ABSTRACT
OBJECTIVE@#To assess the effect of tumor cell lysate (TCL) with low high-mobility group B1 (HMGB1) content for enhancing immune responses of dendritic cells (DCs) against lung cancer.@*METHODS@#TCLs with low HMGB1 content (LH-TCL) and normal HMGB1 content (NH-TCL) were prepared using Lewis lung cancer (LLC) cells in which HMGB1 was inhibited with 30 nmol/L glycyrrhizic acid (GA) and using LLC cells without GA treatment, respectively. Cultured mouse DCs were exposed to different doses of NH-TCL and LH-TCL, using PBS as the control. Flow cytometry was used to detect the expressions of CD11b, CD11c and CD86 and apoptosis of the stimulated DCs, and IL-12 levels in the cell cultures were detected by ELISA. Mouse spleen cells were co-cultured with the stimulated DCs, and the activation of the spleen cells was assessed by detecting CD69 expression using flow cytometry; TNF-β production in the spleen cells was detected with ELISA. The spleen cells were then co-cultured with LLC cells at the effector: target ratios of 5:1, 10:1 and 20:1 to observe the tumor cell killing. In the animal experiment, C57/BL6 mouse models bearing subcutaneous LLC xenograft received multiple injections with the stimulated DCs, and the tumor growth was observed.@*RESULTS@#The content of HMGB1 in the TCL prepared using GA-treated LLC cells was significantly reduced (P < 0.01). Compared with NH-TCL, LH-TCL showed a stronger ability to reduce apoptosis (P < 0.001) and promote activation and IL- 12 production in the DCs. Compared with those with NH-TCL stimulation, the DCs stimulated with LH-TCL more effectively induced activation of splenic lymphocytes and enhanced their anti-tumor immunity (P < 0.05). In the cell co-cultures, the spleen lymphocytes activated by LH-TCL-stimulated DCs showed significantly enhanced LLC cell killing activity (P < 0.01). In the tumor-bearing mice, injections of LH-TCL-stimulated DCs effectively activated host anti-tumor immunity and inhibited the growth of the tumor xenografts (P < 0.05).@*CONCLUSION@#Stimulation of the DCs with LH-TCL enhances the anti-tumor immune activity of the DCs and improve the efficacy of DCbased immunotherapy for LLC in mice.
Subject(s)
Animals , Humans , Mice , Apoptosis , Dendritic Cells/immunology , Glycyrrhizic Acid/pharmacology , HMGB1 Protein , Lung Neoplasms/immunologyABSTRACT
Objective@#To investigate the feasibility of myeloid and plasmacytoid dendritic cell combined vaccines loaded with heat-treated Lewis lung cancer cell lysates for treatment of lung cancer in mice.@*Methods@#Bone marrow cells were induced by the recombinant mouse fms-like tyrosine kinase receptor 3 ligand (rmFlt3-L) in vitro, myeloid dendritic cells (mDC) and plasmacytoid dendritic cells (pDC) were separated by magnetic beads. The mDC, pDC, and mDC∶pDC=1∶1 were stimulated with heat-treated Lewis lung cancer cell lysates, respectively. The effects of each group on stimulating of lymphocyte proliferation and inducing of T cell to kill tumor cells in vitro were compared. The alternations of the immunophenotypes of CD80, CD86, CD40 and major histocompatibility complex Ⅱ (MHC-Ⅱ) were detected by flow cytometry. The secretion of cytokines including interlukin-12 (IL-12), interlukin-6 (IL-6), and tumor necrosis factor α (TNF-α) were detected by enzyme-linked immunosorbent assay (ELISA).