The adaptive immune response is the branch of the immune system that develops a specific, targeted defense against pathogens.
Unlike the innate immune system (the body’s immediate, nonspecific defense), the adaptive immune system recognizes and remembers particular microbes, leading to a stronger and faster response upon future exposure.
Specificity – It targets unique antigens (molecules on pathogens or abnormal cells).
Memory – After an infection or vaccination, memory cells remain, providing long-lasting protection.
Diversity – It can recognize a vast range of possible antigens.
Self vs. Non-self Recognition – It normally distinguishes the body’s own cells from foreign invaders.
Lymphocytes (white blood cells):
B cells → produce antibodies that bind to specific antigens, neutralize pathogens, and mark them for destruction.
T cells:
Helper T cells (CD4⁺) → activate B cells, cytotoxic T cells, and orchestrate immune responses.
Cytotoxic T cells (CD8⁺) → directly kill virus-infected cells or cancer cells.
Antibodies – Proteins secreted by plasma B cells that specifically bind to antigens.
Memory cells – Long-lived B and T cells that enable quicker, stronger responses during reinfection.
Recognition – Antigen-presenting cells (like dendritic cells) present foreign antigens to lymphocytes.
Activation – Lymphocytes (B and T cells) are activated and proliferate (clonal expansion).
Effector phase – Antibodies are secreted, and T cells attack infected or abnormal cells.
Memory phase – After the threat is cleared, memory cells remain for future protection.
The adaptive immune response is antigen-specific.
👉 In short, the adaptive immune response is a highly specific, learned defense system that provides long-term immunity — the basis of how vaccines work.
Would you like me to also compare adaptive vs. innate immunity in a clear table format for quick review?
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