Evidence that specific oligosaccharides block early events necessary for the expression of antigen-specific proliferation by human lymphocytes.

We have previously shown that monosaccharides and disaccharides will block the expression of spontneous monocyte-mediated cytotoxicity. Our data were consistent with the hypothesis that human mononuclear cells express lectin-like receptors that are capable of binding to a variety sugar moieties found on target cell membranes. In this communication, we will present evidence that monosaccharides and disaccharides are also capable of blocking the expression of T cell reactivity as measured by an in vitro antigen-specific proliferative assay. The majority of sugars that blocked monocyte-mediated cytotoxicity had no effect on antigen-specific proliferation. Those sugars that did suppress antigen-induced proliferation had no effect on PHA-induced proliferation. Furthermore, some of these sugars only inhibited if they were added at the initiation of the assay; they failed to inhibit if added 24 hr after the initiation of the assay. Antigen-pulsing experiments suggested that these sugars did not block antigen uptake by human monocytes. These data suggest that a variety of cellular interactions may be mediated by receptors with specificity for simple sugars. The ability to block these naturally occurring lectins specifically both in vitro and in vivo may prove to be a powerful tool for dissecting out various forms of cellular recognition and collaboration.