title: An oligosaccharide biosynthetic defect in concanavalin A-resistant Chinese hamster ovary (CHO) cells that enhances NK reactivity in vitro and in vivo.
abstract: We have examined a concanavalin A-resistant (Con AR) Chinese hamster ovary cell (CR-7) that has a defect in the synthesis of asparagine-linked oligosaccharides and consequently an altered expression of membrane carbohydrate. The CR-7 mutant, which has a decreased ability to incorporate mannose into oligolipid and membrane glycoprotein and an increased membrane fucose, was more sensitive to natural killer (NK) cell lysis than the parental wild type (CHO-WT). Splenocytes mediating the lysis of the CR-7 line were asialo GM1+, nonadherent, IFN stimulatable, absent in the bg/bg mutant, and co-fractionated on Percoll density gradients with cells mediating lysis of the YAC-1 murine lymphoma. The increase in NK lysis correlated with enhanced binding of NK cells to the mutant determined by adsorption on tumor monolayers, cold target inhibition, and target binding analysis. A revertant of CR-7 (RCR-7), which showed wild-type levels of NK lysis, was intermediate in its ability to bind or cold target inhibit NK cells. The CR-7, CHO-WT, and RCR-7 lines were equally sensitive to hypotonic lysis and cytotoxicity by human lymphokine-activated killer (LAK) cells suggesting that the mutation did not nonspecifically alter membrane fragility. The NK-sensitive CR-7 line was less tumorigenic after subcutaneous injection in nude mice when compared with the parental CHO-WT or RCR-7 lines. This decreased tumorigenicity could be reversed by the i.v. injection of antiserum directed at the NK cell determinant asialo GM1. In conclusion, a ConAR tumor cell with a demonstrable oligosaccharide biosynthetic defect, exhibited enhanced NK lytic sensitivity and was poorly tumorigenic in vivo, a feature which may also be a consequence of its altered NK reactivity.
mesh_terms: D000042:Absorption; D000818:Animals; D001667:Binding, Competitive; D002450:Cell Communication; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003208:Concanavalin A / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D003602:Cytotoxicity, Immunologic; D007694:Killer Cells, Natural / Q000276:immunology* / Q000502:physiology; D008223:Lymphoma / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009844:Oligosaccharides / Q000096:biosynthesis*
chemical_list: D009844:Oligosaccharides; D003208:Concanavalin A