C4d deposition is associated with chronic allograft nephropathy in rats and could be influenced by immunosuppressants

Aims

Deposition of C4d in peritubular capillaries (PTC) has been considered to be a marker of humoral immunity in renal transplant. This study is to investigate C4d deposition in rat renal allografts undergoing CAN and the effects of immunosuppressants on it.

Methods

Fisher 344 rat renal grafts were orthotopically transplanted into Lewis rats following the procedure of Kamada with our modification. All the recipients were given CsA 10 mg/kg⁻¹ · d⁻¹ × 10 d and then divided into 5 groups (each n = 9); (1) Vehicle: vehicle orally, (2) CsA: 6 mg/kg⁻¹ · d⁻¹, (3) RAPA: 0.8 mg/kg⁻¹ · d⁻¹, (4) FK 506: 0.15 mg/kg⁻¹ · d⁻¹, (5) MMF: 20 mg/ kg⁻¹ · d⁻¹. At 4 weeks, 8 weeks, 12 weeks, the rats were sacrificed, renal allografts were harvested and sera were collected. The deposition of C4d was detected by immunofluorescence and analyzed by Integrated Optical Density (IOD). The pathological changes were accessed according to the Banff 97 criteria.

Results

C4d deposition in PTC was found in all the allografts at 4 weeks, while there was no obvious manifestations of CAN in all the groups; the differences of Banff Score between all groups were not significant (P > .05). The values of IOD in RAPA and MMF group were lower than those in other 3 groups (P = .002, .006). The differences between RAPA and MMF, and between other 3 groups were not significant (P > .05). The intensity of C4d increased along with the progression of CAN, the heaviest C4d deposits in PTC were found at 12 weeks, and meanwhile the severest CAN was found. Comparing with Vehicle group, CsA and FK 506 had no effect on C4d deposition (P > .05), however, MMF and RAPA obviously decreased the C4d deposition (P = .000). The intensity of C4d deposition had a significant correlation with the severity of CAN (r = 0.894, P = .000).

Conclusions

Our study suggests that the deposition of C4d in allografts appears earlier than pathological changes of CAN and has a correlation with the progression of CAN. MMF and RAPA can attenuate CAN by inhibiting humoral immunity. In contrast, CsA and FK 506 have no effect on humoral immunity.     

Capillary deposition of the complement fragment C4d in cardiac allograft biopsies is associated with allograft vasculopathy

Cardiac allograft vasculopathy (CAV) is a long-term threat in heart transplant recipients and its exact pathogenesis remains to be established. As complement activation contributes to early and late allograft dysfunction, we hypothesized that deposition of the complement fragment, C4d, in capillaries of cardiac allograft biopsies may be associated with CAV. A polyclonal anti-C4d antibody was used for immunohistochemistry on endomyocardial biopsies obtained from heart transplant recipients during the first year post-transplantation. CAV was assessed by intracoronary ultrasound performed at 1-year post-transplantation. We were able to show that CAV is highly associated with C4d deposition in capillaries of cardiac allografts and that serial C4d studies may predict development of CAV at 1-year post-transplantation.     

Interstitial expression of heat-shock protein 47 correlates with capillary deposition of complement split product C4d in chronic allograft nephropathy

BACKGROUND: Chronic allograft nephropathy (CAN), associated with late-allograft dysfunction is caused by alloantigen-dependent and -independent mechanisms, and eventually leads to interstitial fibrosis (ci). Activation of complement cascade is considered to be a poor prognostic marker of graft survival. This study was designed to examine the relationship between the expression of C4d and heat-shock protein 47 (HSP47, a collagen-specific chaperone) in the development of interstitial fibroproliferative lesions in CAN. METHODS: Sixty-three renal allograft biopsy specimens, obtained from 48 patients, were examined for the expression of C4d, HSP47, CD68 and alpha-smooth muscle actin (alpha-SMA) by immunohistochemistry. Double-staining was performed to determine the colocalization of C4d and HSP47. The relationship of between the expression of C4d, HSP47, CD68 and alpha-SMA and the clinical and histopathological parameters were statistically analysed. RESULTS: No expression of C4d was noted in the tubulointerstitium including peritubular capillary (PTC) of the control kidney. C4d was expressed in PTC in one-third of allograft renal tissues with morphological evidences of CAN. The interstitial cells around the fibrotic areas of the PTC of CAN were positive for the expression of HSP47. The deposition of C4d in PTC correlated with interstitial expression of HSP47 around the PTC. Most HSP47 expressing cells were phenotypically altered myofibroblasts, as determined by the dual staining of alpha-SMA. CONCLUSIONS: The increased expression of HSP47 positively correlated with the expression of C4d in PTC, and might contribute to the progression of interstitial ci in CAN.     

