Late Graft Rejection in Association With T-Large Granular Lymphocyte Expansion of Recipient Origin After Human...

Large granular lymphocyte (LGL) expansion occasionally occurs after allogeneic stem cell transplantation (allo-SCT), and is thought to be a good prognostic sign that is associated with a lower relapse rate. However, there have been no reports of late graft failure (LGF) due to graft rejection in association with oligoclonal LGL expansion. We herein report a case of LGF associated with the transient expansion of recipient-derived T-LGL after allo-SCT.

A 65-year-old man underwent peripheral blood stem cell transplantation (PBSCT) from his human leukocyte antigen (HLA)-haploidentical son for the treatment of acute myeloid leukemia, which had evolved from a myelodysplastic syndrome (MDS). Neutrophil engraftment occurred on day 20. A chimerism analysis on day 29 showed both granulocytes and mononuclear cells in the peripheral blood to be completely of donor origin. However, his neutrophil count gradually decreased and a chimerism analysis on day 61 showed that 84% of the patient's T cells were of recipient origin while the granulocytes were 100% donor-derived. His LGLs rapidly increased to 4.01 × 10⁹/L on day 113 and decreased thereafter. The percentage of donor cells in his granulocytes gradually decreased, and the patient's leukocytes were completely replaced by recipient cells on day 177.

The clinical course suggests that the expansion of recipient-derived T-LGLs after allo-SCT can be a sign of graft rejection. Early intervention may be needed if the LGL expansion is recipient-derived.