Behaviour of non-donor specific antibodies during rapid re-synthesis of donor specific HLA antibodies after antibody incompatible renal transplantation

Background: HLA directed antibodies play an important role in acute and chronic allograft rejection. During viral infection of a patient with HLA antibodies, the HLA antibody levels may rise even though there is no new immunization with antigen. However it is not known whether the converse occurs, and whether changes on non-donor specific antibodies are associated with any outcomes following HLA antibody incompatible renal transplantation. Methods: 55 patients, 31 women and 24 men, who underwent HLAi renal transplant in our center from September 2005 to September 2010 were included in the studies. We analysed the data using two different approaches, based on; i) DSA levels and ii) rejection episode post transplant. HLA antibody levels were measured during the early post transplant period and corresponding CMV, VZV and Anti-HBs IgG antibody levels and blood group IgG, IgM and IgA antibodies were quantified. Results: Despite a significant DSA antibody rise no significant non-donor specific HLA antibody, viral or blood group antibody rise was found. In rejection episode analyses, multiple logistic regression modelling showed that change in the DSA was significantly associated with rejection (p = 0.002), even when adjusted for other antibody levels. No other antibody levels were predictive of rejection. Increase in DSA from pre treatment to a post transplant peak of 1000 was equivalent to an increased chance of rejection with an odds ratio of 1.47 (1.08, 2.00). Conclusion: In spite of increases or decreases in the DSA levels, there were no changes in the viral or the blood group antibodies in these patients. Thus the DSA rise is specific in contrast to the viral, blood group or third party antibodies post transplantation. Increases in the DSA post transplant in comparison to pre-treatment are strongly associated with occurrence of rejection

Do we practice what we preach? Dialysis modality choice among healthcare workers in the United Kingdom

Background: In the United Kingdom, over 80% of end‐stage kidney disease patients receive in‐center hemodialysis. We conducted a survey of UK renal healthcare workers on their preferred dialysis modality if they needed dialysis themselves. Methods: An anonymized online survey was disseminated to all renal healthcare workers in the United Kingdom. We asked “Assume you are an otherwise well 40‐year‐old (and, separately, 75‐year‐old) person approaching end stage kidney disease, you have no living kidney donor options at present. There are no contraindications to any dialysis options. Which dialysis therapy would you choose?” We also asked about factors influencing their choice. Results: 858 individuals with a median age of 44.3 years responded. 70.2% were female, 37.4% doctors, and 31.1% were senior nurses. There was a preference for peritoneal dialysis over in‐center hemodialysis (50.47% v. 6.18%; p < 0.001 for 40‐year‐old and 49.18% v. 17.83%; p < 0.001 for 75‐year‐old assumption) and home hemodialysis (50.47% v. 39.28%; p < 0.001 for 40‐year‐old and 49.18% v. 18.41% for 75‐year‐old assumption). There was a preference for home hemodialysis over in‐center hemodialysis for 40‐year‐old (39.28% v. 6.18%; p < 0.001) but not for 75‐year‐old. On logistic regression, senior doctors were more likely to opt for PD when compared to nurses. Nurses, allied healthcare professionals, and those of Asian/British Asian ethnicity were more likely to choose in‐center hemodialysis. Conclusions: Most healthcare workers in renal medicine would choose home‐based treatment for themselves although the majority of end‐stage kidney disease patients receive in‐center hemodialysis in the United Kingdom; the reasons for the discrepancy need to be explored

Donor specific antibodies and the complement system in HLA-antibody incompatible renal transplantation

