A family of soluble animal lectins, galectins, with β-galactoside-binding activity, is gaining increased attention. One member of this family, galectin-3, has been previously designated by this group as ∈bp, for its IgE-binding activity. On the basis of the saccharide specificity and other biochemical characteristics of ∈bp, it is possible that this lectin could have an important extracellular modulatory role, functioning through recognition of critical cell surface glycoproteins on many cell types. We present evidence here that recombinant human ∈bp activates human neutrophils in a dose-dependent manner as demonstrated by superoxide production. The observed activity is dependent on the lectin property of ∈bp intrinsic to its carboxyl-terminal domain, as it could be inhibited effectively by lactose, a known saccharide ligand of ∈bp. However, the amino-terminal domain is also necessary for the observed activity, as ∈bp-C (the carboxyl-terminal domain fragment) is devoid of neutrophil-activating activity, even though it retains the carbohydrate-binding property. Affinity purification of lysates from cell surface-radioiodinated neutrophils revealed two major protein bands of Mr 115,000 and Mr 180,000 that are recognized by ∈bp and preliminary data suggested that one of these proteins is NCA-160, a human carcinoembryonic Ag-related glycoprotein. This study thus lends further support to our view of an extracellular function for ∈bp and suggests that this protein has an important role in inflammation and host defense through modulating the function of neutrophils.
|Original language||English (US)|
|Number of pages||9|
|Journal||Journal of Immunology|
|State||Published - 1995|
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