title: Cell density plays a critical role in ex vivo expansion of T cells for adoptive immunotherapy.
abstract: The successful ex vivo expansion of a large numbers of T cells is a prerequisite for adoptive immunotherapy. In this study, we found that cell density had important effects on the process of expansion of T cells in vitro. Resting T cells were activated to expand at high cell density but failed to be activated at low cell density. Activated T cells (ATCs) expanded rapidly at high cell density but underwent apoptosis at low cell density. Our studies indicated that low-cell-density related ATC death is mediated by oxidative stress. Antioxidants N-acetylcysteine, catalase, and albumin suppressed elevated reactive oxygen species (ROS) levels in low-density cultures and protected ATCs from apoptosis. The viability of ATCs at low density was preserved by conditioned medium from high-density cultures of ATCs in which the autocrine survival factor was identified as catalase. We also found that costimulatory signal CD28 increases T cell activation at lower cell density, paralleled by an increase in catalase secretion. Our findings highlight the importance of cell density in T cell activation, proliferation, survival and apoptosis and support the importance of maintaining T cells at high density for their successful expansion in vitro.
authors.affiliation: Biotherapeutics Development Laboratory, Roger Williams Medical Center, Boston University School of Medicine, Providence, RI 02908, USA. qma@rwmc.org
authors.forename: Qiangzhong
authors.initials: Q
authors.lastname: Ma
authors.forename: Yawen
authors.initials: Y
authors.lastname: Wang
authors.forename: Agnes Shuk-Yee
authors.initials: AS
authors.lastname: Lo
authors.forename: Erica M
authors.initials: EM
authors.lastname: Gomes
authors.forename: Richard P
authors.initials: RP
authors.lastname: Junghans
mesh_terms: D000328:Adult; D017209:Apoptosis; D019898:Autocrine Communication / Q000276:immunology; D018106:CD28 Antigens / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002452:Cell Count; D019070:Cell Lineage; D049109:Cell Proliferation; D017077:Culture Media, Conditioned; D006801:Humans; D016219:Immunotherapy, Adoptive; D008213:Lymphocyte Activation / Q000276:immunology; D017382:Reactive Oxygen Species / Q000378:metabolism; D012995:Solubility; D013601:T-Lymphocytes / Q000166:cytology* / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism
chemical_list: D018106:CD28 Antigens; D017077:Culture Media, Conditioned; D017382:Reactive Oxygen Species; D002374:Catalase