LY-49A, A RECEPTOR FOR H-2D(D), HAS A FUNCTIONAL CARBOHYDRATE-RECOGNITION DOMAIN

Ly-49A(+) murine natural killer (NK) cells cannot lyse target cells th at express H-2D(d). We demonstrate a functional requirement for carboh ydrate recognition by Ly-49A. Treatment of H-2D(d+) target cells with tunicamycin prevents their binding to Ly-49A(+) cells and renders them susceptible to lysis by Ly-49A(+) NK cells. Fucoidan, a sulfated poly saccharide, binds to Ly-49A in a calcium-dependent manner, and this bi nding is inhibited by monosaccharides, particularly sulfated hexoses. The inactivation of Ly-49A(+) NK cells by H-2D(d+) target cells is rev ersed in the presence of glucose 6-SO4. These results indicate that Ly -49A has a functional carbohydrate recognition domain and that target expression of carbohydrates alters their susceptibility to natural kil ling.