75-P

Abstract

Aim To determine the frequency of donor specific HLA antibody (DSA) to DQ alpha in renal post-transplant recipients. Donor DQA1 typing is not a routine procedure under UNOS. Frequency of post-transplant DQ alpha DSA and possible importance in post-transplant monitoring is not well-studied. Methods Retrospective review of post-transplant HLA antibody test results. Reviewed are all HLA antibody test results between January 2010 and April 2012 for the patients who received a deceased or living donor kidney at our center. HLA typing of donors and recipients was tested by serology or SSO/SSP. HLA antibody was tested by solid phase methods (LABScreen PRA and LABScreen Single Antigen beads, One Lambda). Current antibody monitoring schedule for low risk patients (no pre-formed or de novo DSA and stable creatinine) is 9 times in the first year, every 6 months until the 3rd year, then annually. Additional tests are performed if higher risk or suspected rejections. If DQ alpha antibody is detected, donor DQA1 was typed retrospectively using frozen cells. Results Post-transplant HLA antibody was tested on 158 recipients: 27 pediatrics and 131 adults (average 46.3 years old). Results represent data points from two months to 26 years post-transplant (average 5.0 years). In all patients, pre-transplant crossmatch was either compatible by CDC method, or compatible/weakly incompatible by flow cytometry method. Of the 158 patients, DSA (either de novo or preformed) was detected in 29 patients (18.4%). Detected were class I DSA only in 3 patients, class II DSA only in 20 patients, and both class I/II in 6 patients. Specificities of class II DSAs were DQB1 in 22 patients (85%), DQA1 in 10 patients (39%), DRB1/3/4/5 in 7 patients (27%), and DPB1 in 1 patient (4%). Conclusions HLA-DQ alpha DSA was detected in a substantial percent of DSA positive renal transplant patients, thus DQA1 donor typing is important in renal post-transplant monitoring.