Progressive multifocal leukoencephalopathy after autologous peripheral blood stem cell transplantation in a patient with multiple myeloma treated with combination therapy.
BACKGROUND AND OBJECTIVE CD34+ stem cell selection induces extensive T-cell depletion as a consequence of ex vivo manipulation. The impact of T-cell depletion on long-term immunologic recovery after autologous CD34+ peripheral blood progenitor cell transplantation (CD34+ PBPCT) is not well characterized. We compared the long term immunologic recovery in two groups of patients submitted to CD34+ PBPCT or unselected autologous peripheral blood progenitor cell transplantation (uPBPCT). DESIGN AND METHODS Eight patients in both groups were closely matched for diagnosis, age, disease status at transplantation and conditioning regimen and lymphocyte phenotype was prospectively evaluated during long-term post-transplantation follow-up. RESULTS At a median of 18 months after transplantation, CD3+ lymphocyte subset remained below the normal range in both groups. CD19+ B lymphocytes subset after CD34+ PBPCT was within the normal range in both groups. CD4+ lymphocytes were depressed while the CD8+ lymphocyte subset was increased in group A and in the normal range in group B. As a result, inversion of CD4/CD8 ratio was documented in both groups. T-activated lymphocytes (CD3DR+) and natural killer (CD16/56+) cells were increased in both groups. INTERPRETATION AND CONCLUSIONS Long-term immune recovery appears to be unaffected by extensive ex vivo manipulation in this adult population when compared to recovery after unmanipulated PBPCT. CD34+ selection, although causes an extensive depletion of T lymphocytes in the graft does not represent a risk factor for delayed CD4+ recovery late after transplantation. Elevated numbers of NK cells and activated T-cells, which have antineoplastic activity, are maintained late after autologous CD34+ transplantation.