Jm. Specht et al., DENDRITIC CELLS RETROVIRALLY TRANSDUCED WITH A MODEL ANTIGEN GENE ARETHERAPEUTICALLY EFFECTIVE AGAINST ESTABLISHED PULMONARY METASTASES, The Journal of experimental medicine, 186(8), 1997, pp. 1213-1221
Dendritic cells (DCs) are bone marrow-derived leukocytes that function
as potent antigen presenting cells capable of initiating T cell-depen
dent responses from quiescent lymphocytes. DC pulsed with tumor-associ
ated antigen (TAA) peptide or protein have recently been demonstrated
to elicit antigen-specific protective antitumor immunity in a number o
f murine models. Transduction of DCs with TAA genes may allow stable,
prolonged antigen expression as well as the potential for presentation
of multiple, or unidentified, epitopes in association with major hist
ocompatibility complex class I and/or class II molecules. To evaluate
the potential efficacy of retrovirally transduced DCs, bone marrow cel
ls harvested from BALB/c mice were transduced with either a model anti
gen gene encoding beta-galactosidase (beta-gal) or a control gene enco
ding rat HER-2/neu (Neu) by coculture with irradiated ecotropic retrov
iral producer lines. Bone marrow cells were differentiated into DC in
vitro using granulocyte/macrophage colony-stimulating factor and inter
leukin-4. After 7 d in culture, cells were 45-78% double positive for
DC phenotypic cell surface markers by FACS(C) analysis, and DC transdu
ced with beta-gal were 41-72% positive for beta-gal expression by X-ga
l staining. In addition, coculture of beta-gal transduced DC with a be
ta-gal-specific T cell line (CTLx) resulted in the production of large
amounts of interferon-gamma, demonstrating that transduced DCs could
process and present endogenously expressed beta-gal. DC transduced wit
h beta-gal and control rat HER-2/neu were then used to treat 3-d lung
metastases in mice bearing an experimental murine tumor CT26.CL25, exp
ressing the model antigen, beta-gal. Treatment with beta-gal-transduce
d DC significantly reduced the number of pulmonary metastatic nodules
compared with treatment with Hank's balanced salt solution or DCs tran
sduced with rat HER-2/neu. In addition, immunization with beta-gal-tra
nsduced DCs resulted in the generation of antigen-specific cytotoxic T
lymphocytes (CTLs), which were significantly more reactive against re
levant tumor targets than CTLs generated from mice immunized with DCs
pulsed with the L-d-restricted beta-gal peptide. The results observed
in this rapidly lethal tumor model suggest that DCs transduced with TA
A may be a useful treatment modality in tumor immunotherapy.