What does the immune system primarily target?

The immune system primarily targets pathogens such as bacteria and viruses because its main function is to identify and eliminate foreign invaders that can cause disease. Pathogens are organisms that can lead to illness, and the immune system has evolved a complex array of cells and mechanisms to recognize these harmful agents and mount an appropriate response to neutralize them. This includes the activation of various immune cells like T cells and B cells, which work together to destroy infected cells and produce antibodies that specifically target the pathogens.

While beneficial bacteria and microbes play important roles in human health, such as aiding in digestion and protecting against harmful pathogens, the immune system does not typically target them as threats. Nutrient absorption in the digestive system is a separate biological process that does not involve the immune system directly. Similarly, while the immune system can target malfunctioning host cells, as seen in autoimmune diseases where the body mistakenly attacks its own cells, the primary function of the immune system is to defend against external pathogens. Therefore, targeting pathogens is a fundamental role of the immune system in maintaining health and defending against disease.