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P052 Antibody mediated rejection in a cardiac transplant case; to C or not to C
98
P052
Abstracts / Human Immunology 79 (2018) 58–187
ANTIBODY MEDIATED REJECTION IN A CARDIAC TRANSPLANT CASE; TO C OR NOT TO C Ellie Saunders 1, Serena Franklin 1, Brent Clifton 1, Kristy Crissler 1, Scott Mcdonlad 1, Cathi Murphy 2, Taba Kheradmand 3. 1 Midwest Transplant Network, Westwood, KS, United States; 2 Southwest Immunodiagnostics, San Antonio, TX, United States; 3 Midwest Transplant Network, Kansas City, MO, United States. Background: Due to the less sensitive nature of the historical assays and lack of data, and the low expression level of the HLA-C antigens, the role of pre-transplant HLA-C antigens in solid organ transplantation is less clear. Herein we describe a cardiac transplant case were patient was transplanted in the presence of donor specific antibody (DSA) to HLA-C antigen and a negative flow cytometric crossmatch; however, shortly post-transplant they developed antibody mediated rejection (AMR) due to C1q-fixing DSA to the HLA-C antigen. Method: IgG and C1q-fixing HLA antibodies were detected using the Single Antigen luminex solid phase assay (One Lambda, Thermo Fisher). While the sole sensitizing antigen could not be determined, HLAMatchmaker was utilized to identify antibody specificities to a shared epitope, 76VRN. Flow cytometric crossmatches (FCXM) were performed on negatively selected (StemCell TechnologiesTM pronase-treated lymphocytes. T cell FlowDSA crossmatch (One Lambda, Thermo Fisher) was performed at the Southwest Immunodiagnostics, Inc., Laboratory. Results: Regardless of the presence of relatively strong DSA to HLA-C antigens, MFI ranging from 6,000– 14,000, T and B cell FCXM were negative. To further understand the clinical relevance of antibodies to the HLA-C antigens, sera was sent out for FlowDSA crossmatch testing. Two surrogate donors, one with DSA to C7 and one with DSA to C7 and C8, were both T cell positive by FlowDSA crossmatch. Nevertheless, due to clinical urgency patient was transplanted in the presence of pre-transplant DSA to HLA-C7 (MFI 12,600) and a negative FCXM. Approximately 10 days post-transplant patient developed clinical and biopsy proven AMR. Single antigen solid phase assay showed elevated DSA to C7 (MFI 19,500) and C17 (MFI 6,500). In agreement with the biopsy results, the post-transplant C1q Single Antigen assay was positive for C7 as well as the antigens carrying the shared epitope 76VRN. Conclusion: Pre-formed HLA-C antibodies to shared epitopes can cause acute AMR. The FlowDSA crossmatch enhanced detection of such deleterious antibodies more efficiently than the conventional flow crossmatch assay. Six months post-transplant the patient is stable; however, the long term clinical relevance of such antibodies on the graft outcome remains to be determined.
