HLA Specific Antibody Levels after EDTA Treatment in CDC Crossmatch Positive and Negative Sera with Known Donor-Specific Antibodies

J. Lauronen¹, T. Jaatinen¹, J. Holgersson², C. Naper³, J. Peräsaari¹

¹Histocompatibility Laboratory, Finnish Red Cross Blood Service, Helsinki, Finland, ²Department of Laboratory Medicine, Sahlgrenska Academy at University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden, ³Histocompatibility Laboratory, Oslo University Hospital, Oslo, Norway

Meeting: 2020 American Transplant Congress

Abstract number: A-284

Keywords: Antibodies, Histocompatibility, Histocompatibility antigens, HLA antibodies

Session Information

Session Name: Poster Session A: Histocompatibility and Immunogenetics

Session Type: Poster Session

Date: Saturday, May 30, 2020

Session Time: 3:15pm-4:00pm

Presentation Time: 3:30pm-4:00pm

Location: Virtual

*Purpose: Ethylenediaminetetraacetic acid (EDTA) treatment of serum samples overcomes the prozone effect that may interfere with solid phase HLA specific antibody analyses. In patients with platelet refractoriness we have seen that EDTA leads to increased mean fluorescence intensity (MFI) of most detected antibodies. We analyzed the effect of EDTA treatment on selected serum samples with known donor-specific antibodies (DSA) that tested either negative or positive in complement dependent cytotoxic crossmatch (CDC) tests. We hypothesized that the antibodies were stronger in CDC positive as compared to negative sera, and that the true MFI levels of these antibodies were disguised by the prozone effect.

*Methods: 60 DSA positive (30 CDC positive, 30 CDC negative) serum samples from sensitized patients on the kidney transplant waiting lists were analyzed. Samples were collected from Finnish Red Cross Blood Service, Sahlgrenska University Hospital and Oslo University Hospital. Analyses of HLA antibodies were performed in Helsinki with and without EDTA using LABScreen™ Single Antigen kits (One Lambda, Thermo Fisher) in the Luminex and with the Fusion 4.2 software. A mean MFI increase of more than 1000 was considered significant.

*Results: The MFI levels of native sera were higher in CDC positive [sum (range) of each bead MFI means; 76933 (6850-253042)] as compared to CDC negative cases [31169 (4865-132994)]. There was no statistically significant difference between the MFI levels of EDTA-treated and native sera in any of the detected antibody specifities [sum (range) of MFI means of EDTA treated samples were 30878 (4582-136908) and 78465 (5726-260221) in CDC negative and positive, respectively]. None of the detected antibody MFI means increased >1000 MFI; change was between -174 to 255 in CDC negative and -132 to 369 in CDC positive sera. Interestingly, the mean MFI levels increased slightly with EDTA treatment in 76/97 HLA class I antibodies of CDC positive cases as compared to only 19/97 of the CDC negative cases (p>0,001).

*Conclusions: The MFI levels of HLA specific antibodies were higher in CDC positive as compared to CDC negative patients. The MFI levels did not change drastically after EDTA treatment, although a slight increase was observed for many HLA class I specific antibodies in CDC positive cases.

To cite this abstract in AMA style:

Lauronen J, Jaatinen T, Holgersson J, Naper C, Peräsaari J. HLA Specific Antibody Levels after EDTA Treatment in CDC Crossmatch Positive and Negative Sera with Known Donor-Specific Antibodies [abstract]. Am J Transplant. 2020; 20 (suppl 3). https://atcmeetingabstracts.com/abstract/hla-specific-antibody-levels-after-edta-treatment-in-cdc-crossmatch-positive-and-negative-sera-with-known-donor-specific-antibodies/. Accessed July 9, 2025.

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