kidneys have a worse graft survival. This decreased graft survival is only partly caused by technical problems. Therefore young grafts also seem to be more susceptible to the host's immune response.     

受体猪表达供体MHCⅡDRβ分子对肝移植物存活的影响

目的 通过回输表达供体部分MHCⅡDRβ分子的自体骨髓细胞，观察受体对供体肝移植物的排斥情况。方法 将供体猪MHCⅡDRβ分子进行克隆，并通过基因重组技术将其克隆到反转录病毒载体pLNCX2上，经过细胞学操作获得有感染性的病毒颗粒；体外感染受体骨髓细胞，并将感染后的骨髓细胞回输给受体，随后采用Nothern杂交和逆转录-聚合酶链反应（RT-PCR）等方法检测供体基因的表达，并通过MLR反应检测受体对供体的免疫排异反应；之后进行全肝脏移植实验，观测移植物的排异反应。结果 实验组6头受体全部有外源基因的表达；进行回输后受体免疫功能都基本回复，MLR检测显示受体对供体的反应性明显下降，而对第三方的有较强的排异反应；进行移植后实验组中的5头移植物存活良好，而对照组于12～18周先后死亡，两者差异有统计学意义（P＜0.05）。结论 猪受体在接受供体肝脏移植前，如果用供体的部分MHCⅡDRβ分子进行修饰并在体内进行表达，可以明显延长移植物的存活时间。