大鼠肾移植后抗波形蛋白抗体升高与慢性移植肾肾病的相关性

目的 研究大鼠肾移植术后抗波形蛋白抗体的表达水平与慢性移植肾肾病(CAN)的相关性.以及不同免疫抑制剂对其的影响.方法 选取近交系F344大鼠作为同系肾移植的供、受者(共9对),选取F344和Lewis大鼠分别作为同种肾移植的供、受者(共27对).同系移植组受者术后不给予免疫抑制剂;同种移植组受者术后10 d内给予环孢素A(CsA),然后将同种移植组受者随机平均分为生理盐水(NS)组、CsA组和霉酚酸酯(MMF)组(每组9只),分别给予NS、CsA和MMF灌胃.术后第4、8和12周时分别处死每组受者3只,观察CAN的进展、波形蛋白及其基因的表达以及抗波形蛋白抗体的水平,取正常大鼠(包括F344和Lewis大鼠)作为对照.结果 观察期内同系移植组未发生CAN;而同种移植组发生了CAN,且不断加重,其中CsA组和NS组的CAN病理改变非常明显,而MMF组明显较轻.术前所有受者血清中均未检测到抗波形蛋白IgM和IgG抗体,术后也未检测到抗波形蛋白IgM抗体;术后同系移植组仅检测到微量的抗波形蛋白IgG抗体,同种移植组检测到大量的抗波形蛋白IgG抗体.随着CAN的进展,同种移植中,CsA组和NS组血清抗波形蛋白IgG抗体的水平逐渐增高,而MMF组抗体水平的增高显著低于NS组(P<0.05),但仍显著高于同系移植组(P<0.05).结论 大鼠同种肾移植术后,受者体内可产生抗波形蛋白IgG抗体,且产生的时间早于CAN,抗波形蛋白IgG抗体水平也会随着CAN的进展而增高.MMF可抑制抗波形蛋白IgG抗体的产生,CsA无此作用.     

移植肾组织中补体C4d沉积在CAN的诊断和治疗中的临床意义

目的 探讨移植肾组织中补体C4d沉积在慢性移植肾肾病(CAN)的诊断和治疗中的临床意义.方法 将2000年1月至2008年8月间诊断为CAN,且已行移植肾活检,并能收集到活检后2年以上随访资料者纳入研究.符合标准者共有86例,其中男性53例,女性33例,移植时年龄18～65岁.应用免疫组织化学染色方法检测移植肾组织活检标本C4d的表达.所有患者在行移植肾穿刺诊断为CAN后均给予了常规治疗.结果 86例患者中,C4d沉积阳性者(C4d阳性组)39例,C4d沉积阴性者(C4d阴性组)47例,两组患者在性别、年龄、供肾来源、多次移植、移植时群体反应性抗体水平等各指标的比较,差异均无统计学意义(P＞0.05).活检2年后,C4d阳性组和阴性组患者的SCr水平分别为(551.5±140.4)和(443.0±133.1)μmol/L,两组比较,差异有统计学意义(P＜0.05);并且C4d阳性组患者移植肾功能丧失率(23.1%,10/39)也显著高于C4d阴性组(8.5%,4/47),两组比较,差异有统计学意义(P＜0.05).CAN治疗前,C4d阳性组发生高血压和高血脂者多于阴性组(P＜0.05);常规治疗后,剔除移植肾功能丧失者,两组间发生高血压、高血脂、高血糖和高血尿酸者差异无统计学意义(P＞0.05).结论 C4d阳性的CAN患者提示有慢性体液排斥反应的参与,临床常规治疗预后较差,若针对体液免疫反应进行干预,能够改善移植肾长期存活.     

