Background Cryopreservation is often used to store cellular therapies, but little is known about how well CD3+ or CD34+ cells tolerate this process. Study Design Viable CD34+ cell recoveries were analyzed from related and unrelated donor G-CSF-mobilized peripheral blood stem cell (PBSC) products and viable CD3+ cell recoveries from G-CSF-mobilized and non-mobilized apheresis products from related and unrelated donors. All products were cryopreserved with 5% dimethyl sulfoxide and 6% pentastarch using a controlled-rate freezer and were stored in liquid nitrogen. Related donor products were cryopreserved immediately after collection and unrelated donor products greater than 12 hours post-collection. Results The post-thaw recovery of CD34+ cells from related donor PBSCs was high (n=86; 97.5±23.1%) and there was no difference in post-thaw CD34+ cell recovery from unrelated donor PBSCs (n=14; 98.8±37.2%; p=0.863). In related donor lymphocyte products the post-thaw CD3+ cell recovery (n=48, 90.7±21.4%) was greater than that of unrelated donor products (n=14, 66.6±35.8%, p=0.00251). All unrelated donor lymphocyte products were from G-CSF mobilized products, while most related donor lymphocyte products were from non-mobilized products. A comparison of the CD3+ cell recovery from related donor G-CSF-mobilized products (n=19, 85.0±29.2%) with that of unrelated donor products found no significant difference (p=0.137). CONCLUSIONS The post-thaw recovery of CD34+ cells was high in both related and unrelated donor products, but the recovery of CD3+ cells in unrelated donor G-CSF-mobilized products was lower. G-CSF-mobilized unrelated donor products may contain less CD3+ cells than non-G-CSF exposed products upon thaw and, when indicated, cell doses should be monitored.

Introduction 2.1. The immune system: A brief review 2.1.1. The hematopoietic stem-cell transplant patient: An immunologic alteration 2.1.2. Immune reconstitution in the stem-cell transplant patient: General considerations 2.1.3. Overview of recovery 2.1.4. Specific considerations 2.1.5. Immune reconstitution in the pediatric stem-cell transplant 3. Conclusion 4. Acknowledgment 5. References