Despite advances in medical science, dialysis treatment for end stage renal disease remains fraught with complications and severely limits the quality and longevity of life in these patients. Renal transplantation allows for an enhanced length and quality of life. Unfortunately the demand for kidneys outstrips the supply and nephrologists have taken to performing transplantation in conditions that were previously thought impossible. Human leucocyte antigen (HLA) antibody incompatible transplantation, a process of transplanting kidneys into recipients who have antibodies against HLA antigen on the donor kidney, has recently become an acceptable mode of transplanting patients who would have previously died whilst on dialysis. Although increasingly successful, the Achilles’ heel of this form of transplantation remains acute antibody mediated rejection (AMR), a particularly severe form of rejection. It is generally accepted that the complement system is intricately involved in the process of acute AMR and, indeed, C4d, a split product of complement factor C4, when detected on renal biopsies in the correct context, is considered by the BANFF classification (an internationally accepted method of classifying renal transplant rejection) to be a hallmark feature of acute AMR. The sensitivity and specificity of this test, however, is increasingly debated and requires an interventional diagnostic test that is not without risk. A “blood” test to detect or predict the onset of acute AMR is not available. In addition, although the complement system is known to be involved in acute AMR, characterisation of the three complement pathways and the degree of their systemic activation has not been fully described. Although the liver is the main source of complement factors in the body, other organs such as the kidney, are capable of synthesizing complement. It is unknown whether the complement factors involved in acute AMR following renal transplantation are of systemic or local origin. It is also not known which renal cell, if any, is responsible for this. Importantly, the first cells to encounter antibodies against antigen on their surfaces, the renal microvascular endothelial cells, have not so far been shown to be able to produce complement factors. This thesis briefly examines changes in antibody levels during the process of HLA antibody incompatible transplantation, histological features associated with subsequent graft dysfunction and possible serum markers (soluble CD27 and Cd30) that could indicate onset of AMR. Whilst anti-HLA antibody monitoring was found to be useful in the management of patients it was not possible to use levels to predict rejection or accommodation of the graft. No correlation was found between soluble factors CD27 and CD30 and AMR. The thesis then examines the effect of HLA antibody incompatible renal transplantation on the complement pathways and on the levels of complement factors C3a and C4a. There was no systemic pathway activation in the presence of rejection. Systemic levels of C3a and C4a did not rise with a simultaneous increased level of HLA antibodies or with rejection episodes. Indeed, in patients who did not have an episode of rejection and in those with rejection but no evidence of C4d on renal biopsy, mean C4a levels were significantly lower at 4-6 weeks when compared to those who did have C4d-postive AMR. This points to a role for inhibitory mechanisms in these patients. The thesis also demonstrates the ability of microvascular endothelial cells (including of glomerular origin for the first time) to produce complement C4 on stimulation with gamma interferon and with antibodies against the cell HLA type. Finally, the thesis briefly examines the possible use of a complement inhibitor in the treatment of AMR

Regional variations in nephrology trainee confidence with clinical skills may relate to the availability of local training opportunities in the UK: results from a national survey.

BACKGROUND The United Kingdom offers a standardised training program for nephrology fellows. However, local training opportunities vary resulting in mismatches between trainee interests and accessible opportunities. This may impact trainee confidence, satisfaction, and future service provision. METHODS A survey assessing confidence with key procedures and sub-specialities was disseminated. Associations with region of training were probed using Chi square tests, with significance set at p < 0.0008 following a Bonferroni correction. Results were compared to trainee views on available opportunities for development. RESULTS 139 responses were received (32% response rate, demographics representative of the UK nephrology trainee cohort). Procedural independence varied from 98% for temporary femoral vascular catheters to 5% for peritoneal dialysis catheters (PDIs). Independence with inserting tunnelled vascular catheters varied with region (p < 0.0001). Trainees expressed a desire for formal training in kidney ultrasound scanning and PDIs, corresponding with procedures they had least opportunity to become independent with. Trainees felt least confident managing kidney disease in pregnancy. Suggestions for improving training included protected time for garnering sub-speciality knowledge, developing procedural skills and for experiencing practice in other nephrology units. CONCLUSIONS A mismatch between trainee interests and professional development opportunities exists, which may threaten trainee autonomy and impact patient care particularly with regards to peritoneal dialysis. Provisions to facilitate trainee directed development need to be made while balancing the rigors of service provision. Such measures could prove critical to promoting trainee well-being and preventing attrition within the nephrology workforce

Cryofiltration in the treatment of cryoglobulinemia and HLA antibody-incompatible transplantation

Cryofiltration is a technique in which plasma is separated from blood and chilled, leading to the formation of “cryogel”, a composite of heparin, fibronectin, fibrinogen, immunoglobulins, and other proteins. This is retained by further filtration and plasma is returned to the patient. There may be a role for cryofiltration in the treatment of cryoglobulinemia or where the application of other forms of plasmapheresis or immunoadsorption is limited. Five patients received six courses of cryofiltration. Two patients had cryoglobulinemia and three were treated before HLA antibody-incompatible renal transplantation. The treatment was associated with few adverse effects, and it was possible to treat up to 120 mL/kg plasma per session. There was a good clinical response in four patients. One patient was switched back to double filtration plasmapheresis (DFPP) because cryofiltration seemed to remove HLA antibodies less effectively, but the other two transplants have excellent function. In the cryoglobulinemia patients there was excellent clearance of cryoglobulins during each treatment (mean decrease of 78.2 (SD 14.1)% per treatment). Compared with DFPP, fewer immunoglobulins were removed and the mean percentage reductions in immunoglobulin G per treatment were 36.0 (4.0)% for cryoglobulinemia and 59.2 (2.5)% for DFPP (P < 0.01), with respective mean plasma volumes of 64.2 (10.3) and 71.1 (6.8) mL/kg treated. Cryofiltration offers a treatment choice in patients with cryoglobulinemia and in those who may not be able to tolerate high-volume DFPP. The technique used in the patients described here was less effective than DFPP; however, use of an alternative fractionator and treatment of higher plasma volumes may enhance the efficiency of cryofiltration

