Human Immunology 75 (2014) 462–465
Contents lists available at ScienceDirect
www.ashi-hla.org
journal homepage: www.elsevier.com/locate/humimm
Rapid Communication
Late antibody-mediated rejection by de novo donor HLA-DP-specific antibody after renal transplantation: A case report Pietro E. Cippà a, Ariana Gaspert b, Christoph Etter a, Zehra Guenduez c, Sylvie Ferrari-Lacraz d, Barbara Rüsi c, Thomas Fehr a,⇑ a
Division of Nephrology, University Hospital Zurich, Switzerland Institute of Surgical Pathology, University Hospital Zurich, Switzerland Interdisciplinary HLA Typing Laboratory, University Hospital Zurich, Switzerland d Swiss National Reference Laboratory for Histocompatibility, Geneva University Hospital, Switzerland b c
a r t i c l e
i n f o
Article history: Received 4 July 2013 Accepted 4 February 2014 Available online 12 February 2014
a b s t r a c t The role of donor HLA-DP-specific antibodies after renal transplantation is controversial, and only preformed HLA-DP-specific antibodies have been shown to mediate rejection. Here we present a case of late humoral rejection mediated by de novo donor HLA-DP-specific antibodies in a non-sensitized recipient. This unique case demonstrates the pathogenic role of de novo anti-DP antibodies and suggests that HLA-DP matching might be relevant for renal transplantation. Ó 2014 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.
1. Introduction Alloantibodies are involved in hyperacute, acute and chronic allograft rejection, but not all HLA alloantibodies are generally considered pathogenic [1,2]. Particularly, the role of HLA-DP mismatches and of anti-DP antibodies is controversial [3]. Several case reports demonstrated a role for donor HLA-DP-specific antibodies in antibody-mediated rejection (AMR) in sensitized recipients [4–6], and the presence of pre-transplant donor HLADP-specific antibodies correlated with the incidence of acute rejection episodes and with a reduced graft function [7–10]. However, the pathogenicity of de novo HLA-DP antibodies in previously non-sensitized recipients is unclear. Here, we report a case of de novo anti-HLA-DP mediated AMR following renal transplantation.
2. Case description A 60-year-old Caucasian male with end-stage renal disease of unknown origin received a first kidney allograft from a deceased donor with a complete HLA class II match apart of a single mismatch in the HLA-DP locus (Table 1). Pre-transplant screening by Abbreviations: AMR, antibody-mediated-rejection; eGFR, estimated glomerular filtration rate; MFI, mean fluorescence intensity. ⇑ Corresponding author. Address: Division of Nephrology, University Hospital Zurich, Rämistrasse 100, 8091 Zurich, Switzerland. E-mail address: [email protected] (T. Fehr).
Luminex single antigen beads was negative for anti-HLA class I & II antibodies. Donor and recipient were cytomegalovirus seronegative. The patient received induction therapy with basiliximab, followed by tacrolimus, mycophenolate mofetil and prednisone. The postoperative graft function was good with an eGFR of 76 ml/min (CKD-EPI) 1 month after transplantation. Graft biopsy 2 years after transplantation did not show any sign for rejection, and therefore prednisone was withdrawn. Three and a half years after transplantation proteinuria and a significant deterioration of graft function were registered (Fig. 1). Kidney biopsy demonstrated chronic active AMR with diffuse C4d positivity in peritubular capillaries, transplant glomerulopathy, transplant glomerulitis, peritubular capillaritis and calcineurin inhibitor – arteriolopathy (Fig. 2). Anti-HLA antibody screening by Luminex technology did not detect antibodies specific for HLA class I, and we did not find antibodies against MHC class I-related chain A and B (MICA/MICB) or angiotensin II Type 1 receptor. In contrast, anti-HLA class II turned positive. Further specification by Luminex single antigen bead analysis revealed a broad HLA-DP sensitization, with a donor-specific antiHLA-DP10 antibody of a maximal MFI 1976 (Table 1). A retrospectively performed anti-C1q luminex assay was negative, indicating that the de novo anti-DP antibody was not complement fixing. The patient was treated with intravenous methylprednisolone and 5 sessions of plasma exchange. Transplant biopsy one month after initial evaluation showed persisting chronic active AMR with focal positivity for C4d in peritubular capillaries, transplant glomerulopathy and transplant glomerulitis. Donor-specific
http://dx.doi.org/10.1016/j.humimm.2014.02.008 0198-8859/Ó 2014 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.
