Introduction to the immune system adaptive immunity

Active immunity is the type of immunity developed when a person’s own immune system produces antibodies and memory cells in response to an infection or vaccination. It provides long-term protection because the immune system “remembers” the pathogen and can respond quickly if exposed again.

1.  Introduction to the Immune System: Adaptive Immunity

2.  What Is Adaptive Immunity? Adaptive (also called acquired or specific) immunity is achieved through experience, either recovery from disease or medical intervention. It is characterized by the ability of lymphocytes to recognize and respond to specific antigens, providing enhanced protection with repeated exposure.

3. Key Phases and Features 1.Phases of Adaptive Immunity : Recognition of antigen Activation of lymphocytes Effector phase (elimination of antigen) Memory phase (stronger secondary response) 2.Features: Specificity Diversity Memory Self/non-self recognition

4. Types of Adaptive Immunity 1.Humoral Immunity : Mediated by B lymphocytes Production of antibodies Targets extracellular microorganisms, like bacteria and fungi 2.Cell-Mediated Immunity: Mediated by T lymphocytes Direct destruction of infected or abnormal cells Targets intracellular pathogens and tumor cells

5. Role of Lymphocytes B Lymphocytes : Protect against extracellular bacteria, extracellular stages of viruses and some fungi T Lymphocytes : Protect against intracellular microorganisms, viruses, cancers, and rejection of transplanted tissues

6.   Diagram - Immune Response Pathways Interaction occurs between helper T cells and B cells. Plasma cells secrete antibodies (humoral immunity), which remove antigens. T cells release cytokines, induce apoptosis of infected cells (cell-mediated immunity).

7. Adaptive Immunity Can Be Active or Passive Humoral and cell-mediated adaptive immunity can be active (body generates own immune response after exposure) or passive (receives antibodies from another source). Active immunity, which develops after antigen exposure, usually lasts for years.