CD40 ligand is essential for generation of specific cytotoxic T cell responses in RNA-pulsed dendritic cell immunotherapy.
BACKGROUND
Dendritic cell (DC)-based immunotherapy is a promising form of adjuvant therapy for high-risk tumors. DCs transfected with tumor-associated antigens are capable of stimulating antigen-specific T cells, but cytolytic responses have been disappointing. Activation of DC surface CD40 influences DC cytokine production, particularly that of interleukin (IL)-12, which favors a Th1 (cytotoxic) helper T cell response. This study evaluated the effects of exogenous soluble CD40 ligand (sCD40L) on RNA-transfected DC preparations and their subsequent ability to generate antimelanoma cytolytic T cells.


METHODS
Human monocyte-derived DCs were cultured and transfected with mRNA encoding full-length melanoma-associated antigen, Mart-1, and matured with and without sCD40L. DC IL-12 secretion and the ability to stimulate naïve T cells were assessed by enzyme-linked immunosorbent assay (ELISA), tetramer analysis, Elispot, and (51)Cr release assay.


RESULTS
Mature DCs stimulated with sCD40L secreted higher levels of IL-12 compared with immature DCs and DCs matured without sCD40L (P <.001). DCs treated with sCD40L generated a greater number of antigen-specific T cells (P <.05) by tetramer and Elispot analyses, and yielded specific T cells with significant cytotoxicity against HLA-matched melanoma cell lines.


CONCLUSIONS
CD40L augments DC IL-12 secretion and is essential to potentiate specific antimelanoma cytolytic responses stimulated by the Mart-1 antigen. sCD40L should be considered a crucial adjuvant in DC preparations for RNA-based DC vaccine therapies.
Onaitis
Mark W
MW
Department of Surgery, Duke University and Durham VA Medical Centers, Durham, NC 27710, USA.
Kalady
Matthew F
MF
Emani
Sirisha
S
Abdel-Wahab
Zeinab
Z
Tyler
Douglas S
DS
Pruitt
Scott K
SK
D000951:Antigens, Neoplasm; D023201:CD40 Ligand / Q000494:pharmacology*; D019496:Cancer Vaccines / Q000494:pharmacology; D002478:Cells, Cultured; D016922:Cellular Senescence; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D006801:Humans; D007167:Immunotherapy; D018664:Interleukin-12 / Q000378:metabolism; D058965:MART-1 Antigen; D008545:Melanoma / Q000276:immunology / Q000473:pathology; D009363:Neoplasm Proteins / Q000235:genetics / Q000276:immunology; D012333:RNA, Messenger; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D014162:Transfection
D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D023201:CD40 Ligand; D018664:Interleukin-12