OBJECTIVETo understand the influence of co-expression of CD80, CD86 and CD137L genes on tumor immunogenicity in hepatocellular carcinoma H22-BAL B/c mouse models.

METHODSThe mice were randomly divided into five groups, named A, B, C, D and E, and control groups A and B, 20 mice in each group. Hepatocellular carcinoma H22-BAL B/c mouse model was established by subcutaneous injection of cells H22-Wt, H22-neo, H22-CD80/CD86+, H22-CD137L+ and H22-CD80/CD86/CD137L+, respectively. The rate and incubation period of tumor development, survival rate, and the tumor growth in vivo were observed and recorded. The effects of gene transduction on immunogenicity of the tumor and antitumor immunity of the animals were assessed by re-innoculation of wild type H22 cells.

RESULTSThe rate of tumor development in group E was only 50%, much lower than that in other four groups (P < 0. 01). The tumor growth in group C was reduced with complete tumor regression in two hosts (20%, 2/10). In group E, there was more pronounced reduction of tumor size. The maximal tumor sizes were remarkably smaller than those of group C, and there was complete tumor regression in three mice (60%, 3/5). No tumor regression was found in the other three groups. Survival rates of group C and E were significantly higher than that of animals in groups A, B and D (P < 0. 01), but no significant difference was seen between group C and E. The results of re-inoculation test showed that tumor formation rate was 40% (4/10) in group C, 100% (8/8) in group D, and 0 (0/5) in group E. There were significant differences between groups C and E and control group, between group E and C, but not between C and D. After the third time of re-inoculation with H22-Wt cells at the 56th day, tumor occurred in 6/6 mice (100%) of group C, but 0 (0/5) in group E. The difference was very significant. Five animals without tumor formation after the first inoculation in group E, were re-inoculated with H22-Wt cells on the 21st day and the third re-inoculation on the 56th day, no tumor was found (0/5).

CONCLUSIONBoth co-expression and solo-expression of CD80+ CD86 and CD137L genes reduce the tumorigenicity of wild type H22 cells, but co-expression of CD80, CD86 and CD137L genes can more significantly improve the immunogenicity of H22-CD80/CD86/CD137L+ cells.