What does human immune function include?

Human immune function is the body's ability to protect itself from harm caused by viruses, bacteria, or toxic substances. This immune function is achieved by regulating the responses of the human immune system, which emphasizes various forms of immune reactions, including cellular and humoral responses. These immune responses can be further divided into physical and biological reactions. Physical reactions primarily involve mechanisms that defend against invasion by foreign substances such as bacteria and viruses. Biological reactions, on the other hand, involve specific cells in the body—such as lymphocytes, monocytes, macrophages, and white blood cells—that respond to changes in the external environment by secreting and expressing various immune factors and receptors. This promotes the initiation and development of immune system responses, thereby enabling effective defense against foreign substances and minimizing damage to the body.