P053
DP DONOR SPECIFIC ANTIBODIES PRE-RENAL TRANSPLANT: MEAN FLUORESCENCE INTENSITY AND EPITOPE PATTERN ALONE IS NOT PREDICTIVE OF CROSSMATCH RESULT OR CLINICAL OUTCOME Teri-Lynn O. Steeves 1, Bruce Young 2, Kylie Lepic 3, Christine Ribic 4. 1 McMaster Medical Centre Hamilton 2 Health Sciences, Hamilton, ON, Canada; St Joseph’s Healthcare, Hamilton, ON, Canada; 3 McMaster University, Hamilton, ON, Canada; 4 McMaster University, St. Joseph’s Healthcare Hamilton, Hamilton ON, Canada. The clinical significance of HLA-DP donor specific antibodies (DSA) detected with solid phase assays in recipients of renal transplants remains poorly defined. Recent literature has elucidated that many patients have a HLA-DP antibody pattern of reactivity against broad cross-reactive epitopes which may be more clinically significant. Typically, a DSA that reacts at a mean fluorescence intensity (MFI) of greater than 5000 results in positive crossmatch. We present two cases with pre-transplant HLA-DP DSAs at high MFI (>5000) directed against cross-reactive epitopes identified on virtual crossmatch which resulted in negative and positive flow crossmatch respectively. Case 1 is 57 yr old male who received a deceased donor renal transplant in 2015. He was known to have a HLA-DP9 DSA DED epitope reactivity pattern at 7,333 MFI detected by Luminex bead assay against his donor on peak serum. Pre-transplant crossmatch was negative and he proceeded to transplant. Current creatinine is stable at 150 lmol/L and there are no episodes of rejection. Case 2 is 67 yr old female who remains on the deceased donor list awaiting renal transplant with a cPRA of 99%. She has had 3 offers where she has had a HLA-DP1 or HLA-DP3 DSA DEAV epitope reactivity pattern at 10,000 MFI against her donors resulting in flow B-cell positive crossmatch. Crossmatch with donor cells known not to express DP DEAV epitope antigens have been negative. The current cases illustrate that HLADP DSAs at high MFI with epitope reactivity may not necessarily result in a positive flow crossmatch. The differential crossmatch results for these two recipients may be related to variable HLA-DPB1 antigen expression in the donor rather than MFI and/or epitope pattern reaction in the recipient. Avoidance of transplant in the context of high MFI HLA-DP DSA epitope cross-reactivity pattern may not be necessary and can be associated with acceptable clinical outcome in the context of a negative pre-transplant crossmatch. HLA-DPA DSAs that have an epitope pattern of reactivity resulting in positive crossmatch are still avoided. Adding DP DSAs to the allocation algorithm without the opportunity to perform flow crossmatch does not allow for accurate immunological risk assessment and may prevent the opportunity for successful transplant. C. Ribic: 1. Grant/Research Support; Company/Organization; Leo Pharma; Astellas. 3. Speaker’s Bureau; Company/Organization; Leo Pharma; Astellas.
P052
Abstracts / Human Immunology 79 (2018) 58–187
ANTIBODY MEDIATED REJECTION IN A CARDIAC TRANSPLANT CASE; TO C OR NOT TO C Ellie Saunders 1, Serena Franklin 1, Brent Clifton 1, Kristy Crissler 1, Scott Mcdonlad 1, Cathi Murphy 2, Taba Kheradmand 3. 1 Midwest Transplant Network, Westwood, KS, United States; 2 Southwest Immunodiagnostics, San Antonio, TX, United States; 3 Midwest Transplant Network, Kansas City, MO, United States. Background: Due to the less sensitive nature of the historical assays and lack of data, and the low expression level of the HLA-C antigens, the role of pre-transplant HLA-C antigens in solid organ transplantation is less clear. Herein we describe a cardiac transplant case were patient was transplanted in the presence of donor specific antibody (DSA) to HLA-C antigen and a negative flow cytometric crossmatch; however, shortly post-transplant they developed antibody mediated rejection (AMR) due to C1q-fixing DSA to the HLA-C antigen. Method: IgG and C1q-fixing HLA antibodies were detected using the Single Antigen luminex solid phase assay (One Lambda, Thermo Fisher). While the sole sensitizing antigen could not be determined, HLAMatchmaker was utilized to identify antibody specificities to a shared epitope, 76VRN. Flow cytometric crossmatches (FCXM) were performed on negatively selected (StemCell TechnologiesTM pronase-treated lymphocytes. T cell FlowDSA crossmatch (One Lambda, Thermo Fisher) was performed at the Southwest Immunodiagnostics, Inc., Laboratory. Results: Regardless of the presence of relatively strong DSA to HLA-C antigens, MFI ranging from 6,000– 14,000, T and B cell FCXM were negative. To further understand the clinical relevance of antibodies to the HLA-C antigens, sera was sent out for FlowDSA crossmatch testing. Two surrogate donors, one with DSA to C7 and one with DSA to C7 and C8, were both T cell positive by FlowDSA crossmatch. Nevertheless, due to clinical urgency patient was transplanted in the presence of pre-transplant DSA to HLA-C7 (MFI 12,600) and a negative FCXM. Approximately 10 days post-transplant patient developed clinical and biopsy proven AMR. Single antigen solid phase assay showed elevated DSA to C7 (MFI 19,500) and C17 (MFI 6,500). In agreement with the biopsy results, the post-transplant C1q Single Antigen assay was positive for C7 as well as the antigens carrying the shared epitope 76VRN. Conclusion: Pre-formed HLA-C antibodies to shared epitopes can cause acute AMR. The FlowDSA crossmatch enhanced detection of such deleterious antibodies more efficiently than the conventional flow crossmatch assay. Six months post-transplant the patient is stable; however, the long term clinical relevance of such antibodies on the graft outcome remains to be determined.
