Adaptive Immunity Notes

Adaptive immunity is acquired only after an immunizing event, such as an infection.
B and T lymphocytes undergo a selective process, preparing them to react to one specific antigen or immunogen.
Immunocompetence: The body's ability to react with countless foreign substances.

Innate, nonspecific defenses:
- First line of defense:
- Surface protection composed of anatomical and physiological barriers.
- Keeps microbes from penetrating sterile body compartments.
- Includes physical barriers, microbiota, and chemical barriers.
- Second line of defense:
- Cellular and chemical system that comes into play if infectious agents bypass surface defenses.
- Includes phagocytosis, inflammation, fever, and antimicrobial products.
Acquired, specific defenses:
- Third line of defense:
- Specific host defenses developed uniquely for each microbe through specialized white blood cells.
- Involves B cells, T cells, gamma-delta T cells, and natural killer T cells.

Antigens: Molecules seen and identified by the immune system.
Immunogens: Antigens that provoke an immune response.
Protein or polysaccharide molecules on or inside cells and viruses.
Any exposed or released protein or polysaccharide is potentially an antigen, even on our own cells.
Our own antigens usually do not evoke a response from our own immune system.

Specificity: Antibodies produced against one virus (e.g., chickenpox) will not function against a different virus (e.g., measles).
Memory: Lymphocytes are programmed to