Differential Expression of CD49a and CD49b Determines Localization and Function of Tumor-Infiltrating CD8 T Cells.

CD8 T-cell infiltration and effector activity in tumors are correlated with better overall survival of patients, suggesting that the ability of T cells to enter and remain in contact with tumor cells supports tumor control. CD8 T cells express the collagen-binding integrins CD49a and CD49b, but little is known about their function or how their expression is regulated in the tumor microenvironment (TME). Here, we found that tumor-infiltrating CD8 T cells initially expressed CD49b, gained CD49a, and then lost CD49b over the course of tumor outgrowth.