Differences in Reactivity of HLA-Specific Antibodies May Be Explained By Differences in Their Affinities for Selected Epitopes on HLA Proteins

S. Daga,^1,2 D. Lowe,⁶ R. Buchli,⁵ J. Collard,⁵ A. Mulder,⁸ C. McMurtrey,^4,5 H. Moyse,⁷ N. Evans,⁷ N. Krishnan,² W. Hildebrand,^4,5 F. Claas,⁸ D. Briggs,³ D. Zehnder,^1,2 D. Mitchell,¹ R. Higgins.^1,2

¹Clinical Sciences Research Laboratories, University of Warwick, Coventry, United Kingdom
²Renal Unit, University Hospital, Coventry and Warwickshire NHS Trust, Coventry, United Kingdom
³Department of Histocompatibility and Immunogenetics, NHS Blood and Transplant, Birmingham, United Kingdom
⁴University of Oklahoma Health Science Center, Oklahoma City
⁵Pure Protein LLC, Oklahoma City
⁶Department of Histocompatibility and Immunogenetics, Royal Liverpool University Hospital, Liverpool, United Kingdom
⁷School of Engineering, University of Warwick, Coventry, United Kingdom
⁸Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, Netherlands.

Meeting: 2015 American Transplant Congress

Abstract number: B246

Keywords: Epitopes, Highly-sensitized, HLA antibodies, Kidney transplantation

Session Information

Session Name: Poster Session B: Translational Genetics and Proteomics in Transplantation

Session Type: Poster Session

Date: Sunday, May 3, 2015

Session Time: 5:30pm-6:30pm

Presentation Time: 5:30pm-6:30pm

Location: Exhibit Hall E

Affinity of IgG immunoglobulins for antigen varies and matures within the evolution of immune responses. Affinity is likely to be different for different epitope-antibody interactions and for the same epitope on different HLA antigens.

The mouse monoclonal antibody W6/32 and five human monoclonal HLA-specific antibodies were studied. Binding kinetics were compared between sensitizing antigen and other cross-reactive antigens sharing epitopes for human monoclonal antibodies. We compared relative MFI values derived from Luminex assay and calculated affinities for the same concentration of the panel of monoclonal HLA-specific antibodies.

Calculated antibody affinities were different for different HLA antigens despite the presence of the same epitopes. Dissociation constants (KD) values were between 10-8 to 10-10 M for the human monoclonal HLA-specific antibodies. In every case, higher affinity and slower dissociation rates were observed with the original sensitizing antigen compared to the same epitope(s) on other HLA antigens. The difference between the calculated dissociation constants ranged from two- to ten-fold. Luminex MFI values for the same concentration of each monoclonal antibody on different HLA specificities differed, the rank order being similar to the affinities.

Thus, kinetic analysis of antibody binding to HLA antigens in real time using multi-channel surface plasmon resonance has been carried out successfully and allows for the study of additional parameters such as association and dissociation rates that are not measurable in current solid phase platforms such as Luminex.

To cite this abstract in AMA style:

Daga S, Lowe D, Buchli R, Collard J, Mulder A, McMurtrey C, Moyse H, Evans N, Krishnan N, Hildebrand W, Claas F, Briggs D, Zehnder D, Mitchell D, Higgins R. Differences in Reactivity of HLA-Specific Antibodies May Be Explained By Differences in Their Affinities for Selected Epitopes on HLA Proteins [abstract]. Am J Transplant. 2015; 15 (suppl 3). https://atcmeetingabstracts.com/abstract/differences-in-reactivity-of-hla-specific-antibodies-may-be-explained-by-differences-in-their-affinities-for-selected-epitopes-on-hla-proteins/. Accessed May 19, 2025.

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