The monoclonal antibody 2A11 recognizes mouse β-glucan receptor, also known as dectin-1. Dectin-1 is a small type II transmembrane receptor containing one lectin-like carbohydrate recognitiondomain. This domain recognizes β1,3- and/or β1,6-linked glucans, intact yeast and animmunoreceptor tyrosine-based activation motif (ITAM) in the cytoplasmic tail. β-Glucan is one of themost abundant polysaccharides in fungal pathogens. By recognizing β-glucan, dectin-1 has afundamental function in antifungal immunity. Dectin-1 is a signaling non–Toll-like pattern-recognitionreceptor required for the induction of protective immune responses. Dectin-1 is responsible for the β-glucan-dependent, nonopsonic recognition of zymosan by primary macrophages. Zymosan is a yeastderived particle composed principally of polysaccharides, of which β-glucan and mannan are themajor constituents. In vivo administration of zymosan, or purified soluble β-glucans, has a number ofdesirable effects on immune function, including the ability to confer resistance to tumors and variousinfections.The receptor is highly expressed on macrophages and neutrophils and to a lesser extent on dendriticcells and a subpopulation of T cells. Dectin-1 participates with the complement receptor CR3 in ahost proinflammatory cytokine response to a fungal pathogen. The monoclonal antibody 2A11recognizes an extracellular epitope on dectin-1.