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Abstracts / Human Immunology 74 (2013) 1–49
VIRTUAL CROSSMATCH VERSUS FINAL FLOW CYTOMETRIC CROSSMATCH – REVIEW OF 2000 CROSSMATCHES PERFORMED IN THE PAST THREE YEARS. Yu Sun, Yonghong Song, Liang Wan, Wendy E. Wegner, Dong-Feng Chen. Clinical Transplantation Immunology Laboratory, Duke University Medical Center, Durham, NC, USA. Aim: Solid phase immunoassays enable us to identify unacceptable donor HLA specific antigens (DSA) which allows for the prediction of compatible donor/recipient combinations. This process is referred to as the virtual crossmatch (vXM). The aim of the study was to evaluate the performance of the vXM against the final flow cytometric crossmatch (FCXM). Methods: All FCXM performed in the past three years were included in this study. Flow cytometry antibody screening and Luminex single antigen bead assay (LSA) were performed to determine the presence of HLA antibodies and their specificities. MFI = 1000 was used as cutoff for LSA. A final FCXM either prospective or retrospective for the transplant recipients was performed with potential donors selected upon the vXM. Donor cells used for final crossmatch were treated with pronase. Results: Total 2070 FCMX were recorded and analyzed in the study. Among these crossmatches, 1891 were vXM negative, 768 crossmatches were performed for HLA sensitized recipients with 179 positive vXM due to presence of DSA. There were total 297 positive final FCXM, of them 123 were expected and 174 (9%) were unexpected compared with the vXM results. The overall prediction rate of the final negative FCXM was 91%. The overall unexpected positive final FCXM was 8%. The majority of the unexpected final T cell positive and B cell negative FCXM became negative when the FCXM repeated with non-pronase treated donor cells. Conclusions: Our vXM practice provided a >90% correct predication of negative FCXM. We could expected that the unexpected positive final FCXM mainly caused by non-HLA reactivity, for example, the pronase treatment and/or presence of antibodies not directed to HLA because the current LSA could finely define the specificities of HLA antibodies. However, it could not be excluded that the presence of anti-DP and/or DQA1 antibodies could trigger a positive B cell FCXM in cases where donors’ DP and DQA1 were not typed. This will be further investigated.
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ANALYSIS OF ANTI-HLA ANTIBODIES IN SENSITIZED KIDNEY TRANSPLANT CANDIDATES SUBJECTED TO DESENSITIZATION WITH INTRAVENOUS IMMUNOGLOBULIN AND RITUXIMAB. Andrew L. Lobashevsky 1,2, Nancy G. Higgins 2, Kevin M. Rosner 2, Muhammad A. Mujtaba 1, William C. Goggins 3, Tim E. Taber 1. 1 Department of Medicine, Indiana University, Indianapolis, IN, USA; 2 Indiana University Health Transplant Center, Transplant Immunology Laboratory, Indianapolis, IN, USA; 3 Department of Surgery, Indiana University, Indianapolis, IN, USA. Aim: The aim of this study was to investigate the effect of desensitization (DS) with intravenous immunoglobulin and rituximab (IVIG-RIT-IVIG) on the antibody profile in highly sensitized kidney transplant candidates (TC). Methods: In 31 kidney transplant candidates (calculated percent reactive antibodies [cPRA], 34% to 99%), DS included intravenous immunoglobulin on days 0 and 30 and a single dose of rituximab on day 15. AntiHLA antibodies were analyzed before and after immunomodulation using the Luminex single antigen solid phase analysis. Results: Reduction of cPRA from 25% to 50% was noted for anti-class I (5 patients, within 20 to 60 d) and anti-class II (3 patients, within 10 to 20 d) antibodies. After initial reduction of cPRA, it increased within 120 days. In 24 patients, decrease in mean fluorescence intensity (MFI) of antibodies by more than 50% was noted at follow-up, but there was no reduction of cPRA. Rebound occurred in 65% patients for anti-class I antibodies at 350 days and anti-class II antibodies at 101 to 200 days. Probability of rebound effect was higher in patients with MFI > 10700 before DS, anti-class II antibodies, and history of previous transplant. Conclusions: The desensitization protocol consisting of IVIG-RIT-IVIG had selective efficacy in highly sensitized kidney TC because of the short period with antibody reduction and high frequency of rebound effect.
