What is the difference between innate and adaptive immune systems?

The difference between the innate and adaptive immune systems has to do with how they work. The innate immune system is designed to provide a kind of "shock and awe" protection against bacteria, viruses and other invaders. When cells in the innate immune system "see" an invader, they rush in to destroy it, often by releasing inflammatory chemicals such as histamines and leukotrienes. These invaders display "signs" on their surface called antigens that signal immune system cells to action.

The adaptive immune system provides a more targeted approach. As immature T and B lymphocytes encounter invaders, they develop specific antibodies against them. These "mature" lymphocytes hang out in tissue, ready to quickly spring to action when they encounter the same invader. This creates immunologic memory and prevents reinfection.
Anthony L. Komaroff, MD
Internal Medicine
The innate immune system has its limitations. First, its response is not as nimbly specific as that of the adaptive immune response. Although, as a group, pattern-recognition receptors (PRRs) can recognize many pathogens, the innate immune system mounts a generalized defense effective for some invaders but less effective for others. Second, it retains no memory of the foe it vanquished. And memory, a key feature of the adaptive immune system, is important for fending off invaders the next time they make an appearance.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.