Interleukin-12 production by leukemia-derived dendritic cells counteracts the inhibitory effect of leukemic microenvironment on T cells.
OBJECTIVE
Acute myeloid leukemia (AML) cells are poorly immunogenic and inhibit T-cell function. AML-derived dendritic cells (AML-DCs) have better antigen-presentation capacity than undifferentiated leukemic blasts, but may not be fully competent to stimulate T cells previously inhibited by leukemic cells.


METHODS
AML-DCs were generated from AML cells and used to stimulate proliferation and cytokine production by T cells previously inhibited by AML cells. AML-DCs were also transfected with interleukin (IL)-12 gene by the nonviral method, nucleofection.


RESULTS
Mature AML-DCs stimulated naive and, to a lesser extent, leukemic cell (LC)-cultured T cells more efficiently than their immature counterparts and their activity was mediated by IL-12. AML-DCs generated from CD14(-) AML samples (which represent 80% of total AML patients) were defective in IL-12 production and T-cell activation. Addition of exogenous IL-12 to LC-cultured T cells stimulated by CD14(-)-derived AML-DCs restored optimal interferon-gamma (IFN-gamma) production and Th1 skewing. IL-12 gene-nucleofected AML-DCs derived from CD14(-) cells produced significant amounts of IL-12, maintained leukemia-specific karyotype, DC-like phenotype, and function. When stimulated by IL-12-gene transduced CD14(-)-derived AML-DCs, LC-cultured T cells produced higher concentrations of IFN-gamma, thus maintaining a Th1 cytokine profile.


CONCLUSIONS
IL-12 produced by AML-DCs plays a critical role in counteracting the inhibitory activity of LCs on T-cell function. IL-12 gene can be successfully expressed into AML-DCs defective in endogenous IL-12 production by using a novel nonviral method that does not modify their phenotypical, cytogenetic, and functional features. Genetically modified AML-DCs restore a near normal T-cell function.
Curti
Antonio
A
Institute of Hematology and Medical Oncology L. & A. Seràgnoli, University of Bologna and Stem Cell Center, S. Orsola-Malpighi Hospital, Italy. acurti@alma.unibo.it
Pandolfi
Simona
S
Aluigi
Michela
M
Isidori
Alessandro
A
Alessandrini
Isabella
I
Chiodoni
Claudia
C
Testoni
Nicoletta
N
Colombo
Mario P
MP
Baccarani
Michele
M
Lemoli
Roberto M
RM
D000328:Adult; D000368:Aged; D000938:Antigen-Presenting Cells / Q000276:immunology; D018920:Coculture Techniques; D016207:Cytokines / Q000096:biosynthesis; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000235:genetics* / Q000494:pharmacology*; D053765:Interleukin-12 Subunit p35; D053762:Interleukin-12 Subunit p40; D007951:Leukemia, Myeloid / Q000276:immunology* / Q000473:pathology / Q000628:therapy; D008213:Lymphocyte Activation / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D021122:Protein Subunits / Q000235:genetics / Q000494:pharmacology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology; D014161:Transduction, Genetic
D016207:Cytokines; C508858:IL12A protein, human; D053765:Interleukin-12 Subunit p35; D053762:Interleukin-12 Subunit p40; D021122:Protein Subunits; D018664:Interleukin-12; D007371:Interferon-gamma