What is adaptive immunity?

Adaptive immunity is the body's response to specific invaders (antigens) such as viruses or bacteria. Your adaptive immune system provides a targeted approach to threats. The foundation of this system exists in cells called T and B lymphocytes. These immune cells learn to recognize certain antigens. Once they identify an invader, they generate specific responses to destroy that invader.

B cells mature into specialized cells with antigen-specific antibodies on their surfaces that lock onto the antigen to annihilate it. T cells release toxins to destroy the invader or call other immune system cells into action. Once T and B cells are activated, they leave behind copies of themselves that are ready to spring into action again if the specific antigen appears. This is known as immunologic memory.

These mature T and B cells enable your immune system to launch an attack against, say, a measles virus so quickly that the virus never has time to infect healthy cells and make you sick. Thus, the adaptive immune system, unlike the innate immune system, protects against reinfection.

The problem with the adaptive immune system is that it can take several days to get up to speed the first time it encounters a new antigen. That's more than enough time for most antigens to replicate and make you sick.
Anthony L. Komaroff, MD
Internal Medicine
Adaptive immunity is the response of antigen-specific lymphocytes to antigens. After the first response of lymphocytes to a pathogen, memory B and T cells remain to fight more effectively against the pathogen if it ever returns.

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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.