@*Results@#The lymphocyte proliferation in mice stimulated with mDC+ pDC group loaded with heat-treated Lewis lung cancer cell lysates was 10.80±0.66, significantly higher than 8.63±0.65 of mDC group and 7.10±0.46 pDC group under the same culture conditions, respectively (P<0.05). When the ratio of effector cells: target cells (E∶T) was 10∶1, the killing rate of the mDC+ pDC group loaded with heat-treated tumor cell lysate was 31.68%±2.93%, significantly higher than 17.44%±0.97% of mDC group and 10.29%±1.33% of pDC group, respectively (P<0.05). When the ratio of E∶T was 20∶1, the killing rate of the mDC+ pDC group loaded with heat-treated tumor cell lysate was 54.77%±3.28%, significantly higher than 35.25%±1.51% of mDC group and 15.52%±0.73% of pDC group, respectively (P<0.05). When the ratio of E∶T was 40∶1, the killing rate of the mDC+ pDC group loaded with heat-treated tumor cell lysate was 73.01%±0.91%, significantly higher than 51.36%±0.58% of mDC group and 22.65%±1.28% of pDC group, respectively (P<0.05). With the rate of E∶T increased, the killing rate also increased. The mean fluorescence intensities of surface molecules including CD80, CD86, CD40 and MHC-Ⅱ of mDC: pDC=1 group pulsed with heat-treated Lewis lung cancer cell lysates were higher than those of mDC group and pDC group. The IL-6 cytokine concentrations of mDC+ pDC group, mDC group and pDC group loaded with heat-treated Lewis lung cancer cell lysates were (586.67±52.52) pg/ml, (323.33±67.14) pg/ml and (166.67±16.07) pg/ml, respectively. The concentrations of IL-12 in each group were (2 568.75±119.24) pg/ml, (2 156.25±120.55) pg/ml and (672.92±31.46) pg/ml, respectively. The concentrations of TNF-α in each group were (789.33±48.08) pg/ml, (584.89±116.49) pg/ml and (291.56±40.73) pg/ml, respectively. The concentrations of IL-6, IL-12 and TNF-α secreted by mDC+ pDC group were much higher than those of mDC group and pDC group under the same culture conditions (P<0.05).@*Conclusions@#The mDCs and pDCs combined vaccines pulsed with heat-treated Lewis lung cancer cell lysates have synergistic effects on inducing of T lymphocyte proliferation and killing tumor cells in vitro. This synergistic anti-tumor effect is related with up-regulation of co-stimulatory molecules and increased secretion of cytokines.
ABSTRACT
PURPOSE: Activated bone marrow-derived dendritic cells (DCs) express high level of MHC class I and II molecules as well as intercellular adhesion molecule and B7, required for T cell activation. This study was designed to examine whether DCs pulsed with tumor lysates were capable of inducing tumor specific CTLs. METHODS: To generate mature DCs, bone marrow cells of female BALB/c mice were cultured in the presence of GM-CSF and IL-4. Mature DCs were idenfied by surface expression of MHC class II molecules and costimulatory molecules. By FACS analysis, it was found that most DCs highly expressed B7-1, B-7-2 and CD40 as well as MHC class II molecules. BAlB/c were immunized subcutaneously. Cytolytic activity was determined by chromium release assay using splenocytes harvested from immunized mice 7 days after the immunization, Cytolytic activity was measured against CT-26 and RAG tumor cells. In vivo protection experiment was performed. Mice were immunized subcutaneously wity DCs pulsed with CT-26 lysates (1x10(6) per mouse) and were challenged intrahepatically with wild type CT-26 (5x10(4) per mouse) two weeks following immunization. Three weeks after the challenge, animals were euthanized for identification of hepatic tumors. RESULTS: Lysis of CT-26 cells were significantly greater with the splenocytes from the immunized mice. Incidence and mean volume of hepatic cancer in the immunized group were 50% (5/10) and 78+/-22 mm3. These results were significantly different from those from control groups:100% (10/10) and 1014.5+/-667.8 mm3 in media treated group, 90% (9/10) and 855.5+/-270.6 mm3 in mice treated with irradiated CT-26, 100% (10/10) and 994 255 mm3 in the animals treated with DC alone. CONCLUSIONS: DCs pulsed with CT-26 lysates could successfully induce antitumor immunity in the BLAB/c against syngeneic CT-26 carcinoma cells. Pulsing method was so simple that neither genetic engineerings nor cellular fusion were not necessary. Even though the present study did not conduct survival experiments, it was thought that clinical application of DC-based immunotherapy could be expedited by pulsing of tumor lysate into the DCs.