In vitro induction of T cells that are resistant to A2 adenosine receptor-mediated immunosuppression.
OBJECTIVE
The increased levels of extracellular adenosine in inflamed tissues down-regulate activated immune cells via the A(2A) adenosine receptor. This A(2A) adenosine receptor-mediated immunosuppression is a disqualifying obstacle in cancer immunotherapy as it protects cancerous tissues from adoptively transferred anti-tumour T cells. The aim of this study was to test whether the negative selection of T cells will produce T cells that are resistant to inhibition by extracellular adenosine.


METHODS
Cytotoxic T lymphocytes (CTL) were developed by mixed lymphocyte culture in the presence or absence of the adenosine receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA). The sensitivity of CTL to adenosine analogues was characterized by cAMP induction, interferon-gamma production and cytotoxicity.


RESULTS
CTL that could proliferate even in the presence of NECA were less susceptible to inhibition by A(2A) adenosine receptor agonists, as shown by a much smaller accumulation of cAMP and less inhibition of interferon-gamma production compared with control CTL. The successful protocol to produce CTL that are both resistant to adenosine-mediated immunosuppression and maintain strong cytotoxicity and interferon-gamma secretion required NECA to be added only during the expansion stage after the establishment of CTL. In contrast, the priming of resting T cells in the presence of NECA resulted in T cells with impaired effector functions.


CONCLUSIONS
Adenosine-resistant effector T cells were successfully obtained by exposure of activated T cells to NECA. These in vitro studies form the basis for future attempts to produce anti-tumour T cells that are more effective in adoptive immunotherapy.
Ohta
Akio
A
New England Inflammation and Tissue Protection Institute, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA. a.ohta@neu.edu
Kjaergaard
J
J
Sharma
S
S
Mohsin
M
M
Goel
N
N
Madasu
M
M
Fradkov
E
E
Ohta
Akiko
A
Sitkovsky
M
M
D000241:Adenosine / Q000378:metabolism; D058908:Adenosine A2 Receptor Agonists; D019830:Adenosine-5'-(N-ethylcarboxamide) / Q000494:pharmacology; D000818:Animals; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000096:biosynthesis; D003602:Cytotoxicity, Immunologic; D005110:Extracellular Space / Q000378:metabolism; D007108:Immune Tolerance / Q000187:drug effects; D007371:Interferon-gamma / Q000096:biosynthesis; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D043705:Receptor, Adenosine A2A / Q000502:physiology*; D043704:Receptor, Adenosine A2B / Q000502:physiology*; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology* / Q000187:drug effects / Q000276:immunology
D058908:Adenosine A2 Receptor Agonists; D043705:Receptor, Adenosine A2A; D043704:Receptor, Adenosine A2B; D019830:Adenosine-5'-(N-ethylcarboxamide); D007371:Interferon-gamma; D000242:Cyclic AMP; D000241:Adenosine