P053
DP DONOR SPECIFIC ANTIBODIES PRE-RENAL TRANSPLANT: MEAN FLUORESCENCE INTENSITY AND EPITOPE PATTERN ALONE IS NOT PREDICTIVE OF CROSSMATCH RESULT OR CLINICAL OUTCOME Teri-Lynn O. Steeves 1, Bruce Young 2, Kylie Lepic 3, Christine Ribic 4. 1 McMaster Medical Centre Hamilton 2 Health Sciences, Hamilton, ON, Canada; St Joseph’s Healthcare, Hamilton, ON, Canada; 3 McMaster University, Hamilton, ON, Canada; 4 McMaster University, St. Joseph’s Healthcare Hamilton, Hamilton ON, Canada. The clinical significance of HLA-DP donor specific antibodies (DSA) detected with solid phase assays in recipients of renal transplants remains poorly defined. Recent literature has elucidated that many patients have a HLA-DP antibody pattern of reactivity against broad cross-reactive epitopes which may be more clinically significant. Typically, a DSA that reacts at a mean fluorescence intensity (MFI) of greater than 5000 results in positive crossmatch. We present two cases with pre-transplant HLA-DP DSAs at high MFI (>5000) directed against cross-reactive epitopes identified on virtual crossmatch which resulted in negative and positive flow crossmatch respectively. Case 1 is 57 yr old male who received a deceased donor renal transplant in 2015. He was known to have a HLA-DP9 DSA DED epitope reactivity pattern at 7,333 MFI detected by Luminex bead assay against his donor on peak serum. Pre-transplant crossmatch was negative and he proceeded to transplant. Current creatinine is stable at 150 lmol/L and there are no episodes of rejection. Case 2 is 67 yr old female who remains on the deceased donor list awaiting renal transplant with a cPRA of 99%. She has had 3 offers where she has had a HLA-DP1 or HLA-DP3 DSA DEAV epitope reactivity pattern at 10,000 MFI against her donors resulting in flow B-cell positive crossmatch. Crossmatch with donor cells known not to express DP DEAV epitope antigens have been negative. The current cases illustrate that HLADP DSAs at high MFI with epitope reactivity may not necessarily result in a positive flow crossmatch. The differential crossmatch results for these two recipients may be related to variable HLA-DPB1 antigen expression in the donor rather than MFI and/or epitope pattern reaction in the recipient. Avoidance of transplant in the context of high MFI HLA-DP DSA epitope cross-reactivity pattern may not be necessary and can be associated with acceptable clinical outcome in the context of a negative pre-transplant crossmatch. HLA-DPA DSAs that have an epitope pattern of reactivity resulting in positive crossmatch are still avoided. Adding DP DSAs to the allocation algorithm without the opportunity to perform flow crossmatch does not allow for accurate immunological risk assessment and may prevent the opportunity for successful transplant. C. Ribic: 1. Grant/Research Support; Company/Organization; Leo Pharma; Astellas. 3. Speaker’s Bureau; Company/Organization; Leo Pharma; Astellas.