Immunity overview Flashcards
Contrast passive and active immunity
Passive
- receiving preformed Ab (e.g. breastfeeding)
- rapid protection
- short duration (Ab half life= 3 weeks)
Active
- exposure to a foreign antigen (e.g. flu shot)
- slow protection
- long duration -> memory lymphocytes
Define immunogen
A molecule that induces an immune response
Define antigen
A molecule that binds to (is recognized by) adaptive immune mediators aka lymphocytes
Define tolerogen
A molecule that induces immune unresponsiveness to subsequent doses of that molecule (STILL recognized by immune system, just ignored)
Describe characteristics of a very immunogenic molecule
Large and complex, intermediate dose, administered SubQ, adjuvant (bacteria), and effective interaction with MHC complex
What is the difference in specificity between innate and adaptive immunity?
Innate system uses pattern-recognition receptors (TLRs, complement proteins) to recognize PAMPs *limited diversity
Adaptive system uses antien receptors (TCRs recognize peptides, BCRs recognize large complexes of carbs/fats/protein/etc)
Which immune response is most effective long term?
Adaptive immunity (memory T and B cells)
What are the key immunologic decision points?
- Self or foreign?
- Nature of invading antigen/microbe (intracellular/extracellular?)
- Timing of exposure (primary or secondary immune response?)
Contrast live attenuated and inactivated vaccines
Live attenuated
- Modified to decrease pathogenicity (limited growth after injection) *may revert to virulent form
- Induces cellular response (T cells)
- Strong, life-long immunity
Inactivated
- Heat or chemically inactivated pathogen (retains epitope on surface) *stable and safer than live
- Induces humoral response (B cells)
- Weaker immunity- requires booster vaccine
What are generative and peripheral immune organs?
Generative= bone marrow and thymus
Peripheral= lymph nodes, spleen, GALT, tonsils, etc
What are the main components of innate immunity?
Epithelial barriers, phagocytic leukocytes (macrophages, neutrophils), DCs, NK cells, complement
**always “on” so get immediate response
How is the innate immune system activated?
Pattern recognition receptors (e.g. TLRs) recognize PAMPs on bacteria, virus, fungal, or parasite pathogens and activate proinflammatory/anti-viral signaling pathways
**NO MEMORY
How is the adaptive immune system activated?
- Antigen (specifically the epitope region) binds to Ab or T cell receptor
**TCRs only recognize peptide fragments in MHC I/II - MHC I complex -> activates CD8/cytotoxic T cells
MHC II complex -> activates CD4/helper T cells - CD8 T cells KILL
- CD4 T cells HELP
- Release cytokines
- CD40L on T cell binds CD40 and activates cells of innate immunity (macrophage/DC) or naive B cells
Which adaptive immune response deals with intracellular pathogens? Extracellular?
T cells respond to intracellular pathogens (cytoplasmic on MHC I, vesicular/phagocytosed on MHC II)
B cells respond to extracellular pathogens *“Immune surveillance” with circulating Abs
What are the antibody isotopes?
IgD (only on naive B cells), IgM (T cell independent), IgE, IgG, and IgA
What markers are used to differentiate between different types of T cells?
CD4+ for helper T cells, CD8+ for cytotoxic T cells, CD4+/CD25+ for regulatory T cells
What markers are used to identify B cells?
CD19/CD21 and FcR
What markers are used to identify NK cells?
FcRgamma
