Desensitization for hematopoietic stem cell transplantation: Case report

Resumen

Purpose: The presence of anti-human leukocyte antigen (HLA) antibodies has been correlated with graft failure in organ and tissue transplantation, demonstrating the importance of screening for antibodies before transplant. The purpose of the study is to report the desensitization protocol used for pre-transplant treatment of hematopoietic stem cells (HSCT) in previously sensitized patients. Methods: Case report of two cases of patient with high HLA specific antibody titers submitted to a desensitization protocol for allogeneic HSCT at a reference center for HSCT in Southern Brazil. The desensitization protocol consisted of rituximab and plasma exchange (PLEX) three times a week, with human immunoglobulin replacement (IVIg) after each session. Results: The first patient had a panel-reactive antibodies class I (PRA-I) score of 97%, with 20 highly reactive antibodies and no detectable DSA. The decision was made to attempt antibody desensitization to facilitate platelet transfusion during HSCT, which was completed after nine sessions of plasma exchange (PLEX), resulting in a reduction in PRA-I of 71%, and no highly reactive antibodies were detected. The second patient presented a PRA-I score of 53% and PRA class II (PRA-II) of 99%, including 16 highly reactive antibodies and DSA against both possible donors. After the ninth session of PLEX, treatment was intensified and continued until the end of the 19 sessions. At the end of the protocol, PRA-I and PRA-II had been reduced to 0% and 87% respectively, with persistent presence of only two highly reactive antibodies and no detectable DSA. Conclusion: The antibody desensitization and select platelet donor transfusion assured a more appropriate transfusion support to a HLA sensitized patient refractory to platelet transfusion with a matched sibling donor and PRA monitoring being essential for defining the appropriate desensitization regimen to a patient with DSAs and haploidentical donor.