Background: The antigen HCA587 (also known as MAGE-C2), which is considered a cancer-testis
antigen, exhibits upregulated expression in a wide range of malignant tumors with unique immunological properties,
and may thus serve as a promising target for tumor immunotherapy.
Objective: The study aimed to explore the antitumor effect of the HCA587 protein vaccine and the response of
humoral and cell-mediated immunity.
Methods: The HCA587 protein vaccine was formulated with adjuvants CpG and ISCOM. B16 melanoma cells
were subcutaneously inoculated to C57BL/6 mice, followed by treatment with HCA587 protein vaccine subcutaneously.
Mouse survival was monitored daily, and tumor volume was measured every 2 to 3 days. The tumor
sizes, survival time and immune cells in tumor tissues were detected. And the vital immune cell subset and
effector molecules were explored.
Results: After treatment with HCA587 protein vaccine, the vaccination elicited significant immune responses,
which delayed tumor growth and improved animal survival. The vaccination increased the proportion of CD4+ T
cells expressing IFN-γ and granzyme B in tumor tissues. The depletion of CD4+T cells resulted in an almost
complete abrogation of the antitumor effect of the vaccination, suggesting that the antitumor efficacy was mediated
by CD4+ T cells. In addition, knockout of IFN-γ resulted in a decrease in granzyme B levels, which were
secreted by CD4+ T cells, and the antitumor effect was also significantly attenuated.
Conclusion: The HCA587 protein vaccine may increase the levels of granzyme B expressed by CD4+ T cells,
and this increase is dependent on IFN-γ, and the vaccine resulted in a specific tumor immune response and subsequent
eradication of the tumor.