Early-onset de novo donor-specific anti-HLA antibodies may contribute to poor graft function following haploidentical transplantation for myelodysplastic syndrome: a rare case presentation.

In haploidentical hematopoietic stem cell transplantation, preexisting donor-specific anti-HLA antibodies (DSAs) in recipients have been associated with graft rejection, poor graft function (PGF), and unfavorable clinical outcomes, with relatively well-established consensus strategies for its management. However, reports on the emergence of de novo DSAs after transplantation and the corresponding therapeutic approaches remain limited. Here, we describe a case of a 14-year-old patient with myelodysplastic syndrome who developed de novo DSAs as early as day 15 post-transplantation, with a peak mean fluorescence intensity of 12,280, which was associated with PGF. To reduce DSA levels, plasma exchange combined with intravenous immunoglobulin and rituximab was administered, followed by a series of interventions including mesenchymal stem cell infusion. These measures facilitated graft function recovery, controlled transplant-related complications, and ultimately led to successful engraftment.