Rises and falls in donor-specific and third-party HLA antibody levels after antibody incompatible transplantation

Background. After human leukocyte antigen (HLA) antibody-incompatible transplantation, donor specific and third party HLA antibodies may be found, and their levels fall in a donor-specific manner during the first month. However, these changes have not been previously described in detail. Methods. Donor-specific HLA antibody (DSA) and third-party HLA antibody (TPA) levels were measured using the microbead method in 44 presensitized patients who had renal transplantation. Results. DSA+TPA fell in the first 4 days after transplantation, and greater falls in DSA indicated absorption by the graft. This occurred for class I (57.8% fall compared with 20.2% for TPA, P<0.0005), HLA DR (63.0% vs. 24.3%, P<0.0004), and for HLA DP/DQ/DRB3-4 (34% vs. 17.5%, P=0.014). Peak DSA levels occurred at a mean of 13 days posttransplant, and they were higher than pretreatment in 25 (57%) patients and lower in 19 (43%) patients (P=ns). The risk of rejection was associated with peak DSA levels; 15 of 25 (60%) patients with DSA at median fluorescence intensity (MFI) more than 70000 experienced rejection, compared with 4 of 7 (57%) patients with peak DSA MFI 2000 to 70000, and 2 of 12 (17%) patients with peak DSA MFI less than 20000 (P<0.02). DSA levels subsequently fell in a donor specific manner compared to TPA. Conclusion. DSA levels may change markedly in the first month after antibody incompatible transplantation, and the risk of rejection was associated with higher pretreatment and peak levels

The histological development of acute antibody-mediated rejection in HLA antibody-incompatible renal transplantation

Background. The aim of this study was to examine the development of acute antibody-mediated rejection in HLA antibody-incompatible renal transplantation in relation to the Banff 07 histological classification. Methods. Renal biopsies were scored using the Banff 07 diagnostic criteria, and paraffin-embedded sections were stained with the pan-leucocyte marker CD45. Results. Thirty-six patients had 72 renal biopsies. In biopsies performed 30 min after graft reperfusion, the mean number of CD45+ cells per glomerulus was higher than in control grafts (P<0.04) and was associated with the donor-specific antibody (DSA) level at transplantation measured by microbeads (P<0.01), and eight out of nine patients with greater than five CD45+ cells per glomerulus had early post-transplant rejection or oliguria, compared to 11 out of 20 with less than five cells per glomerulus (P<0.01). In the first 10 days post-transplant, although peritubular capillary (PTC) leucocyte margination grade 3 and C4d deposition were specific for rejection, their sensitivities were low. PTC C4d staining was only seen in two out of 11 biopsies taken in the first 5 days after transplant, even in the presence of rejection, but was present in the majority of later biopsies with rejection. In biopsies stained for CD3, CD68 and CD20, it was notable that CD20+ cells were not seen during acute rejection, the infiltrates comprising CD3+ and CD68+ leucocytes. Conclusions. Glomerular margination of leucocytes occurred early after transplantation and was associated with DSA level and early graft dysfunction. The Banff 07 PTC margination scoring system was easy to apply, especially when CD45 staining was used, and PTC margination grade 3 was always associated with clinical rejection

Double filtration plasmapheresis in antibody-incompatible kidney transplantation

Double filtration plasmapheresis (DFPP) was used in preference to plasma exchange in our program of antibody-incompatible transplantation, to treat higher volumes of plasma. Forty-two patients had 259 sessions of DFPP, 201 pre-transplant and 58 post-transplant. At the first treatment session, the mean plasma volume treated was 3.81 L (range 3-6 L), 55.5 mL/kg (range 36.2-83.6 mL/kg). Serum IgG fell by mean 59.4% (SD 10.2%), and IgM by 69.3% (SD 16.1%). Nine patients did not require increases in plasma volumes treated, and six did not tolerate higher plasma volumes. In the remaining patients, the mean maximum plasma volume treated pre-transplant was 6.67 L (range 4-15 L), 96.1 mL/kg (range 60.2-208.9 mL/kg). The complement dependent cytotoxic crossmatch was positive in 14 cases pre-treatment, and remained positive in six (42.8%) cases. The flow cytometric crossmatch was positive in 29 cases pre-treatment, and in 21 (72.4%) after DFPP. Post-transplant, DFPP was ineffective at reducing donor specific antibody levels during periods of rapid donor specific antibody synthesis. Post-transplant, the one year graft survival rate was 94%, although there was a high rate of early rejection. In summary, DFPP enabled the treatment of plasma volumes that were almost double those that would have been feasible with plasma exchange. Despite this, most patients were transplanted with a positive crossmatch, and DFPP post-transplant was unable to control rising antibody levels