Modulation of interleukin-1 induced thymocyte proliferation by D-mannose

We examined the effect of various carbohydrates on the proliferative response of murine thymocytes to cytokines. The monosaccharide, D-mannose (4-10 mM), significantly inhibited thymocyte proliferation induced by recombinant interleukin-1 (rIL-1). Mannose also inhibited the proliferation response to native, human IL-1. Inhibition was specific for D-mannose and methyl-alpha-D-mannopyranoside. Other carbohydrates, including L-mannose and D-glucose did not inhibit thymocyte growth. Thymocyte proliferation induced by either IL-2 or pokeweed mitogen was also inhibited by mannose. Mannose was effective in inhibiting T-cell proliferation even when added 48 hours after the start of the experiment. Mannose did not appear to be toxic to the thymocytes as judged by trypan blue exclusion. These data are consistent with the hypothesis that specific carbohydrates may alter immune function. Manipulation of immune function via blocking cytokine activity may be useful in certain pathological conditions.