P.E. Cippà et al. / Human Immunology 75 (2014) 462–465
463
Table 1 Recipient and donor HLA-typing are reported on the left side, single-antigen anti-HLA antibodies detected 3 years and 8 month after transplantation on the right side. Donor specific anti-HLA-DP10 is indicated in bold. HLA-typing Recipient A2, A29 B44(12), B18 DR1, DR15(2) DQB1⁄05, DQB1⁄06 DPA1⁄01:03, DPB1⁄02:01 = DP2 DPA1⁄01:03, DPB1⁄04:01 = DP4
Anti-HLA Donor A2, A24(9) B62(15), B60(40) DR1, DR15(2) DQB1⁄05, DQB1⁄06 DPA1⁄02:01, DPB1⁄10:01 = DP10 DPA1⁄01:03, DPB1⁄04:01 = DP4
3 years and 8 months post-tpl Negative Negative Negative Negative DPA1⁄02:01, DPB1⁄09:01 = DP9 (MFI 3033) DPA1⁄02:01, DPB1⁄14:01 = DP14 (MFI 2436) DPA1⁄02:01, DPB1⁄01:01 = DP1 (MFI 2329) DPA1⁄02:01, DPB1⁄10:01 = DP10 (MFI 1976) DPA1⁄01:05, DPB1⁄11:01 = DP11 (MFI 1741) DPA1⁄02:01, DPB1⁄06:01 = DP6 (MFI 1741) DPA1⁄02:01, DPB1⁄03:01 = DP3 (MFI 1642) DPA1⁄02:01, DPB1⁄17:01 = DP17 (MFI 1617) DPA1⁄01:03, DPB1⁄03:01 = DP3 (MFI 1421) DPA1⁄01:03, DPB1⁄01:01 = DP1 (MFI 1416) DPA1⁄01:05, DPB1⁄03:01 = DP3 (MFI 1236) DPA1⁄01:03, DPB1⁄11:01 = DP11 (MFI 1082) DPA1⁄02:01, DPB1⁄05:01 = DP5 (MFI 986) DPA1⁄02:01, DPB1⁄18:01 = DP18 (MFI 802) DPA1⁄02:01, DPB1⁄13:01 = DP13 (MFI 510)
Fig. 1. Summary of the patient’s clinical history and concomitant HLA antibody determinations: (upper panel) graft function is indicated by serum creatinine concentration, protenuria was determined by protein–creatinine ratio from morning spot urine. PEX: plasma exchange. DSA: donor specific antibody. (lower panel) Anti-HLA antibody screening is indicated by ratio of patient sample versus negative control serum (Luminex mix, left x-axis), donor-specific anti-HLA DP10 antibody (DSA) is indicated by mean fluorescence intensity values (Luminex single antigen bead assay; MFI; right x-axis).
anti-HLA-DP10 antibodies were markedly reduced (MFI 628). The patient was treated with two additional cycles of high-dose methylprednisolone, rituximab and 6 sessions of plasma exchange. Allograft function slowly improved and remained stable with an eGFR of 35 ml/min in the following months. A repeat biopsy 6 months later showed transplant glomerulopathy and transplant glomerulitis without C4d reactivity in peritubular capillaries (Fig. 3). Donor-specific antibodies now turned negative. One year after first diagnosis of AMR the patient developed several infectious complications including atypical mycobacteriosis (Mycobacterium kansasii/Mycobacterium gastri), which required withdrawal from immunosuppression and eventually transplant nephrectomy. No anti-donor-HLA antibody other than the DP antibody was detected throughout the posttransplant period.
3. Methods Recipient and donor HLA-typing was done by serology and polymerase chain reaction with sequence-specific primers (PCRSSP). Anti-HLA antibody screening assay was performed with LABScreen mixed assay (LSM12, OneLambda, Canoga Park, CA). This assay contains a panel of color-coded microbeads coated with multiple HLA antigens to identify class I or II anti-HLA IgG antibodies and was performed according to the manufacturer’s instructions. Single-antigen bead assay was performed using a high-definition LABScreen single antigen assay (OneLambda). Serum was added
464
P.E. Cippà et al. / Human Immunology 75 (2014) 462–465
Fig. 2. Kidney biopsy three and a half years after transplantation. (A and B) Transplant glomerulitis with mononuclear cells in glomerular capillaries and transplant glomerulopathy with glomerular double contours (arrows); (A) periodic acid-Schiff stain, original magnification 140; (B) methenamine silver stain, original magnification 140). (C) Peritubular capillaritis with mononuclear cells in peritubular capillaries (CD31 immunohistochemistry, original magnification 120). (D) Thickening and lamellation of the glomerular basement membrane (electron microscopy, original magnification 2000).
