DynaChip Anti-HLA Antibody Analysis In Sera of Patients Following Allo-HSCT From HLA-Mismatched Unrelated Donors.

Anti-HLA antibodies constitute potentially important factor that may influence outcomes of HLA-mismatched allogeneic hematopoietic stem cell transplantation (allo-HSCT). The rationale of this study was to detect presence of anti-HLA antibodies in recipients of allo-HSCT from HLA-mismatched unrelated donors.

Anti-HLA-A,B,C,DR,DQ,DP antibodies were identified in sera collected from 46 recipients of allo-HSCT from HLA-mismatched unrelated donors. Sera were collected between 1 month and 5.5 years after allo-HSCT, and additionally before allo-HSCT in 17 pts. We have used microchips spotted with purified HLA class I and HLA class II antigens to allow binding of anti-HLA antibodies present in tested sera to the surface of the microchip, pre-optimised reagents and DynaChip Processor (Dynal Invitrogen Corporation) for assay processing, data acquisition and analysis.

Antibodies against HLA class I, II or I and II were detected in 15%, 11% and 35% of pts whereas no antibodies were detected in 39% of patients. Antibodies were directed against HLA-A, B, C, DR and DQ in 37%, 46%, 35%, 48% and 35% of pts, respectively. Pre-transplant anti-HLA antibodies have been detected in 7 pts (41%) out of 17 tested before allo-HSCT. In this group percent of Panel Reactive Antibodies (% PRA) increased following allo-HSCT in 3 pts and decreased in 4. In 5 out of 10 remaining pts without pre-transplant antibodies, %PRA increased post-transplant. DynaChip software allowed to define specificities of HLA-A,B,C,DR and DQ antibodies on low and high resolution levels. The specificity of antigens that masked results of antibody identification has been also defined in 2 pts. At this stage we did not define exactly whether detected anti-HLA antibodies were donor-specific. Cross-reactive groups (CREG's) analysis has been also used to compare antibodies’ reactivity. Anti-HLA-DP antibodies were not detected in the examined group of transplanted patients.

Presented preliminary study results indicate, that anti-HLA antibodies can appear post-transplant in mismatched allo-HSCT recipients. Further analysis aiming to evaluate their influence on transplant outcomes is ongoing. We intend to extend the search for anti-HLA antibodies with use of Luminex LabScreen method.

No relevant conflicts of interest to declare.