Single-cell imaging of CAR T cell activity in vivo reveals extensive functional and anatomical heterogeneity

J Exp Med. 2019 May 6;216(5):1038-1049. doi: 10.1084/jem.20182375. Epub 2019 Apr 1.


CAR T cells represent a potentially curative strategy for B cell malignancies. However, the outcome and dynamics of CAR T cell interactions in distinct anatomical sites are poorly understood. Using intravital imaging, we tracked interactions established by anti-CD19 CAR T cells in B cell lymphoma-bearing mice. Circulating targets trapped CAR T cells in the lungs, reducing their access to lymphoid organs. In the bone marrow, tumor apoptosis was largely due to CAR T cells that engaged, killed, and detached from their targets within 25 min. Notably, not all CAR T cell contacts elicited calcium signaling or killing while interacting with tumors, uncovering extensive functional heterogeneity. Mathematical modeling revealed that direct killing was sufficient for tumor regression. Finally, antigen-loss variants emerged in the bone marrow, but not in lymph nodes, where CAR T cell cytotoxic activity was reduced. Our results identify a previously unappreciated level of diversity in the outcomes of CAR T cell interactions in vivo, with important clinical implications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD19 / metabolism
  • Apoptosis
  • Cell Line, Tumor
  • Immunotherapy, Adoptive / methods*
  • Intravital Microscopy / methods*
  • Lung / metabolism
  • Lymphoma, B-Cell / pathology
  • Lymphoma, B-Cell / therapy*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Models, Animal
  • Models, Theoretical
  • Receptors, Chimeric Antigen / metabolism*
  • Recurrence
  • Single-Cell Analysis / methods*
  • T-Lymphocytes / metabolism*


  • Antigens, CD19
  • CD19 antigen, mouse
  • Receptors, Chimeric Antigen