Fig. 3. Kidney biopsy 4 years after transplantation. (A and B) Transplant glomerulitis and transplant glomerulopathy with progressive thickening and splitting of the glomerular basement membrane (A) periodic acid-Schiff stain, original magnification 120; (B) methenamine silver stain, original magnification 200.
to class I panel (LS1A01, LAT1-HD) or class II panel (LS2A01, LAT2HD) microbeads, and processed according to the manufacturer’s instructions. Test interpretation was performed using HLA Visual software (OneLambda Inc.) on the LABScan100 flow cytometer (Luminex Inc., Austin, TX) [11]. Anti-C1q Luminex assay was performed using the C1qScreen technology according to the manufacturer’s protocol (OneLambda Inc.). Angiotensin II Type 1 receptor antibodies were measured by ELISA according to the protocol of OneLamba Inc. Kidney biopsies were fixed in 4% neutral buffered formalin, embedded in paraffin and sectioned according to the standard processing of transplant kidney biopsies at the Institute of Surgical Pathology. Serial sections were cut and stained with hematoxylin and eosin, PAS (periodic acid-Schiff), methenamine silver, elastic van Gieson, and acid fuchsin orange-G. C4d immunofluorescence was performed routinely on frozen kidney biopsies [12]. 4. Discussion The clinical relevance of the HLA-DP locus for prognosis after renal transplantation is controversial: the pathogenic role of pre-
formed HLA-DP-specific antibodies in acute and chronic AMR has been shown in several case reports [4–6], and HLA-DP-mismatches are known to influence outcome after re-transplantation [9,10]. In contrast, HLA-DP mismatch was not relevant for graft survival in first deceased-donor transplants [9]. To our knowledge, this is the first reported case of AMR mediated by isolated de novo donor-specific anti-HLA-DP antibodies. The pathogenic role of HLADP antibodies is suggested by the absence of anti-HLA class I and anti-HLA-DR and HLA-DQ antibodies throughout the post-transplant period, by the absence of mismatches in the HLA-DR and DQ loci (as determined on the serological level), and by the de novo HLA-DP sensitization. In the current study the antibodies were reactive towards several HLA-DPB1 alleles that all share the DEAV epitope in the hypervariable region F (position 84–87), whereas the recipient HLA-DPB1 alleles express a GGPM epitope in the same region [3]. Therefore, the pathogenic antibody is likely to bind to this epitope of the HLA-DP molecule. Although tests for anti-MICA, anti-MICB and anti-angiotensin II type 1 receptor antibodies were negative, we cannot formally exclude that other non-HLA antibodies might play a role in this case, but this possibility is rather unlikely.
P.E. Cippà et al. / Human Immunology 75 (2014) 462–465
This case of AMR is unique because of the particular HLA-mismatch and because of the unexpected absence of anti-MHC class I reactivity despite three mismatches in the HLA-A and HLA-B locus, but it has a particular immunological relevance, since it demonstrates for the first time that a single HLA-DP mismatch might be sufficient to induce de novo donor-specific antibodies leading to acute and chronic AMR. The other HLA class II molecules DR and DQ seem to be more immunogenic than HLA-DP and might therefore mask the role of HLA-DP mismatches in larger studies [9]. However, the case presented here demonstrates the clinical relevance of HLA-DP. HLA-DP typing and matching should be considered for living donation and in particular for patients with preformed anti-DP antibodies to improve outcome after renal transplantation. References [1] Colvin RB, Smith RN. Antibody-mediated organ-allograft rejection. Nat Rev Immunol 2005;5:807. [2] Fehr T, Gaspert A. Antibody-mediated kidney allograft rejection: therapeutic options and their experimental rationale. Transpl Int 2012;25:623. [3] Billen EV, Christiaans MH, Doxiadis II, Voorter CE, van den Berg-Loonen EM. HLA-DP antibodies before and after renal transplantation. Tissue Antigens 2010;75:278. [4] Thaunat O, Hanf W, Dubois V, McGregor B, Perrat G, Chauvet C, et al. Chronic humoral rejection mediated by anti-HLA-DP alloantibodies: insights into the
