Inhibition of cell-mediated lympholysis by cloned and uncloned lines of natural killer cells and cytotoxic T lymphocytes with sugars and lectins

This study was designed to further understand the nature of the interaction between natural killer (NK) cells and their susceptible targets. To do this, a panel of sugars and two lectins was tested for the ability to inhibit the lysis of NK-sensitive targets by cloned and uncloned lines of human NK cells. Six of these sugars (beta-gentiobiose, sucrose, alpha-lactose, beta-lactose, N-acetylglucosamine, and N-acetylgalactosamine) and one lectin, wheat germ agglutinin (WGA), proved to be potent inhibitors of the lytic activity of NK cells as well as of cytotoxic T lymphocytes activated in mixed lymphocyte cultures. Both beta-gentiobiose and WGA were shown to inhibit lysis at the level of the killer cell. Finally, the inhibitory effect of WGA could be reversed by addition of its sugar ligand, N-acetylglucosamine, which is itself an inhibitor of lytic function. From these findings it is concluded that these inhibitors probably do not act at the recognition stage of lysis since all of the NK and CTL lines tested, regardless of specificity, were inhibited by the same panel of sugars and lectins. Instead, it appears more likely that these inhibitors block some postrecognition stage of the lytic mechanism. The common inhibition profile by these sugars on NK and CTL activity further suggests that these two cell types may share, at least partially, a common lytic mechanism.