[Induction of efficient T-cell immunity against autologous leukemia cells by dendritic cells pulsed with the leukemia cell total RNA].
OBJECTIVE
To assess the feasibility and efficiency of eliciting leukemia-specific T cell responses in acute myeloid leukemia patients in complete remission (AML-CR) in vitro by dendritic cells (DC) pulsed with the leukemia cells total RNA.


METHODS
The immature DCs were generated from the adherent bone marrow mononuclear cell in vitro in the presence of combined cytokines (GM-CSF 100 ng/ml, IL-4 500 U/ml), and pulsed with total RNA isolated from autologous leukemic cells by cationic lipid 1,2-dioleoyloxy-3-trimethyl ammonium propane (DOTAP) at day 5 of culture. Then the cells were incubated for another 24 h in a medium containing 10 ng/ml of TNF-alpha for maturation of DC. After the total 7 days culture, the cells were harvested as the mRNA-DC and the expression of mature DC markers were determined by FACS. The proliferative capacity of T cell activated by mRNA-DC was determined by MTT assay. Meanwhile, the mRNA-DC was co-cultured with T lymphocytes at a ratio of 1:3 for 7 days. The activated T lymphocytes were harvested, the secretion of IFN-gamma was determined by ELISPOT assay, and the cytotoxicity was analyzed in vitro by LDH release assay.


RESULTS
After culture, the BMMNC from 14 AML-CR patients developed morphologic and phenotypic characteristics of mature DC. At a stimulator/reactor ratio of 1:16, auto-T lymphocytes primed with mRNA-DC exhibited significant proliferative activity compared with T lymphocyte primed with non-pulsed DC [(36.84 +/- 5.68)% vs (12.20 +/- 3.16)%, (P < 0.05)]. An expansion of mRNA reacted T cell secreting IFN-gamma could be observed on ELISPOT assay. At an effector/target ratio of 20:1, the auto-T lymphocytes primed with mRNA-DC exhibited significant killing activity to auto-AML cells (45.46 +/- 6.34 )% as compared with that stimulated by IL-2 alone (13.26 +/- 2.28)% or primed by non-pulsed DC (12.32 +/- 1.32)% (P < 0.05).


CONCLUSIONS
Immunization with DC-leukemia cell RNA vaccines may be a simple, rapid and potent approach to elicitation of T cell-mediated anti-leukemia immunity.
Ge
Wei
W
The State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, CAMS and PUMC, Tianjin, China.
You
Sheng-Guo
SG
Wang
Ya-Fei
YF
Li
Chang-Hong
CH
Liu
Xiao-Fan
XF
He
Xue-Peng
XP
Ma
Shuang
S
Qiu
Lugui
L
D000293:Adolescent; D000328:Adult; D002450:Cell Communication; D002478:Cells, Cultured; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology*; D005260:Female; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012313:RNA / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000276:immunology*
D012313:RNA