Comparative analysis of natural killer cell and macrophage recognition of concanavalin A-resistant Chinese hamster ovary cells: role of membrane oligosaccharides.

As was previously shown, a mutation rendering Chinese hamster ovary (CHO) cells concanavalin A (Con A) resistant (Con AR) resulted in enhanced binding and susceptibility to lysis by natural killer (NK) cells. In the present study altered cell surface carbohydrate expression on the Con AR CR-7 cell line was demonstrated. This could be detected by flow cytometry with the use of fluorescein isothiocyanate-conjugated lectins Con A, wheat-germ agglutinin, and peanut agglutinin, and by a radiolabeled monoclonal antibody (49H.8) that recognizes a phenyl-P-galactose determinant. Two other independently selected Con AR CHO lines (BCR-2 and ECR-1) also exhibited increased NK cell reactivity, which suggests that a similar and, likely, a single mutation has altered the phenotype of these cells. Tunicamycin, an inhibitor of N-linked glycosylation, was able to reverse the binding to the CHO lines with the use of conditions that did not affect protein or DNA synthesis. The mutation rendering the CR-7 line Con AR and more sensitive to NK cell lysis and binding resulted in reduced killing and adhesion by activated bone marrow-derived macrophages from DBA/2J and CBA/CaJ mouse strains. Inhibition of macrophage and NK cell lysis by simple monosaccharides was demonstrated; however, macrophage killing was inhibited only by D-mannose, whereas NK cell lysis was reduced by all sugars tested. Neither macrophage nor NK cell adherence to tumor monolayers was affected by any of the monosaccharides. These results suggest that complex N-linked oligosaccharides are important for NK cell and macrophage binding and lysis.