Importance of early immune recovery after autologous hematopoietic cell transplantation in lymphoma patients.

Lymphomas constitute the second most common indication for autologous hematopoietic cell transplantation (AHCT). Graft infusion is followed by a rapid hematological recovery and slower immune recovery. The number of natural killer cells and CD3+ T lymphocytes achieve normal counts usually within a month, whereas the recovery of CD3+CD4+ T lymphocytes is much slower. Early immune recovery is usually defined as the absolute lymphocyte count (ALC) ≥0.5 × 109/L, which has been associated with improved progression-free and even overall survival. Several factors have been associated with early immune recovery, including higher infused lymphocyte and CD34+ cell doses, both of which are affected by the choice of mobilization. This review summarizes the clinical importance of early immune recovery for long-term success of AHCT in lymphomas. Factors known to affect early immune recovery are discussed and suggestions made how to improve mobilization and collection processes to optimize immune recovery and post-transplant outcomes.