Correlation of Complement Activating Donor Specific Antibodies as Measured by C3d and Cross-Match Status.
1Warwick Medical School, University of Warwick, Coventry, United Kingdom
2Nephrology and Transplantation, University Hospitals Coventrya and Warwickshire, Coventry, United Kingdom
3Histocompatibility and Immunogenetics, NHS Blood and Transfusion, Birmingham, United Kingdom
4Nephrology and Transplantation, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
Meeting: 2017 American Transplant Congress
Abstract number: C14
Keywords: Alloantibodies, Graft survival, Histocompatibility antigens, HLA antibodies
Session Information
Session Name: Poster Session C: Antibody and B Cell
Session Type: Poster Session
Date: Monday, May 1, 2017
Session Time: 6:00pm-7:00pm
Presentation Time: 6:00pm-7:00pm
Location: Hall D1
Introduction. Complement dependent cytotoxicity, first described in 1969 is the only functional assay studying complement activation. C3d assay is developed recently to study complement activation using solid phase assay. No studies that have correlated the CDC and Flow Crossmatch (FC) status to C3d assay, especially in patients who have undergone Human Leucocyte Antigen -Antibody Incompatible Transplant (HLA-AIT).
Methods: We analysed samples from 121 HLA-AIT who had pre-transplant IgG Donor specific antibodies(DSA) and were either crossmatch positive or negative.C3d (Immucor) assay was performed at preconditioning/pre-transplant and the results correlated with CDC and FC crossmatch.Results: Of 121 patients, 25 were CDC positive and 61 were FC positive. 35 patients were crossmatch negative but positive for single antigen bead. There was no linear correlation between: C3d MFI values and IgG MFI (R2 0.39); C3d MFI and CDC titres (R2 0.30); C3d MFI and Flow highest RMF (R2 0.07). We compared C3d positivity with the XM status. There is significant association between C3d positivity and overall XM (p <0.0001); CDC positivity (p <0.0001); FC (excluding CDC cases) p =0.025.
C3d presence has very high specificity to predict crossmatch as detailed in table 1.
| Overall | CDC crossmatch | FC | |
| Sensitivity | 41.17% | 80% | 24.6% |
| Specificity | 97.14% | 82.29% | 94.2% |
| Positive Predictitive value | 97.24 | 54% | 88.21 |
| Negative Predictive value | 48% | 94% | 41.82% |
Discussion: C3d positivity is strongly associated with crossmatch positivity and is associated with poor allograft survival. C3d MFI values and cross-match titres does not correlate in a linear fashion; this not surprising as the measurement uses different techniques.High specificity may make this test very useful in virtual cross-match, as allograft survival in C3d negative cohort is equivalent to standard living donor transplantation. C3d can be additional biomarker in centres that do not perform CDC assay and post transplant monitoring where donor cells are not available.
CITATION INFORMATION: Babu A, Krishnan N, Briggs D, Mitchell D, Daga S. Correlation of Complement Activating Donor Specific Antibodies as Measured by C3d and Cross-Match Status. Am J Transplant. 2017;17 (suppl 3).
To cite this abstract in AMA style:
Babu A, Krishnan N, Briggs D, Mitchell D, Daga S. Correlation of Complement Activating Donor Specific Antibodies as Measured by C3d and Cross-Match Status. [abstract]. Am J Transplant. 2017; 17 (suppl 3). https://atcmeetingabstracts.com/abstract/correlation-of-complement-activating-donor-specific-antibodies-as-measured-by-c3d-and-cross-match-status/. Accessed May 11, 2025.« Back to 2017 American Transplant Congress