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
465
role of epitope sharing in donor-specific and non-donor specific alloantibodies generation. Transpl Immunol 2009;20:209. Goral S, Prak EL, Kearns J, Bloom RD, Pierce E, Doyle A, et al. Preformed donordirected anti-HLA-DP antibodies may be an impediment to successful kidney transplantation. Nephrol Dial Transplant 2008;23:390. Jolly EC, Key T, Rasheed H, Morgan H, Butler A, Pritchard N, et al. Preformed donor HLA-DP-specific antibodies mediate acute and chronic antibodymediated rejection following renal transplantation. Am J Transplant 2012;12:2845. Qiu J, Cai J, Terasaki PI, El-Awar N, Lee JH. Detection of antibodies to HLA-DP in renal transplant recipients using single antigen beads. Transplant 2005;80:1511. Samaniego M, Mezrich J, Torrealba J, Lorentzen D, Schadde E, Djamali A, et al. C4d-positive acute antibody-mediated rejection due to anti-HLA-DP antibody: a tale of one patient and a review of the University of Wisconsin experience. Clin Transpl 2006:503. Mytilineos J, Deufel A, Opelz G. Clinical relevance of HLA-DPB locus matching for cadaver kidney retransplants: a report of the collaborative transplant study. Transplant 1997;63:1351. Couzi L, Araujo C, Guidicelli G, Bachelet T, Moreau K, Morel D, et al. Interpretation of positive flow cytometric crossmatch in the era of the single-antigen bead assay. Transplant 2011;91:527. Riethmuller S, Ferrari-Lacraz S, Muller MK, Raptis DA, Hadaya K, Rusi B, et al. Donor-specific antibody levels and three generations of crossmatches to predict antibody-mediated rejection in kidney transplantation. Transplant 2010;90:160. Varga Z, Gaspert A, Behnke S, von Teichman A, Fritzsche F, Fehr T. Tubular and endothelial chimerism in renal allografts using fluorescence and chromogenic in situ hybridization (FISH, CISH) technology. Pathol Int 2012;62:254.
Contents lists available at ScienceDirect
www.ashi-hla.org
journal homepage: www.elsevier.com/locate/humimm
Rapid Communication
Late antibody-mediated rejection by de novo donor HLA-DP-specific antibody after renal transplantation: A case report Pietro E. Cippà a, Ariana Gaspert b, Christoph Etter a, Zehra Guenduez c, Sylvie Ferrari-Lacraz d, Barbara Rüsi c, Thomas Fehr a,⇑ a
Division of Nephrology, University Hospital Zurich, Switzerland Institute of Surgical Pathology, University Hospital Zurich, Switzerland Interdisciplinary HLA Typing Laboratory, University Hospital Zurich, Switzerland d Swiss National Reference Laboratory for Histocompatibility, Geneva University Hospital, Switzerland b c
a r t i c l e
i n f o
Article history: Received 4 July 2013 Accepted 4 February 2014 Available online 12 February 2014
a b s t r a c t The role of donor HLA-DP-specific antibodies after renal transplantation is controversial, and only preformed HLA-DP-specific antibodies have been shown to mediate rejection. Here we present a case of late humoral rejection mediated by de novo donor HLA-DP-specific antibodies in a non-sensitized recipient. This unique case demonstrates the pathogenic role of de novo anti-DP antibodies and suggests that HLA-DP matching might be relevant for renal transplantation. Ó 2014 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.
1. Introduction Alloantibodies are involved in hyperacute, acute and chronic allograft rejection, but not all HLA alloantibodies are generally considered pathogenic [1,2]. Particularly, the role of HLA-DP mismatches and of anti-DP antibodies is controversial [3]. Several case reports demonstrated a role for donor HLA-DP-specific antibodies in antibody-mediated rejection (AMR) in sensitized recipients [4–6], and the presence of pre-transplant donor HLADP-specific antibodies correlated with the incidence of acute rejection episodes and with a reduced graft function [7–10]. However, the pathogenicity of de novo HLA-DP antibodies in previously non-sensitized recipients is unclear. Here, we report a case of de novo anti-HLA-DP mediated AMR following renal transplantation.
