P161 Kidney allograft outcomes associated with locus specific IgG antibodies to donor class I

Abstract

Aim Early and late post transplant complications have been associated with antibodies (Abs) directed against donor HLA; however, the impact of pre-transplant Abs directed against donor HLA-C remains unresolved. In view of diminished display of HLA-C antigens on the cell surface compared to HLA-A or-B antigens, we hypothesized that the impact of pre-transplant Abs to donor HLA-C will be lesser compared to Abs directed at donor HLA-A and B. In the current investigation we studied the impact of circulating pre-transplant IgG antibodies to donor HLA-C locus antigens alone as compared to Abs to HLA- or B locus antigens. Methods We conducted a retrospective review of records of 1252 kidney allograft recipients transplanted at our center between January 2010 and January 2016 to identify patients with circulating pre-transplant IgG Abs directed at kidney donor HLA-A, B or C locus antigens. Abs were detected and reported using the Luminex Single Antigen Bead assay for HLA Class I. Pre and post-transplant data were collected and graft outcomes of 16 kidney graft recipients with Abs to HLA-C locus antigens alone were compared to the outcomes of 56 recipients with Abs to HLA-A or B locus antigens. Results The mean pre-transplant MFI value of DSA in those with Abs to HLA- A or B antigens was 3880 ± 3023 and 4331 ± 5540 in those with Abs to HLA- C antigens (P = 0.4). The one-year acute rejection rate was 6% in those with DSA to HLA-C antigens and 20% in those with DSA to HLA-A or B antigens (Fig. 1A). Incidence of AMR was increased in those with DSA-MFI value greater than 6000 (Fig. 1B). Kidney allograft survival rate was 100% in those with DSA to HLA-C antigens and 95% in those with DSA to HLA-A or B locus antigens (P > 0.05). Conclusions Our observations support the concept that circulating pre-transplant IgG antibodies directed at kidney donor HLA-C locus alone do not negatively impact kidney allograft outcomes and suggests that listing unacceptable HLA C locus antigens based on MFI of Single Antigen Bead Assay requires additional scrutiny and due caution. Download high-res image (125KB) Download full-size image