C4d complement split product in diagnosis of immunological activity of chronic allograft nephropathy

INTRODUCTION: Activation of the humoral branch of the immunological response is currently believed to play an important role in pathogenesis of chronic allograft nephropathy. The impact of humoral alloreactivity, indicated by the presence of C4d deposits in peritubular capillaries of a renal allograft, on the development of chronic allograft nephropathy is a significant problem in transplantation. The aim of the study was to assess and correlate C4d expression in patients with chronic allograft nephropathy, with clinical and morphological variables, as well as to assess the impact of a change in immunosuppression regimen on posttransplant course and renal allograft morphology. PATIENTS AND METHODS: Twenty-six patients with chronic allograft nephropathy underwent biopsies to correlate C4d expression with clinical parameters and morphological findings. In all patients azathioprine was replaced with mycophenolate mofetil with additional CsA dose reduction in 12 patients. After 1 year, 14 protocol biopsies were performed. RESULTS: The frequency of C4d peritubular capillary deposition among patients with chronic allograft nephropathy was 30%. C4d expression appeared later after transplantation, was correlated with chronic allograft glomerulopathy and proteinuria but not other clinical or histological variables. C4d deposits displayed no independent impact on serum creatinine level. Proteinuria was significantly more reduced in the C4d(+) group. Progression of chronic morphological changes was significantly accelerated in the C4d(+) group. CONCLUSION: C4d peritubular capillary expression did not differentiate patients after immunosuppression enhancement, but it predisposed to progression of chronic morphological findings during 1-year observation.     

C4d deposition in early renal allograft protocol biopsies

BACKGROUND: Deposition of the complement protein C4d in renal allograft biopsies obtained during graft dysfunction and rejection has been proposed to be a sensitive marker of antibody-mediated acute rejection. To determine the diagnostic specificity of C4d deposition, it is important to study biopsies from allografts with no evidence of dysfunction. In this study, we examined C4d deposition in protocol biopsies obtained irrespective of clinical status. METHODS: Immunohistochemistry for C4d was performed on routine protocol biopsies preimplantation and on day 7 posttransplantation from 48 unselected renal allografts. Serum samples obtained up to 1 month after transplantation were assayed for donor-reactive antibodies (DRA). Results were correlated with histopathology and clinical outcome measures. RESULTS: Diffuse C4d deposition was detected in the peritubular capillaries of 6 of 48 (13%) biopsies. C4d deposition was present in 5 of 15 (33%) biopsies that showed acute rejection (Banff 97, category 4) but only in 1 of 33 (3%) biopsies with no rejection (P=0.003, 97% specificity). Posttransplant DRAs were detected in 21 of 48 (44%) patients. All five recipients with C4d deposition and rejection had posttransplant DRA; the recipient whose biopsy showed C4d positivity, but not rejection, did not have detectable DRA. C4d deposition was not treated with plasmapheresis or intravenous immunoglobulin and was not associated with poor posttransplant graft outcome at 1-year follow-up. CONCLUSIONS: Our results show that in early posttransplant protocol biopsies, C4d is a specific marker for the presence of humoral rejection, as indicated by its association with DRA and acute histologic rejection.     

C4d deposition is associated with immune cells infiltrating in kidney allograft glomerulitis and peritubular capillaritis

Abstract

Objective: The aim of our study was to determine the amount and composition of immune cells within glomeruli and PTCs and its relationship with C4d deposition. Materials and methods: Immunohistochemistry staining for C4d, CD3, CD68, granzyme B and Foxp3 was used for phenotyping and enumerating immune cells within intracapillaries. Results: C4d staining was present in 26 biopsy specimens (C4d⁺) and negative in 25 specimens (C4d^?). The total number of infiltrating cells in glomerulus and PTC in C4d⁺ was significantly higher than in C4d^?. Although the C4d⁺ showed a significantly higher mean number of macrophages per glomerulus and PTC than in C4d^? group, the C4d^? showed a higher mean number of T cells per glomerulus and PTC than in C4d⁺. Comparing cell counts in diffuse C4d⁺ and focal C4d⁺ groups, a significant difference of absolute numbers of intracapillary cells could be observed in glomeruli and PTCs. The mean number of macrophages per glomerulus and PTC in diffuse C4d⁺ was greater than that of the focal C4d⁺, while mean T cells per glomerulus and PTC were less in cases of diffuse C4d⁺ than in focal C4d⁺. The differences, however, did not achieve statistical significance. Not only glomerular T cells but also PTCs are granzyme B positive T cells totally. Conclusion: The total number of infiltrating cells in glomeruli and PTC has association with PTC C4d deposition; the infiltrating cells were predominantly macrophages in C4d⁺, especially in diffuse C4d⁺, whereas the infiltrating cells were predominantly T cells in C4d^?. Glomerular and PTC T cells were cytotoxic phenotype completely.     

