The main function of antibodies in the immune response is to identify and neutralize foreign invaders, such as bacteria and viruses. These proteins are produced by B-cells and specifically target antigens, which are molecules on the surface of pathogens. Once bound to the antigens, antibodies can block pathogen entry into cells, mark them for destruction by other immune cells, or activate the complement system. This action is critical for the body's defense against infections, ensuring the immune system effectively recognizes and responds to diverse threats.