2. Case description A 60-year-old Caucasian male with end-stage renal disease of unknown origin received a first kidney allograft from a deceased donor with a complete HLA class II match apart of a single mismatch in the HLA-DP locus (Table 1). Pre-transplant screening by Abbreviations: AMR, antibody-mediated-rejection; eGFR, estimated glomerular filtration rate; MFI, mean fluorescence intensity. ⇑ Corresponding author. Address: Division of Nephrology, University Hospital Zurich, Rämistrasse 100, 8091 Zurich, Switzerland. E-mail address: [email protected] (T. Fehr).
Luminex single antigen beads was negative for anti-HLA class I & II antibodies. Donor and recipient were cytomegalovirus seronegative. The patient received induction therapy with basiliximab, followed by tacrolimus, mycophenolate mofetil and prednisone. The postoperative graft function was good with an eGFR of 76 ml/min (CKD-EPI) 1 month after transplantation. Graft biopsy 2 years after transplantation did not show any sign for rejection, and therefore prednisone was withdrawn. Three and a half years after transplantation proteinuria and a significant deterioration of graft function were registered (Fig. 1). Kidney biopsy demonstrated chronic active AMR with diffuse C4d positivity in peritubular capillaries, transplant glomerulopathy, transplant glomerulitis, peritubular capillaritis and calcineurin inhibitor – arteriolopathy (Fig. 2). Anti-HLA antibody screening by Luminex technology did not detect antibodies specific for HLA class I, and we did not find antibodies against MHC class I-related chain A and B (MICA/MICB) or angiotensin II Type 1 receptor. In contrast, anti-HLA class II turned positive. Further specification by Luminex single antigen bead analysis revealed a broad HLA-DP sensitization, with a donor-specific antiHLA-DP10 antibody of a maximal MFI 1976 (Table 1). A retrospectively performed anti-C1q luminex assay was negative, indicating that the de novo anti-DP antibody was not complement fixing. The patient was treated with intravenous methylprednisolone and 5 sessions of plasma exchange. Transplant biopsy one month after initial evaluation showed persisting chronic active AMR with focal positivity for C4d in peritubular capillaries, transplant glomerulopathy and transplant glomerulitis. Donor-specific
http://dx.doi.org/10.1016/j.humimm.2014.02.008 0198-8859/Ó 2014 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.
P.E. Cippà et al. / Human Immunology 75 (2014) 462–465
463
Table 1 Recipient and donor HLA-typing are reported on the left side, single-antigen anti-HLA antibodies detected 3 years and 8 month after transplantation on the right side. Donor specific anti-HLA-DP10 is indicated in bold. HLA-typing Recipient A2, A29 B44(12), B18 DR1, DR15(2) DQB1⁄05, DQB1⁄06 DPA1⁄01:03, DPB1⁄02:01 = DP2 DPA1⁄01:03, DPB1⁄04:01 = DP4
Anti-HLA Donor A2, A24(9) B62(15), B60(40) DR1, DR15(2) DQB1⁄05, DQB1⁄06 DPA1⁄02:01, DPB1⁄10:01 = DP10 DPA1⁄01:03, DPB1⁄04:01 = DP4
3 years and 8 months post-tpl Negative Negative Negative Negative DPA1⁄02:01, DPB1⁄09:01 = DP9 (MFI 3033) DPA1⁄02:01, DPB1⁄14:01 = DP14 (MFI 2436) DPA1⁄02:01, DPB1⁄01:01 = DP1 (MFI 2329) DPA1⁄02:01, DPB1⁄10:01 = DP10 (MFI 1976) DPA1⁄01:05, DPB1⁄11:01 = DP11 (MFI 1741) DPA1⁄02:01, DPB1⁄06:01 = DP6 (MFI 1741) DPA1⁄02:01, DPB1⁄03:01 = DP3 (MFI 1642) DPA1⁄02:01, DPB1⁄17:01 = DP17 (MFI 1617) DPA1⁄01:03, DPB1⁄03:01 = DP3 (MFI 1421) DPA1⁄01:03, DPB1⁄01:01 = DP1 (MFI 1416) DPA1⁄01:05, DPB1⁄03:01 = DP3 (MFI 1236) DPA1⁄01:03, DPB1⁄11:01 = DP11 (MFI 1082) DPA1⁄02:01, DPB1⁄05:01 = DP5 (MFI 986) DPA1⁄02:01, DPB1⁄18:01 = DP18 (MFI 802) DPA1⁄02:01, DPB1⁄13:01 = DP13 (MFI 510)
Fig. 1. Summary of the patient’s clinical history and concomitant HLA antibody determinations: (upper panel) graft function is indicated by serum creatinine concentration, protenuria was determined by protein–creatinine ratio from morning spot urine. PEX: plasma exchange. DSA: donor specific antibody. (lower panel) Anti-HLA antibody screening is indicated by ratio of patient sample versus negative control serum (Luminex mix, left x-axis), donor-specific anti-HLA DP10 antibody (DSA) is indicated by mean fluorescence intensity values (Luminex single antigen bead assay; MFI; right x-axis).
