P097 High prevalence of anti-angiotensin II type 1 receptor antibody in HLA-sensitized transplant candidates

Aims Renal transplant (RTX) candidates with pre-formed anti-HLA antibody (HLA-Ab) have lower transplantation rates and increased mortality. Anti-angiotensin II type 1 receptor antibody (AT1R-Ab) has recently been associated with allograft loss and antibody-mediated rejection. The aim of the present study was to evaluate: (1) the prevalence of anti-angiotensin receptor 1 antibody (AT1R-Ab) in RTX candidates with circulating HLA-Ab and (2) AT1R-Ab response to VDS. Methods Thirty-nine patients receiving desensitization therapy had HLA-Ab levels determined by single-antigen bead array (Luminex). Mean fluorescence intensity (MFI) of the strongest HLA-Ab (immunodominant antibody -iDSA) was measured before and after therapy. A successful response was considered when iDSA decreased >50% at nadir versus pre-desensitization. Serum samples were also tested by ELISA for the presence of AT1R-Ab (U/mL after 1:50 dilution), before and after desensitization. Results A high proportion of candidates with HLA-Ab exhibited AT1R-Ab (20/39, 51%). A good response of AT1R-Ab to therapy was observed in 18/20 patients [Figure 1]: 17.4 ± 12.3 pre versus 10.9 ± 13.1 U/mL post therapy, p = 0.0009). iDSA reduction with desensitization was observed in 13/20 patients – 7996 ± 2580 pre versus 4410 ± 2695 MFI post therapy, p = 0.0001). 12/20 patients had both iDSA and AT1R-Ab reduction by therapy, 6/20 responded to AT1R-Ab only, 1/20 responded to iDSA only, and 1/20 was a non-responder. AT1R-Ab levels were more elevated in Caucasians then in African-Americans both before (20.7 ± 14.9 versus 12.3 ± 3.7 U/mL, p = 0.1), and after desensitization (14.7 ± 15.9 versus 5.2 ± 2.9 U/mL, p = 0.1). Conclusions More than half of HLA-sensitized candidates exhibit AT1R-Ab. This initial desensitization experience consistently provided substantial reductions both in HLA-Ab and AT1R-Ab levels in an unselected, highly sensitized kidney transplant candidate population. Download : Download high-res image (380KB) Download : Download full-size image