5-OR

Abstract

Aim Recent literature suggests that the presence of donor specific anti-HLA antibodies (DSA) may result in delayed or failure to engraft in bone marrow transplantation (BMT). We present a case of successful BMT in the presence of DSA. Methods Case: 54 year old female with therapy related myelodysplastic syndrome and excess blast for BMT. Patient had no matched siblings and NMDP search identified two donors that were 9/10 match at HLA-A, B,C,DRB1 and DQB1. She is highly alloimmunized and serum demonstrated multiple anti-HLA antibodies including anti-HLA-DP antibodies using single antigen beads (SAB, One Lambda). Thus both the donors were also typed for HLA-DPB1. Selected donor was mismatched at HLA-DQB1 and DPB1. [ Table 1 ] Results Pre-transplant (Tx) SAB revealed presence of DSA to HLA-DPB1*04:02 that demonstrated a prozone phenomenon and B-cell flow crossmatch with the donor cells was positive with mean channel shift=346 (cutoff : >106). Clinical outcome: Plasmapheresis one month before transplant failed to significantly reduce DSA. As there were no additional therapy options, after discussing the relevant risks with the patient we proceeded to Tx. Pre-Tx conditioning included plasmapheresis on days −3 to 0. Patient engrafted by day 15 post-Tx. To characterize the DSA, patient samples were tested for C1q and IgG subtypes. Results demonstrate a post-Tx decrease in DSA and it is predominantly IgG1 subtype and C1q positive. [ Table 2 ] Conclusions Successful BMT is possible in the presence of DSA. This case demonstrates that mere presence of DSA may not be the cause of delayed or failure to engraft in BMT. Evaluation of additional mechanisms and hypothesis is required. Chen: Thermo Fisher Scientific: Employee. Lee: Thermo Fisher Scientific: Employee.