Collaboration between Innate and Adaptive Immunity

Collaboration between Innate and Adaptive Immunity

Innate and Adaptive immunity do not operate in total indepen-dence of each other. They cooperate in important ways to produce more effective immunity. For example, the encounter between mac-rophages and microbes can generate antigen presenting cells that stimu-late and direct adaptive immune responses. This facilitates the partici-pation of the adaptive immune system in the elimination of the patho-gen. Macrophages also secrete immunoregulatory hormone-like mol-ecules, called cytokines. The cytokines and other signals generated by innate immunity play important roles in triggering lymphocyte responses.

The adaptive immune system produces signals and components that stimulate and increase the effectiveness of innate responses. There is increase in the ability of macrophages to kill the microbes they have ingested. The production of antibodies against an invading pathogen also has important effects on the recruitment of the complement system to the defense of the host. By binding to the pathogen, antibodies mark it as a target for attack by complement, and the complex of antibody and pathogen is also a potent activator of this attack. Thus, these two systems, nonspecific and specific immunity, form an interactive and mutually supportive network that erects an effective and formidable barrier to infection.