15-OR
Abstracts / Human Immunology 74 (2013) 1–49
VIRTUAL CROSSMATCH VERSUS FINAL FLOW CYTOMETRIC CROSSMATCH – REVIEW OF 2000 CROSSMATCHES PERFORMED IN THE PAST THREE YEARS. Yu Sun, Yonghong Song, Liang Wan, Wendy E. Wegner, Dong-Feng Chen. Clinical Transplantation Immunology Laboratory, Duke University Medical Center, Durham, NC, USA. Aim: Solid phase immunoassays enable us to identify unacceptable donor HLA specific antigens (DSA) which allows for the prediction of compatible donor/recipient combinations. This process is referred to as the virtual crossmatch (vXM). The aim of the study was to evaluate the performance of the vXM against the final flow cytometric crossmatch (FCXM). Methods: All FCXM performed in the past three years were included in this study. Flow cytometry antibody screening and Luminex single antigen bead assay (LSA) were performed to determine the presence of HLA antibodies and their specificities. MFI = 1000 was used as cutoff for LSA. A final FCXM either prospective or retrospective for the transplant recipients was performed with potential donors selected upon the vXM. Donor cells used for final crossmatch were treated with pronase. Results: Total 2070 FCMX were recorded and analyzed in the study. Among these crossmatches, 1891 were vXM negative, 768 crossmatches were performed for HLA sensitized recipients with 179 positive vXM due to presence of DSA. There were total 297 positive final FCXM, of them 123 were expected and 174 (9%) were unexpected compared with the vXM results. The overall prediction rate of the final negative FCXM was 91%. The overall unexpected positive final FCXM was 8%. The majority of the unexpected final T cell positive and B cell negative FCXM became negative when the FCXM repeated with non-pronase treated donor cells. Conclusions: Our vXM practice provided a >90% correct predication of negative FCXM. We could expected that the unexpected positive final FCXM mainly caused by non-HLA reactivity, for example, the pronase treatment and/or presence of antibodies not directed to HLA because the current LSA could finely define the specificities of HLA antibodies. However, it could not be excluded that the presence of anti-DP and/or DQA1 antibodies could trigger a positive B cell FCXM in cases where donors’ DP and DQA1 were not typed. This will be further investigated.
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ANALYSIS OF ANTI-HLA ANTIBODIES IN SENSITIZED KIDNEY TRANSPLANT CANDIDATES SUBJECTED TO DESENSITIZATION WITH INTRAVENOUS IMMUNOGLOBULIN AND RITUXIMAB. Andrew L. Lobashevsky 1,2, Nancy G. Higgins 2, Kevin M. Rosner 2, Muhammad A. Mujtaba 1, William C. Goggins 3, Tim E. Taber 1. 1 Department of Medicine, Indiana University, Indianapolis, IN, USA; 2 Indiana University Health Transplant Center, Transplant Immunology Laboratory, Indianapolis, IN, USA; 3 Department of Surgery, Indiana University, Indianapolis, IN, USA. Aim: The aim of this study was to investigate the effect of desensitization (DS) with intravenous immunoglobulin and rituximab (IVIG-RIT-IVIG) on the antibody profile in highly sensitized kidney transplant candidates (TC). Methods: In 31 kidney transplant candidates (calculated percent reactive antibodies [cPRA], 34% to 99%), DS included intravenous immunoglobulin on days 0 and 30 and a single dose of rituximab on day 15. AntiHLA antibodies were analyzed before and after immunomodulation using the Luminex single antigen solid phase analysis. Results: Reduction of cPRA from 25% to 50% was noted for anti-class I (5 patients, within 20 to 60 d) and anti-class II (3 patients, within 10 to 20 d) antibodies. After initial reduction of cPRA, it increased within 120 days. In 24 patients, decrease in mean fluorescence intensity (MFI) of antibodies by more than 50% was noted at follow-up, but there was no reduction of cPRA. Rebound occurred in 65% patients for anti-class I antibodies at 350 days and anti-class II antibodies at 101 to 200 days. Probability of rebound effect was higher in patients with MFI > 10700 before DS, anti-class II antibodies, and history of previous transplant. Conclusions: The desensitization protocol consisting of IVIG-RIT-IVIG had selective efficacy in highly sensitized kidney TC because of the short period with antibody reduction and high frequency of rebound effect.