Heavy glycocalyx Sia also induces immunologic shielding from anti-tumor immune cells through the activation of repressive Sia-binding Siglecs on immune-cell surfaces (for example, NK-surface Siglec 7-, 9-, or NKG2D-mediated repression of NK cells by engagement with heavy Sia on tumor glycocalyx) (56, 57). The gene discussed is KLRK1; the disease is neoplasm.