Human monocyte-derived dendritic cells pulsed with wild-type p53 protein efficiently induce CTLs against p53 overexpressing human cancer cells.
OBJECTIVE
Dendritic cells are the most potent antigen-presenting cells for initiating cellular immune responses. Dendritic cells are attractive immunoregulatory cells for cancer immunotherapy, and their efficacy has been investigated in clinical trials. The tumor suppressor gene p53 is pivotal in the regulation of apoptosis, and p53-based immunization is an attractive approach to cancer immunotherapy because of the accumulation of p53 protein in malignant but not in normal cells. It has been shown that dendritic cells transduced with an adenoviral wild-type p53 (wt-p53) construct mediate the antitumor immune responses against p53-overexpressing tumor cells. We examined whether monocyte-derived human dendritic cells pulsed with the purified full-length wt-p53 protein were also capable of inducing the specific antitumor responses against p53-overexpressing tumors in vitro.


METHODS
Immature dendritic cells generated in the presence of interleukin-4 and granulocyte/macrophage colony-stimulating factor from monocytes of HLA-A2- or HLA-A24-positive healthy individuals were pulsed with the purified p53 protein. Uptake of p53 protein by human dendritic cells was assessed by Western blotting and immunohistochemical staining using anti-p53 antibody. Induction of p53-specific CTL response was also evaluated by the cytotoxic assay against p53-overexpressing human tumor cells.


RESULTS
Both Western blot and immunohistochemical analysis showed the accumulation of p53 protein in human immature dendritic cells. T cells obtained from HLA-A2- or HLA-A24-positive healthy donors were stimulated twice with p53 protein-pulsed dendritic cells and then applied to the cytotoxicity assay against p53-overexpressing target cells. The CTL activity was specific for p53-overexpressing tumor cells and MHC class I restricted. Moreover, the CTL activity generated by p53 protein-pulsed dendritic cells was nearly identical with that induced by adenoviral wt-p53-transduced dendritic cells.


CONCLUSIONS
Our results indicate that monocyte-derived human dendritic cells pulsed with the wt-p53 protein could induce the specific antitumor effect against p53-overexpressing tumors and that this in vitro model offers a new and more simple approach to the development of p53-based immunotherapy.
Tokunaga
Naoyuki
N
Division of Surgical Oncology, Department of Surgery, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikata-cho, Okayama 700-8558, Japan.
Murakami
Takayoshi
T
Endo
Yoshikatsu
Y
Nishizaki
Masahiko
M
Kagawa
Shunsuke
S
Tanaka
Noriaki
N
Fujiwara
Toshiyoshi
T
D015703:Antigens, CD / Q000032:analysis; D018122:B7-1 Antigen / Q000032:analysis; D051940:B7-2 Antigen; D002454:Cell Differentiation / Q000276:immunology; D002460:Cell Line; D045744:Cell Line, Tumor; D003601:Cytotoxicity Tests, Immunologic; D003602:Cytotoxicity, Immunologic / Q000276:immunology; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D005434:Flow Cytometry; D005838:Genotype; D006684:HLA-DR Antigens / Q000032:analysis; D006801:Humans; D007136:Immunoglobulins / Q000032:analysis; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000032:analysis; D009000:Monocytes / Q000166:cytology / Q000276:immunology*; D009154:Mutation; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D000097802:CD83 Antigen
D015703:Antigens, CD; D018122:B7-1 Antigen; D051940:B7-2 Antigen; D006684:HLA-DR Antigens; D007136:Immunoglobulins; D008562:Membrane Glycoproteins; D016159:Tumor Suppressor Protein p53; D000097802:CD83 Antigen; C497964:CD86 protein, human