anti-HLA-DP10 antibodies were markedly reduced (MFI 628). The patient was treated with two additional cycles of high-dose methylprednisolone, rituximab and 6 sessions of plasma exchange. Allograft function slowly improved and remained stable with an eGFR of 35 ml/min in the following months. A repeat biopsy 6 months later showed transplant glomerulopathy and transplant glomerulitis without C4d reactivity in peritubular capillaries (Fig. 3). Donor-specific antibodies now turned negative. One year after first diagnosis of AMR the patient developed several infectious complications including atypical mycobacteriosis (Mycobacterium kansasii/Mycobacterium gastri), which required withdrawal from immunosuppression and eventually transplant nephrectomy. No anti-donor-HLA antibody other than the DP antibody was detected throughout the posttransplant period.
3. Methods Recipient and donor HLA-typing was done by serology and polymerase chain reaction with sequence-specific primers (PCRSSP). Anti-HLA antibody screening assay was performed with LABScreen mixed assay (LSM12, OneLambda, Canoga Park, CA). This assay contains a panel of color-coded microbeads coated with multiple HLA antigens to identify class I or II anti-HLA IgG antibodies and was performed according to the manufacturer’s instructions. Single-antigen bead assay was performed using a high-definition LABScreen single antigen assay (OneLambda). Serum was added
464
P.E. Cippà et al. / Human Immunology 75 (2014) 462–465
Fig. 2. Kidney biopsy three and a half years after transplantation. (A and B) Transplant glomerulitis with mononuclear cells in glomerular capillaries and transplant glomerulopathy with glomerular double contours (arrows); (A) periodic acid-Schiff stain, original magnification 140; (B) methenamine silver stain, original magnification 140). (C) Peritubular capillaritis with mononuclear cells in peritubular capillaries (CD31 immunohistochemistry, original magnification 120). (D) Thickening and lamellation of the glomerular basement membrane (electron microscopy, original magnification 2000).
Fig. 3. Kidney biopsy 4 years after transplantation. (A and B) Transplant glomerulitis and transplant glomerulopathy with progressive thickening and splitting of the glomerular basement membrane (A) periodic acid-Schiff stain, original magnification 120; (B) methenamine silver stain, original magnification 200.
to class I panel (LS1A01, LAT1-HD) or class II panel (LS2A01, LAT2HD) microbeads, and processed according to the manufacturer’s instructions. Test interpretation was performed using HLA Visual software (OneLambda Inc.) on the LABScan100 flow cytometer (Luminex Inc., Austin, TX) [11]. Anti-C1q Luminex assay was performed using the C1qScreen technology according to the manufacturer’s protocol (OneLambda Inc.). Angiotensin II Type 1 receptor antibodies were measured by ELISA according to the protocol of OneLamba Inc. Kidney biopsies were fixed in 4% neutral buffered formalin, embedded in paraffin and sectioned according to the standard processing of transplant kidney biopsies at the Institute of Surgical Pathology. Serial sections were cut and stained with hematoxylin and eosin, PAS (periodic acid-Schiff), methenamine silver, elastic van Gieson, and acid fuchsin orange-G. C4d immunofluorescence was performed routinely on frozen kidney biopsies [12]. 4. Discussion The clinical relevance of the HLA-DP locus for prognosis after renal transplantation is controversial: the pathogenic role of pre-
formed HLA-DP-specific antibodies in acute and chronic AMR has been shown in several case reports [4–6], and HLA-DP-mismatches are known to influence outcome after re-transplantation [9,10]. In contrast, HLA-DP mismatch was not relevant for graft survival in first deceased-donor transplants [9]. To our knowledge, this is the first reported case of AMR mediated by isolated de novo donor-specific anti-HLA-DP antibodies. The pathogenic role of HLADP antibodies is suggested by the absence of anti-HLA class I and anti-HLA-DR and HLA-DQ antibodies throughout the post-transplant period, by the absence of mismatches in the HLA-DR and DQ loci (as determined on the serological level), and by the de novo HLA-DP sensitization. In the current study the antibodies were reactive towards several HLA-DPB1 alleles that all share the DEAV epitope in the hypervariable region F (position 84–87), whereas the recipient HLA-DPB1 alleles express a GGPM epitope in the same region [3]. Therefore, the pathogenic antibody is likely to bind to this epitope of the HLA-DP molecule. Although tests for anti-MICA, anti-MICB and anti-angiotensin II type 1 receptor antibodies were negative, we cannot formally exclude that other non-HLA antibodies might play a role in this case, but this possibility is rather unlikely.
