Selectins are a type of cell adhesion molecule that play a crucial role in the immune system. They help white blood cells adhere to the walls of blood vessels, allowing them to exit the bloodstream and reach sites of inflammation or injury. There are three main types of selectins: E-selectin, P-selectin, and L-selectin, each with specific functions and locations in the body. These molecules work by binding to specific carbohydrates on the surface of other cells, facilitating the movement of immune cells. This process is essential for the body's response to infections and injuries, ensuring that immune cells can effectively reach and combat pathogens or damaged tissues.