DIFFERENTIAL BINDING OF LECTINS IL-2 AND CSL TO CANDIDA-ALBICANS AND CANCER-CELLS

The demonstration that interleukin 2 (IL-2) is a lectin specific for o ligomannosides allows to understand a new function for this cytokine: as a bifunctional molecule when bound to its receptor beta, IL-2 assoc iates the latter which the CD3/TCR complex, interacting with oligosacc harides of CD3 through its carbohydrate-recognition domain (Zanetta et al., 1996, Biochem. J., 318, 49-53). This induces the tyrosine phosph orylation of the IL-2R beta by p56(lck), the first step of the IL-2-de pendent signaling. Since this specific association is disrupted in vit ro by oligomannosides with five and six mannose residues, we made the hypothesis that pathogenic cells or microorganisms could bind IL-2, co nsequently disturbing the IL-2-dependent response. This study shows th at the pathogenic yeast Candida albicans (in contrast with nonpathogen ic yeasts) binds high amounts of IL-2 as did cancer cells. In contrast with cancer cells, yeasts do not bind the Man(6)GlcNAc(2)-specific le ctin CSL, an endogenous ''amplifier of activation signals''.