How are lectins used in blood grouping?

Lectins are proteins that can specifically bind to carbohydrates and are used in blood grouping to identify blood types. They agglutinate red blood cells by binding to specific sugar molecules on the surface of the cells, allowing for differentiation between various blood groups such as A, B, AB, and O. This property is exploited in laboratory tests to determine an individual's blood type, which is crucial for safe blood transfusions and organ transplants. By mixing a blood sample with specific lectins, the resulting agglutination pattern reveals the blood group.