Natural killer cells discriminate between high mannose- and complex-type asparagine-linked oligosaccharides

Abstract

Chinese hamster ovary cell lines with different types of N-linked oligosaccharides were tested as targets for control and lymphokine treated natural killer (NK) cells. The targets tested were parent cells, Lec1 mutants and Lec4 mutants. Due to an apparent defect in GlcNAc transferase V, Lec4 cells produce complex-type N-linked oligosaccharides devoid of GlcNAc β(1–6) linked branches. Lec1 cells form only high mannose-type N-linked oligosaccharides because they lack GlcNAc transferase I activity. Lec1 cells are very sensitive to lysis by β-interferon treated human NK cells, but both parent and Lec4 cells are resistant to NK lysis. The ability to discriminate between parent and Lec1 targets was demonstrated with untreated control effectors as well as those which were pretreated with either β-interferon, γ-interferon or interleukin-2. Both control and lymphokine-boosted NK cells exhibit much greater lytic activity against targets having only high mannose-type N-linked oligosaccharides. Five oligosaccharide structures resembling those found on N-linked glycoproteins were tested for their ability to block NK lysis of Lec1 targets. Only the high mannose-type glycopeptide from 7S soybean glycoprotein was inhibitory in the μmolar range. At the same concentration, none of the complex-type oligosaccharides had any effect on lytic activity. The results suggest that a high mannose-type N-linked oligosaccharides is recognized at some step in NK cell-mediated lysis.