Long-term immune recovery after CD34+ immunoselected and unselected peripheral blood progenitor cell transplantation: a case-control study.

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.