Leukoreduction system chambers are a reliable cellular source for the manufacturing of T-cell therapeutics

Following solid organ or hematopoietic cell transplantation, refractory opportunistic viral reactivations are a significant cause of morbidity and mortality but can effectively be controlled by virus-specific T-cell transfer. Among effective and safe strategies is the use of "third-party" (neither from the transplant donor nor recipient) virus-specific T cells that can be manufactured from healthy donors and used as "off-the-shelf" therapies. Leukoreduction system chambers (LRSCs), recovered after routine plateletpheresis, were evaluated as a potential source of peripheral blood mononuclear cells (PBMCs) for the manufacturing of clinical-scale virus-specific T cell.

PBMCs from the same donors obtained either from LRSCs or peripheral blood were compared, focusing on T-cell function and phenotype as well as the potential to generate cytomegalovirus (CMV)-specific T-cell lines from both CMV seropositive and seronegative donors.

PBMCs from both sources were comparable except for a transient downregulation of CD62L expression on freshly extracted PBMCs from LRSCs. Both nonspecific stimulation using anti-CD3/CD28 antibodies and CMV peptides revealed that LRSCs or blood T cells were equivalent in terms of expansion, differentiation, and function. Moreover, PBMCs from LRSCs can be used to generate autologous monocyte-derived dendritic cells to prime and expand CMV-specific T cells from seronegative donors.

LRSCs are a reliable source of PBMCs for the generation of virus-specific T cells for immunotherapy. These findings have implications for the development of third-party therapeutic T-cell products from well-characterized blood product donors.