Red blood cell arginase suppresses Jurkat (T cell) proliferation by depleting arginine.
BACKGROUND
Transfusion of packed red blood cells (PRBC) suppresses immunity, but the mechanisms are incompletely understood. PRBCs contain arginase, an enzyme which converts arginine to ornithine and depletes arginine in vitro. Arginine depletion suppresses proliferation of Jurkat T cells in other models. We hypothesize that PRBC arginase-mediated arginine depletion will suppress proliferation of T cells.


METHODS
A transfusion model was designed adding PRBC to culture RPMI media with or without an irreversible arginase blocker (nor-NOHA), incubating for 6-48 hours and then removing the PRBCs. Amino acid concentrations in the media were measured using liquid chromatography mass spectrometry. T cells were then added to the pre-conditioned media, cultured for 24 hours, and proliferation was measured.


RESULTS
PRBC depleted arginine significantly and increased ornithine in media compared to baseline PRBC treated wells and significantly decreased T cell proliferation. These effects were enhanced with volume of PRBC exposure. Nor-NOHA inhibition of arginase restored T cell proliferation in PRBC treated cultures.


CONCLUSIONS
Jurkat T cell proliferation was impaired by PRBC in clinically relevant volumes. The mechanism influencing T cell impairment appears to result from arginine depletion by arginase. Arginine depletion by PRBC arginase may be a novel mechanism for immunosuppression after transfusion.
Bernard
Andrew
A
Trauma/Critical Care Research Program, Department of Surgery, University of Kentucky College of Medicine, Lexington, Kentucky, USA.
Kasten
Michael
M
Meier
Cindy
C
Manning
Erin
E
Freeman
Stephanie
S
Adams
Will
W
Chang
Phillip
P
Boulanger
Bernard
B
Kearney
Paul
P
D000017:ABO Blood-Group System; D001119:Arginase / Q000097:blood* / Q000302:isolation & purification / Q000494:pharmacology*; D001120:Arginine / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects*; D045744:Cell Line, Tumor; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D019169:Jurkat Cells; D007700:Kinetics; D009952:Ornithine / Q000378:metabolism
D000017:ABO Blood-Group System; D001120:Arginine; D009952:Ornithine; D001119:Arginase