Mucins form a nanoscale material barrier against immune cell attack

ABSTRACT The cancer cell glycocalyx serves as a major line of defense against immune surveillance. However, how specific physical properties of the glycocalyx contribute to immune evasion and how these properties are regulated are not well understood. Here, we uncover how the surface density, glycosylation, and crosslinking of cancer-associated mucins contribute to the nanoscale material thickness of the glycocalyx, and further analyze the effect of the glycocalyx thickness on resistance to effector cell attack. Natural Killer (NK) cell-mediated cytotoxicity exhibits a near perfect inverse correlation with the glycocalyx thickness of target cells regardless of the specific glycan structures present. NK cells expressing a chimeric antigen receptor (CAR) have an enhanced ability to breach the glycocalyx and kill target cells. Equipping the NK cell surface with a mucin-digesting enzyme also improves killing with a performance enhancement that rivals or exceeds CARs in some cases. Together, our results provide new considerations for improving cancer immunotherapies.