DONOR LYMPHOCYTE INFUSION FOR POST-TRANSPLANT NEUTROPENIA ACCOMPANIED BY MIXED CHIMERISM IN A PATIENT WITH IDIOPATHIC NEUTROPENIA WHICH LATER TRANSFORMED INTO ACUTE MYELOID LEUKEMIA

Donor lymphocyte infusions (DLI) are often used to convert mixed to full donor chimerism. Here, we present the case of a patient who developed agranulocytosis accompanied by mixed chimerism following allogeneic peripheral blood stem cell transplantation (PBSCT) and then responded to DLI. In 1998, a 59-year-old man presented with unexplained neutropenia. Although immunosuppressive therapies were ineffective, his neutropenia responded moderately to high-dose G-CSF, with which he was treated for 5 years. In 2003, transformation to acute myeloid leukemia occured. He received allogeneic PBSCT from an HLA-identical sister. The conditioning regimen consisted of busulfan and cyclophosphamide. Engraftment of neutrophils was documented on day 24 after PBSCT. However, on day 53, severe neutropenia recurred. Bone marrow examination revealed marked cytolysis and a specific decrease in myeloid lineage cells. T-cell chimerism was assessed against peripheral blood mononuclear cells by PCR analysis of short tandem repeat loci, and the presence of recipient CD3-positive T cells was demonstrated (recipient type: 48.3%). DLI was performed to convert mixed to full donor chimerism. After one course of DLI (CD3-positive dose of 1×107/kg of recipient body weight), his neutropenia improved. However, the patient developed idiopathic pneumonia syndrome concurrent with neutrophil recovery, and he died of respiratory failure 92 days after PBSCT. This case emphasizes the importance of recipient cells in transplant-associated immune neutropenia, and the effectiveness of DLI in converting mixed to full donor chimerism.