Endothelial C4d deposition is associated with inferior kidney allograft outcome independently of cellular rejection.

BACKGROUND: Capillary deposition of complement split product C4d has been suggested to be a valuable marker for humoral rejection. In this retrospective study we evaluated the clinical impact of C4d deposition in renal allografts with special emphasis on associations between C4d staining patterns and histological features of acute rejection. METHODS: One hundred and two allograft biopsies obtained from 61 kidney transplants (1-532 days after transplantation; median 14 days) were examined by immunohistochemistry on routine paraffin sections using a novel anti-C4d polyclonal antibody (C4dpAb). RESULTS: Fourty-two of 102 biopsies showed endothelial C4d deposits in peritubular capillaries (PTC). Histopathological analysis revealed a significantly lower frequency of positive C4d staining in biopsies with rather than in those without acute cellular rejection defined by the Banff grading schema (P<0.01). For clinical evaluation, patients were classified according to C4d staining in allografts (C4d(PTC) positive in at least one biopsy, n=31 vs C4d(PTC) negative in all biopsies, n=30). C4d(PTC) positive patients had significantly higher serum creatinine levels than C4d negative patients. Even in the absence of morphological evidence for rejection, differences in serum creatinine levels between C4d(PTC) positive and negative recipients were significant (6 months: 2.01+/-0.75 vs 1.41+/-0.27 mg/dl; 12 months: 1.95+/-0.60 vs 1.36+/- 0.34 mg/dl; 18 months: 1.98+/-0.50 vs 1.47+/-0.31 mg/dl; P<0.05). All patients with rejection resistant to conventional therapy (n=4) were in the C4d(PTC) positive subgroup. All recipients with panel reactive antibodies (PRA) >50% (n=8) were C4d(PTC) positive. CONCLUSIONS: Our data indicate that endothelial C4d deposition is associated with inferior graft outcome. We provide evidence that this immunohistochemical finding and its clinical impact are not associated with morphological signs of cellular rejection.     

Capillary deposition of complement C4d and C3d in pediatric renal allograft biopsies

BACKGROUND: Peritubular capillary deposition of C4d (C4d(PTC)) is a marker of antibody-mediated alloresponse and is associated with poor graft survival in adults. C3d(PTC) has received less attention; its significance is unclear. To date no information has been gained in children. METHODS: The prevalence of C4d(PTC) and C3d(PTC) in pediatric renal allograft biopsies (n=77, 31 cadaveric kidneys) was analyzed retrospectively. Associations with histology, donor-specific antibodies (DSAs), and outcome were investigated. RESULTS: The overall prevalence of C4d(PTC) and C3d(PTC) was 52% and 48%, respectively. C3d(PTC) was associated with C4d(PTC) (P<0.0001). Thirty-six percent of acute rejections were cellular, 28% were humoral, and 36% were combined cellular and humoral. C3d(PTC) was found in 57% of acute rejection biopsies. C4d(PTC), but not C3d(PTC), was associated with accumulation of polymorphonuclear cells in peritubular capillaries (P=0.02). Fifty-one percent of late biopsies (>6 months posttransplantation) had features of chronic allograft nephropathy: 50% were C4d(PTC_ positive, and 50% were C3d(PTC) positive. C4d(PTC) positive chronic allograft nephropathy biopsies had more transplant glomerulopathy (P=0.020) and mesangial matrix increase (P=0.026). C3d(PTC) tended to be associated with transplant glomerulopathy (P=0.06), but not with mesangial matrix increase. C4d(PTC) was correlated with DSA (P=0.011). Excluding early nonrejection graft losses, more grafts were lost in the C4d(PTC) positive group (P=0.019). C3d(PTC) was not associated with DSA or graft outcome. CONCLUSIONS: Our results support C4d(PTC) being a hallmark of humoral rejection in pediatric renal transplantation; its presence was associated with DSA and poorer immunologic graft outcome. In contrast, C3d(PTC), although highly associated with C4d(PTC), did not correlate with DSA or outcome.     