P.E. Cippà et al. / Human Immunology 75 (2014) 462–465
This case of AMR is unique because of the particular HLA-mismatch and because of the unexpected absence of anti-MHC class I reactivity despite three mismatches in the HLA-A and HLA-B locus, but it has a particular immunological relevance, since it demonstrates for the first time that a single HLA-DP mismatch might be sufficient to induce de novo donor-specific antibodies leading to acute and chronic AMR. The other HLA class II molecules DR and DQ seem to be more immunogenic than HLA-DP and might therefore mask the role of HLA-DP mismatches in larger studies [9]. However, the case presented here demonstrates the clinical relevance of HLA-DP. HLA-DP typing and matching should be considered for living donation and in particular for patients with preformed anti-DP antibodies to improve outcome after renal transplantation. References [1] Colvin RB, Smith RN. Antibody-mediated organ-allograft rejection. Nat Rev Immunol 2005;5:807. [2] Fehr T, Gaspert A. Antibody-mediated kidney allograft rejection: therapeutic options and their experimental rationale. Transpl Int 2012;25:623. [3] Billen EV, Christiaans MH, Doxiadis II, Voorter CE, van den Berg-Loonen EM. HLA-DP antibodies before and after renal transplantation. Tissue Antigens 2010;75:278. [4] Thaunat O, Hanf W, Dubois V, McGregor B, Perrat G, Chauvet C, et al. Chronic humoral rejection mediated by anti-HLA-DP alloantibodies: insights into the
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
465
role of epitope sharing in donor-specific and non-donor specific alloantibodies generation. Transpl Immunol 2009;20:209. Goral S, Prak EL, Kearns J, Bloom RD, Pierce E, Doyle A, et al. Preformed donordirected anti-HLA-DP antibodies may be an impediment to successful kidney transplantation. Nephrol Dial Transplant 2008;23:390. Jolly EC, Key T, Rasheed H, Morgan H, Butler A, Pritchard N, et al. Preformed donor HLA-DP-specific antibodies mediate acute and chronic antibodymediated rejection following renal transplantation. Am J Transplant 2012;12:2845. Qiu J, Cai J, Terasaki PI, El-Awar N, Lee JH. Detection of antibodies to HLA-DP in renal transplant recipients using single antigen beads. Transplant 2005;80:1511. Samaniego M, Mezrich J, Torrealba J, Lorentzen D, Schadde E, Djamali A, et al. C4d-positive acute antibody-mediated rejection due to anti-HLA-DP antibody: a tale of one patient and a review of the University of Wisconsin experience. Clin Transpl 2006:503. Mytilineos J, Deufel A, Opelz G. Clinical relevance of HLA-DPB locus matching for cadaver kidney retransplants: a report of the collaborative transplant study. Transplant 1997;63:1351. Couzi L, Araujo C, Guidicelli G, Bachelet T, Moreau K, Morel D, et al. Interpretation of positive flow cytometric crossmatch in the era of the single-antigen bead assay. Transplant 2011;91:527. Riethmuller S, Ferrari-Lacraz S, Muller MK, Raptis DA, Hadaya K, Rusi B, et al. Donor-specific antibody levels and three generations of crossmatches to predict antibody-mediated rejection in kidney transplantation. Transplant 2010;90:160. Varga Z, Gaspert A, Behnke S, von Teichman A, Fritzsche F, Fehr T. Tubular and endothelial chimerism in renal allografts using fluorescence and chromogenic in situ hybridization (FISH, CISH) technology. Pathol Int 2012;62:254.
