Optimal Timing for the Collection and In Vitro Expansion of Cytotoxic CD56 + Lymphocytes from Patients Undergoing Autologous Peripheral Blood Stem Cell Transplantation

Abstract

To identify the optimal time for the collection of CD56+ cytotoxic lymphocytes for adoptive immunotherapy in patients undergoing high-dose chemotherapy (HDCT) and peripheral blood stem cell (PBSC) transplantation, 18 breast cancer patients receiving either three cycles of epirubicin/paclitaxel (CT × 3) followed by HDCT and PBSC transplantation (n = 12) or CT×6 (n = 6) were studied. Blood samples were obtained before each CT/HDCT cycle, from PBSC collections, and repeatedly after autografting for up to 12 months. The number of CD56⁺3^- and CD56⁺3⁺ lymphocytes, their in vitro expandability with interleukin-2, and their cytotoxicity against MCF-7 and Daudi cells were analyzed. Six healthy females served as controls. CD56⁺ cell counts in both treatment groups were subnormal but stable during the observation period. The cytotoxicity of the expanded CD56⁺ cells was normal and unaffected by the treatment. The in vitro CD56⁺ cell expandability (controls, 100 ± 31-fold, mean ± SEM) was normal before CT1 and CT2, but reduced in PBSC harvests performed after CT2 and application of G-CSF (21 ± 6-fold; p < 0.01). After PBSC harvesting, the CD56⁺ cell expandability increased to 185 ± 74-fold and 170 ± 69-fold (before CT3 and HDCT). This increase was not observed in those patients who did not undergo PBSC mobilization. Two weeks after autografting, the CD56⁺ cell expandability was minimal(6 ± 1-fold), and recovered to 34 ± 6-fold. Thus, CT, HDCT and autografting do not alter the frequency and inducible cytotoxicity of CD56⁺ cells in breast cancer patients. However, the proliferative capacity of CD56⁺ cells obtained from PBSC harvests and after autografting is impaired. Therefore, instead of the PBSC graft, maximally expandable CD56⁺ cells obtained at least 1 week after PBSC collection should be considered for adoptive immunotherapy after PBSC autografting.