During the immune response, certain types of white blood cells react to __________________________

The immune response is primarily activated when white blood cells encounter antigens, which are specific molecules or markers found on pathogens, such as bacteria, viruses, or other foreign substances. These antigens serve as identifiers that signal the presence of potentially harmful invaders. When white blood cells detect these antigens, they trigger an immune response aimed at neutralizing or eliminating the threat.

White blood cells, such as lymphocytes, are crucial in recognizing these antigens through specialized receptors. This recognition leads to the activation of various immune mechanisms, including the production of antibodies, secretion of signaling molecules, and the mobilization of additional immune cells to the site of infection. Understanding this connection between antigens and the immune response is essential for comprehending how the body protects itself against diseases and infections. Other options like enzymes, hormones, or general pathogens do not specifically describe the targeted interaction that initiates the immune response the way that antigens do.