Noninvasive quantification of intrarenal allograft C4d deposition with targeted ultrasound imaging

Antibody‐mediated rejection (AMR) has emerged as a major cause of renal allograft dysfunction. C4d, a specific marker for AMR diagnosis, was strongly recommended for routine surveillance; however, currently, C4d detection is dependent upon tissue biopsy, which is invasive and provides only local semi‐quantitative data. Targeted ultrasound imaging has been used extensively for noninvasive and real‐time molecular detection with advantages of high specificity and sensitivity. In this study, we designed C4d‐targeted microbubbles (MB_C4d) using a streptavidin‐biotin conjugated method and detected C4d deposition in vivo in a rat model of AMR by enhanced ultrasound imaging. This noninvasive procedure allowed successful acquisition of the first qualitative image of C4d deposition in a wide renal allograft section, which reflected real‐time C4d distribution in grafts. Moreover, we introduced normal intensity difference for quantitative analysis, which exhibited a nearly linear correlation with the grade of C4d deposition according to pathologic analysis. In addition, this approach showed no influence on survival rates and pathologic features in the microbubble injection groups, thereby demonstrating its safety. These findings demonstrated a simple, noninvasive, quantitative, and safe evaluation method for C4d, with the utility of this approach potentially preventing patients from having to undergo an invasive biopsy.     

C4d deposition in allograft renal biopsies is an independent risk factor for graft failure

Aim:   Association between C4d deposition and renal allograft survival is still uncertain. We retrospectively evaluated the clinical outcome of C4d deposition in allograft renal biopsies.
Methods:   One hundred and fifty biopsies from 150 patients with a histological diagnosis of acute rejection from December 1997 to March 2007 were included. Paraffin-embedded sections were stained with a polyclonal antibody using an immunoperoxidase technique. Detailed clinical data were obtained by retrospective review.
Results:   C4d was stained positively in 74 (49.3%) of 150 cases: 47 (61.5%) biopsies showed diffuse C4d deposition and 27 (38.5%) showed focal C4d deposition. During follow up, significantly more C4d-positive patients (24/74 patients, 32.4%) lost their grafts, compared with the C4d-negative group (10/76 patients, 13.2%) ( P  = 0.005). After a Kaplan–Meier analysis, grafts from the C4d-negative group had a markedly higher survival as compared with the C4d-positive group ( P  = 0.003, log–rank test). Graft survival among C4d-negative, C4d diffuse-positive, and C4d focal-positive groups was significantly different ( P  = 0.007, log–rank test). The graft survival rate among C4d-negative patients in early (<6 months) and later biopsies (>6 months), and C4d-positive patients in early and in later biopsies was different ( P  = 0.028, log–rank test). The adjusted risk ratio of graft failure after Cox proportional hazards multivariate analyses for C4d-positive patients was 3.309 (95% confidence interval, 1.413–6.537; P  = 0.004).
Conclusion:   Patients with C4d deposition had an inferior graft survival, especially with diffused C4d deposition, and later experienced acute rejection. C4d deposition was an independent risk factor for graft survival.     

C4d peritubular capillary staining in chronic allograft nephropathy and transplant glomerulopathy: an uncommon finding

The true incidence of positive C4d staining in the peritubular capillaries of biopsies with chronic allograft nephropathy (CAN) and transplant glomerulopathy (TGP) remains controversial. We retrospectively reviewed all transplant biopsies performed at Saint Louis University Hospital between June 2002 and May 2004. We examined the incidence of positive C4d staining in the peritubular capillaries of biopsy specimens with pure CAN with or without features of TGP. We identified 54 biopsies in 43 patients showing CAN. The average age was 46 ± 13 years. The average creatinine at the time of biopsy was 308 ± 211 μmol/l (3.5 ± 2.4 mg/dl). Twenty (37%) biopsies exhibited features consistent with TGP. Only two biopsies had positive C4d staining in the peritubular capillaries. The C4d positive biopsies were from two different patients; one patient had donor specific antibodies (DSA) against HLA class 1 at the time of biopsy and the other patient had no detectable DSA. None of the TGP biopsies showed peritubular C4d staining. C4d staining of the peritubular capillaries appears to be rare in patients with pure CAN with and without TGP features.     

