P145 The presence of HLA-IgM donor specific antibodies and possible association with antibody mediated rejection

Abstract

Aim The significance of HLA IgG antibodies in antibody mediated rejection (AMR) is well documented however the effect of HLA IgM donor specific antibodies (DSA) is relatively unknown. HLA IgM antibodies detected in crossmatching are often autoantibodies, however since the availability of beads conjugated with HLA antigens, the detection of HLA IgM antibodies is possible. Our laboratory does not routinely test for HLA IgM antibodies, but we report 4 separate cases which proceeded to transplant with no HLA IgG DSA present, however AMR resulted in graft loss in 3 cases. Method Investigations as a result of reported graft rejection were performed on both pre and post-transplant serum for the presence of HLA IgG and IgM DSA using One Lambda Labscreen Single antigen kits as per request from clinical units. Flow and Complement dependent cytotoxicity (CDC) crossmatches prospective and retrospectively were also reviewed. Results For all 4 recipients tested, we identified HLA IgM DSA pre- and post-transplant none of which were identified prior to transplant. All patients were HLA IgG DSA negative. Graft loss was observed in 3 of 4 patients and CDC and Flow crossmatches (IgG) were negative [Table 1]. Conclusions HLA IgM antibody testing is not routinely performed for patients prior to transplant. As a consequence potential IgM antibodies are not investigated until after graft rejection has already occurred. Note: Australian and state governments fund the Australian Red Cross Blood Service for the provision of blood, blood products and transplantation services to the Australian community.