Blood graft lymphocyte subsets after plerixafor injection in non-Hodgkin's lymphoma patients mobilizing poorly with chemotherapy plus granulocyte-colony-stimulating factor

BACKGROUND: A combination of chemotherapy plus granulocytecolony-stimulating factor (G-CSF) (chemomobilization) is commonly used to mobilize CD34+ cells to circulation. Plerixafor, a chemokine CXCR4 antagonist, increases the mobilization of CD34+ cells and may also have effect on graft composition. STUDY DESIGN AND METHODS: We have analyzed lymphocyte subsets in grafts collected on the next morning after plerixafor injection in 13 chemomobilized patients with non-Hodgkin's lymphoma (NHL) mobilizing poorly. As controls we had the first leukapheresis products from 11 NHL patients mobilized with chemotherapy plus G-CSF. The analyses were performed from cryopreserved apheresis products. RESULTS: The median counts of both total CD3+ T cells and natural killer (NK) cells (CD3CD16/56+) in the graft were significantly higher in plerixafor-treated group compared to the control group. Both helper T-lymphocytes (CD3+CD4+) and suppressor T-lymphocytes (CD3+CD8+) were significantly increased in the plerixafor-treated group so that CD4+/CD8+ ratio in the graft did not differ between the groups. CD19+ cells were evident only at very small amounts in few patients in both groups, and the CD34+ cell content of the graft did not differ between the groups. Engraftment after high-dose therapy was comparable between the groups. CONCLUSION: Plerixafor added to chemomobilization in poor mobilizers seems to mobilize more T cells and NK cells than chemomobilization. Larger patient numbers and longer follow-up is needed in regard to evaluate posttransplant complications and risk of relapse in patients receiving plerixafor due to poor mobilization.