Renal allograft C4d deposition in Chinese: Hong Kong perspective

Background: Acute rejection constitutes a significant proportion of renal allograft loss. Peritubular capillary deposition of C4d has been recognized as the footprint of humoral alloimmunity and proven to be a sensitive and specific marker for humoral rejection in the appropriate clinical context. Its presence in indication biopsies is the most important independent risk factor for graft failure. Data are, however, scarce among Chinese subjects. Methods: We retrospectively reviewed all renal graft biopsies performed from 1 April 2002 to 31 March 2006 for unexplained acute renal dysfunction or delayed graft function. Renal outcomes were assessed at the time of renal biopsy and at 1 month, 3 months, 6 months and 1 year afterwards. Survival was assessed by Kaplan–Meier analysis. Multivariate analysis was used to determine if C4d positivity is an independent risk factor for poor renal outcome. Results: Fifty‐two biopsies were included, of which 16 were positive for peritubular capillary C4d. Peritubular capillary C4d was associated with lower glomerular filtration rate and higher serum creatinine at 6 and 12 months after renal biopsies. The C4d‐positive group fares worse in terms of death‐censored graft failure, doubling of serum creatinine and reaching 50% of glomerular filtration rate at the end of the study. Peritubular capillary C4d deposition was the only significant risk factor that predicts graft failure in multivariate analysis. Conclusion: Our findings confirmed the independent prognostic value of peritubular capillary C4d staining on renal allograft survival in Chinese.     

急性细胞性排斥伴补体裂解片断C4d沉积对移植肾预后的影响

探讨急性细胞性排斥伴肾小管周围毛细血管补体裂解片断(C4d)沉积对移植肾预后的影响.方法 经病理证实的急性细胞性排斥肾移植患者 145 例,根据病理表现有否肾小管周围毛细血管C4d沉积,将其分为细胞性排斥+C4d阳性组(C4d阳性组)64例,单纯细胞性排斥组(C4d阴性组)81例.比较两组术前一般情况、排斥反应发病情况、抗排斥治疗、移植肾失功率及移植肾存活率.结果两组的术前一般情况比较差异无统计学意义(P>0.05).C4d阳性组的急性细胞性排斥反应发生时间明显早于C4d阴性组,比较差异有统计学意义(P<0.05).两组Banff 分型Ⅰ型与Ⅱ型比例差异有统计学意义(P<0.01).随访期间C4d阳性组有22例(34%)移植肾失功,明显高于C4d阴性组的11例(14%),比较差异有统计学意义(P<0.01).Kaplan-Meier法分析发现C4d阳性组的移植肾存活率明显低于C4d阴性组(P<0.01),移植肾的5年生存率分别为51%、79%.结论 急性细胞性排斥反应伴肾小管周围毛细血管C4d沉积的肾移植患者,术后较早发生排斥反应,抗排斥治疗效果较差,移植肾存活率低.     

Donor-specific antibody in chronic rejection is associated with glomerulopathy, thickening of peritubular capillary basement membrane, but not C4d deposition

Abstract:  The impact of post-transplant donor-specific antibody (DSA) on the development of chronic rejection has been focused recently. The aim of this study was to evaluate the significance of DSA, graft function and pathological factors of chronic rejection. Seventy-three kidney recipients who underwent protocol biopsy were included in the study. The median follow-up period after transplant was 40 months. The presence of anti-HLA antibody (aHLAAb) and DSA was tested using flow beads analysis (FlowPRA®). The patients were divided into a group with DSA, a group with non-donor-specific aHLAAb and a group without aHLAAb. Protocol biopsy specimen were compared for transplant glomerulopathy (cg), vasculopathy (cv), C4d deposition at peritubular capillary (PTC), peritubular capillaritis (ptc score 0–3) and thickening of PTC basement membrane (ptcbm score 0–3) as recently proposed. The presence of DSA was significantly associated with the presence of cg, ptcbm. The group with non-donor-specific aHLAAb had ptcbm but did not have cg. The group without aHLAAb rarely showed ptcbm. The presence of DSA was associated with impaired graft function. C4d was not specific for the patients with DSA. These histopathological markers are useful in the detection of immunological chronic rejection. Early detection by screening tests will be important for treatment before irreversible change occurs.     

