Concanavalin A is a lectin protein (MW 104kDa), homotetramer 26 kDa; originally extracted from the jack-bean, Canavalia ensiformis. It binds specifically to certain structures found in various sugars α-mannosyl and α-glucosyl residues in glycoproteins. It was the first lectin to be available on a commercial basis and is widely used in biology and biochemistry to characterize glycoproteins and other sugar-containing entities. It is also used to purify macromolecules in lectin affinity chromatography. Concanavalin A interacts with diverse receptors containing mannose carbohydrates (serum and membrane glycoproteins). ConA agglutinate strongly erythrocytes without being blood group specific. Normal cell reagglutinated after trypsinisation. ConA is noy only a lymphocyte mitogen and reacts with many bacteria, like E. coli Dictyostelium discoideum et B. substilis, but also widely believed to be involved in the interaction between alpha-mannosyl oligosaccharides on the surface of the HIV virus and the human T cell lymphocyte.