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Functional heterogeneity of cytotoxic T cells and tumor resistance to cytotoxic hits limit anti‐tumor activity in vivo
Author(s) -
Khazen Roxana,
Cazaux Marine,
Lemaître Fabrice,
Corre Beatrice,
Garcia Zacarias,
Bousso Philippe
Publication year - 2021
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2020106658
Subject(s) - cytotoxic t cell , biology , in vivo , ctl* , cancer research , tumor microenvironment , immunology , in vitro , microbiology and biotechnology , tumor cells , biochemistry
Abstract Cytotoxic T cells (CTLs) can eliminate tumor cells through the delivery of lethal hits, but the actual efficiency of this process in the tumor microenvironment is unclear. Here, we visualized the capacity of single CTLs to attack tumor cells in vitro and in vivo using genetically encoded reporters that monitor cell damage and apoptosis. Using two distinct malignant B‐cell lines, we found that the majority of cytotoxic hits delivered by CTLs in vitro were sublethal despite proper immunological synapse formation, and associated with reversible calcium elevation and membrane damage in the targets. Through intravital imaging in the bone marrow, we established that the majority of CTL interactions with lymphoma B cells were either unproductive or sublethal. Functional heterogeneity of CTLs contributed to diverse outcomes during CTL–tumor contacts in vivo . In the therapeutic settings of anti‐CD19 CAR T cells, the majority of CAR T cell–tumor interactions were also not associated with lethal hit delivery. Thus, differences in CTL lytic potential together with tumor cell resistance to cytotoxic hits represent two important bottlenecks for anti‐tumor responses in vivo .