用补体裂解片断C4d监测大鼠移植肾慢性排斥反应

目的探讨补体裂解片断C4d在监测大鼠肾移植后慢性排斥反应中的作用与意义。方法以封闭群Wistar大鼠为供者,SD大鼠为受者,建立大鼠肾移植模型。将42只受者随机平均分为2组,A组在肾移植术后10d内给予小剂量环孢素A(5mg·kg-1·d-1)治疗;B组除使用环孢素A外,另给予霉酚酸酯10mg·kg-1·d-1灌胃。术后第3、5和10周观察各组移植肾形态变化及移植肾组织中C4d沉积情况。结果从术后第3周起,A组开始出现轻微慢性排斥反应的病理改变,并随着时间的推移逐渐明显。B组于术后第5周开始出现慢性排斥反应的病理改变,程度轻于A组。术后第3周A组即出现明显C4d沉积,至第10周时沉积已较广泛。B组也有C4d沉积,但沉积程度较A组同时段轻(P<0.05)。结论移植肾组织中C4d的沉积早于慢性排斥反应的病理改变,可作为预测慢性排斥反应的有效指标。     

Monocytes and peritubular capillary C4d deposition in acute renal allograft rejection

BACKGROUND: Peritubular capillary (PTC) deposition of complement split factor C4d in renal allografts has been shown to be closely associated with circulating antidonor antibodies and a marker for relatively poor graft survival. Monocyte/macrophage (MO) infiltration of renal allografts has been shown to adversely affect graft survival. The purpose of this study was to assess whether the two phenomena are related. METHODS: Twenty-three biopsies (from 15 patients) demonstrated diffuse strong staining of PTC for C4d (C4d+ group) and acute tubular injury with or without significant cellular rejection, while 28 biopsies (with acute rejection) but negative for PTC C4d served as controls (C4d- group). RESULTS: The C4d+ group demonstrated significantly greater glomerular and interstitial MO infiltration than did the C4d- group [3.4 +/- 2.0 vs. 0.2 +/- 0.3 MO/glomerulus, P < 0.0001; 12.9 +/- 9.2 vs. 6.5 +/- 5.0 MO/high power field (hpf), P = 0.0030]. Neutrophilic (PMN) infiltration of glomeruli and PTC was also significantly greater in the C4d+ group than in the C4d- one (0.8 +/- 0.6 vs. 0.3 +/- 0.3 PMN/glomerulus, P = 0.0003; 0.9 +/- 0.8 vs. 0.4 +/- 0.3 PTC PMN/hpf, P = 0.0035). CONCLUSION: The results indicate a close association between PTC C4d deposition and MO infiltration, particularly glomerular, and confirm previous observations regarding the correlation of PTC C4d staining and PMN infiltration.     

Peritubular capillary C4d deposition and renal outcome in post-transplant IgA nephropathy

BACKGROUNDS: Immunological staining of the transplanted kidney for C4d in peritubular capillaries (C4d(PTC)) has emerged as a useful method to detect antibody-mediated rejection in situ. In this retrospective study, we evaluated the prevalence of C4d(PTC) deposition in allograft renal biopsies diagnosed of IgA nephropathy (IgAN) and analysed its clinical significance. METHOD: Sixty-six biopsy specimens of post-transplant IgAN, which were obtained to evaluate azotemia and/or heavy proteinuria, were examined by immunohistochemical staining of the paraffin sections with polyclonal antibody for C4d. RESULTS: C4d was stained positively in peritubular capillaries in 16 (24%) of the 66 cases. The C4d(PTC)-negative (n=50) and C4d(PTC)-positive groups (n=16) were not different in recipient gender, age, donor age, type of donor (living vs. cadaveric), interval from transplantation to graft biopsy (41.6+/- 21.8 vs. 48.3+/-26.1 months) and post-biopsy follow-up period (60.3+/-23.3 vs. 56.9+/-25.4 months). During the follow-up period, 12 of 50 (24%) although the incidence of graft failure was not different by the C4d deposition in peritubular capillaries, intervals from renal biopsy to graft failure tended to be shorter in C4d(PTC)-positive cases than C4d(PTC)-negative cases. In Kaplan-Meier analysis, the renal allograft function of the C4d(PTC)-positive group deteriorated more rapidly than that of the C4d(PTC)-negative group (p<0.05). Histologically, the C4d(PTC)-positive group had findings suggestive of acute cellular rejection more commonly than the C4d(PTC)-negative group (p<0.01). CONCLUSIONS: Evidence of humoral rejection, as demonstrated by C4d(PTC) deposition, was concurrently present in significant portions of post-transplant IgAN biopsy specimens and was associated with more rapid deterioration of renal function. These results suggest that C4d(PTC) positivity needs to be determined at the time of biopsy even in cases of post-transplant glomerulonephritis and immunosuppression may need to be modified accordingly.