Which immune system proteins recognize and inactivate invaders?

Antigens are substances that provoke an immune response, typically found on the surface of pathogens such as bacteria and viruses. They are not proteins that recognize invaders; rather, they are the targets that antibodies bind to in order to initiate an immune response.

Cytokines are signaling proteins released by cells that mediate and regulate immunity, inflammation, and hematopoiesis. While they play a vital role in the immune response, they do not directly recognize or inactivate invaders; instead, they help coordinate the activities of various immune cells.

Hormones are regulatory substances produced by glands that travel through the bloodstream to target organs, influencing various physiological processes. They do not play a role in recognizing or inactivating invaders and are not involved in the immune response mechanism.