J. Biol. Chem., Vol. 262, Issue 16, 7575-7579, 06, 1987
The role of asparagine-linked carbohydrate in natural killer cell- mediated cytolysis
PB Ahrens and H Ankel
Chinese hamster ovary cell lines with specific lesions in the formation of
glycoconjugates were tested for their sensitivity to lysis by
interferon-boosted human natural killer cells. We report here that the type
of asparagine-linked carbohydrate present on target cell glycoproteins
determines their susceptibility to natural killer lysis. The targets tested
were Chinese hamster ovary parent cells and Lec1, Lec2, and Lec8 mutants.
Lec8 and Lec2 cells show an overall reduction of galactose and/or sialic
acid in their glycoconjugates due to defects in the translocation of
UDP-galactose and CMP-sialic acid, respectively. Due to a specific block in
N-linked carbohydrate processing, Lec1 cells produce only high mannose-type
oligosaccharides, but their glycolipids are identical to those of the
parent. Both Lec2 and Lec8 mutants are more sensitive to natural killer
lysis than the parent cells. This is consistent with their extensive
reduction in cell surface sialic acid. Furthermore, Lec1 mutants are more
susceptible to natural killer lysis than the parent cells. To confirm that
the increased natural killer sensitivity of Lec1 cells was due to the
modification of N-linked carbohydrate, parent cells were treated with
swainsonine, a specific inhibitor of N-linked oligosaccharide processing.
Swainsonine-treated parent cells are nearly as sensitive to natural killer
lysis as the Lec1 mutants.