Immunotherapy of hepatocellular carcinoma by melanoma-associated antigen-A3 activated dendritic cells-induced antigen-specific CD8+ cytotoxic T lymphocytes

Abstract

Objective To observe the effect of immunotherapy on hepatocellular carcinoma (HCC) by melanoma-associated antigen-A3 (MAGE-A3) activated dendritic cells (DC)-induced antigen-specific CD8+ cytotoxic T lymphocytes (CTL) and offer help to HCC treatment. Methods After MAGE-A3 activated DC biomarkers, interleukin (IL)-12, and IL-10 in DC were tested. MAGE-A3-DC was used to induce antigen-specific CD8+ CTL. The apoptosis of L02 cells and HepG2 cells was detected after treatment with CD8+ CTL. Interferon (IFN)-γ of CD8+ CTL was detected by enzyme-linked immunospot assay (ELISPOT). Subcutaneous tumor model of mouse HCC was established. The tumor volume of different groups was measured. Tumor tissue was further observed by pathological sections. Results MAGE-A3 protein stimulation significantly increased the levels of Human leukocyte antigen-DR (HLA-DR), DC83, DC86 and DC80 markers on the surface of DC (97.45±2.58 vs. 48.33±1.68, 92.81±2.36 vs. 52.92±1.90, 94.00±3.01 vs. 53.97±2.05, 92.16±1.87 vs. 34.13±1.32; t=35.680, P=0.013; t=29.440, P=0.021; t=24.580, P=0.012; t=56.690, P=0.009). The IL-12 level of MAGE-A3-DC was significantly higher than that of DC [(338.44±18.15) pg/ml vs. (243.23±16.56) pg/ml; t=8.670, P=0.005], but IL-10 level of MAGE-A3-DC was significantly lower than that of DC [(207.21±10.89) pg/ml vs. (327.58±14.36) pg/ml; t=14.930, P=0.009]. The apoptosis of L02 cells treated with MAGE-A3-DC-CD8+ CTL was similar to that after treatment with DC-CD8+ CTL [(9.10±1.40)% vs. (9.71±1.58)%; t=0.650, P=0.120]. The apoptostic rate of HepG2 cells treated with MAGE-A3-DC-CD8+ CTL was significantly higher than that after treatment with DC-CD8+ CTL [(58.84±5.27)% vs. (9.63±1.61)%; t=19.970, P=0.008]. After therapy, tumor sizes V/V0 in MAGE-A3-DC-CD8+ CTL group decreased significantly as compared with those of phosphate buffer (PBS) group and DC-CD8+ CTL group (5.43±1.22 vs. 21.81±2.01 vs. 22.85±2.40; t=22.030, P=0.010; t=20.460, P=0.012). Hematoxylin and eosin (HE) staining showed that nuclear condensation, increased cell gap, vacuoles, and edema were observed in tumor tissues after treatment with MAGE-A3-DC-CD8+ CTL, but pathological changes of tumor tissues were not observed in PBS group and DC-CD8+ CTL group. Conclusion MAGE-A3 protein can stimulate the maturation of DC that induce the production of MAGE-A3 specific CD8+ CTL. MAGE-A3-DC-CD8+ CTL have specific tumor killing ability. Key words: Carcinoma, hepatocellular; Immunotherapy; Melanoma-associated antigen-A3; Dendritic cells; Cytotoxic T lymphocytes