We previously showed that tenascin-XB (TNXB) contributes to tumor suppressor function. The present study aimed to assess the tumor-suppressive mechanism of TNXB by focusing on immune cell infiltration into the tumor microenvironment (TME). We revealed that B16-OVA melanoma cells (MO5)-bearing TNXB-deficient (Tnxb-/-) mice exhibited significant tumor progression and a poor survival rate. Allogeneic mixed lymphocyte reaction showed reduced numbers and increased activation of both CD4+ and CD8+ T cells from Tnxb-/- spleens. Moreover, T cell activation assay further proved that CD4+ and CD8+ T cells from Tnxb-/- mice were more activated than those from WT mice. RT-qPCR analysis showed that expression of T cell activation-related cytokines and chemokines was significantly decreased in tumor tissues from Tnxb-/- mice. Flow cytometry analysis revealed a reduced infiltration level of CD8+ T cells in both naïve spleens and tumor tissues in Tnxb-/- mice. Ultimately, total activation of CD8+ T cells was decreased in tumor tissues in Tnxb-/- mice. In conclusion, we found that although Tnxb-/- CD4+ and CD8+ T cells tend to be activated more than WT CD4+ and CD8+ T cells, CD8+ T cell infiltration and activation level were attenuated in tumor sites of Tnxb-/- mice.
GONG et al. (Sat,) studied this question.