Cell density plays a critical role in ex vivo expansion of T cells for adoptive immunotherapy

J Biomed Biotechnol. 2010;2010:386545. doi: 10.1155/2010/386545. Epub 2010 Jun 30.


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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Apoptosis
  • Autocrine Communication / immunology
  • CD28 Antigens / metabolism
  • Catalase / metabolism
  • Cell Count
  • Cell Lineage
  • Cell Proliferation
  • Culture Media, Conditioned
  • Humans
  • Immunotherapy, Adoptive*
  • Lymphocyte Activation / immunology
  • Reactive Oxygen Species / metabolism
  • Solubility
  • T-Lymphocytes / cytology*
  • T-Lymphocytes / enzymology
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / metabolism


  • CD28 Antigens
  • Culture Media, Conditioned
  • Reactive Oxygen Species
  • Catalase