Indoleamine-2,3-dioxygenase enzyme expression and activity in polarized dendritic cells.
OBJECTIVE
Polarized mature dendritic cells (DC) can activate cytolytic T-lymphocyte (CTL) responses and may be a more effective clinical strategy in DC-based cancer vaccines. A subset of mature DC can down-regulate the T-cell immune response through expression of indoleamine-2,3-dioxygenase (IDO). We determined whether polarizing DC ex vivo increased IDO expression and activity.


METHODS
Peripheral blood monocytes from healthy volunteers were cultured ex vivo in polarizing and non-polarizing culture conditions. DC IDO expression was detected by Western blot. IDO enzyme activity was determined by high-performance liquid chromatography (HPLC) measurement of kynurenine (K) and tryptophan (T) concentrations in culture supernatants.


RESULTS
IDO protein was markedly increased in DC after polarization (median 1222.4%, range 331.5-2113.3%) versus non-polarized DC (median 28.3%, range 3.7-119.8%; P=0.04). The median K/T ratio was significantly higher in polarized DC versus non-polarized DC (6.34, range 6.02-6.65, versus 0.047, range 0.004-0.541; P=0.04). IDO protein expression correlated with enzyme activity (r=0.80, P=0.002).


CONCLUSIONS
DC polarizing culture conditions increased expression of IDO protein and IDO enzyme activity. DC culture and maturation methodologies may impact the effectiveness of adoptive DC therapy.
Wolf
Benita
B
Medical Oncology Immunotherapy Group, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire 03756, USA.
Posnick
David
D
Fisher
Jan L
JL
Lewis
Lionel D
LD
Ernstoff
Marc S
MS
D015153:Blotting, Western; D016764:Cell Polarity / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology; D003713:Dendritic Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D003720:Densitometry; D006801:Humans; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000378:metabolism*; D008297:Male; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism
D016207:Cytokines; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase