Progression of carcinogen‐induced fibrosarcomas is associated with the accumulation of naïve CD4+ T cells via blood vessels and lymphatics

What's new? It is well known that a tumors' microenvironment can impair the anti‐tumor immune response. The culprits are usually assumed to be various suppressor cells and cytokines. In this study, however, the authors found that seemingly innocuous, naïve T cells may also play a significant role—simply by accumulating and possibly out‐competing activated effector cells within the tumor. A better understanding of the signals produced by the tumor microenvironment may allow researchers to alter this T‐cell pool, thus enhancing the immune response.