Immunity principles Flashcards
How and when does the Innate Immune System protect from infection? (Main principle only)
It is the first line of defense. Main principle: Uses high-diversity (but low-specificity) molecules to recognize pathogen-associated patterns and protect while the Adaptive branch ramps up.
What are the components of our Innate Immune System that protect from infection?
(1) Barrier defenses (2) Complement (3) Inflammatory defenses PRRs Phagocytes (M, N) Non-phagocytes, e.g. eosino’s/NKs
How quickly can the Innate Immune System respond to infection?
Minutes to hours.
How quickly can the Adaptive Immune System respond to infection?
Depends on the host’s immune status and the particular pathogen. Typically >= 7 days. 7-10d = IgM >=10d = IgG + IgM 2-3mo = IgG only (mb lifelong)
What are the main components of the Adaptive Immune System?
Two branches: (1) Humoral. (2) Cell-Mediated. Humoral: B cells (naive ->plasma + resting memory). CD4+ T cells Antibodies Cell-Mediated: T cells Any nucleated cell has MHC I (to display processed Ag). Cytokines to activate other cells
Which cells have MHC I molecules? What is the purpose of MHC I?
All nucleated cells (not RBCs). Present processed Ag showing cytotoxic immune cells that it’s self (unless infected, then “kill me”). Monitored by CD8+ T cells or NK cells.
Which cells have MHC II molecules? What is the purpose of MHC II?
Only APCs (macrophages, DCs, B cells). Present Ag to CD4+ T cells.
What are the main purposes of antibodies?
Neutralize virus/toxin Activate complement
What is the function of IgA? Where is it found?
Protects @ mucous membranes, saliva, tears. 10-valent.
What is the function of IgM? Where is it found?
1st to be made by the body to fight a new infection. @ blood + lymph. 5mer.
What is the function of IgG? Where is it found?
Long-term protection. Most abundant Ab @ all body fluids.
What is the function of IgE? Where is it found?
Assoc w allergic reactions, mast cell degranulation. @ mucous membranes (including lungs)
How are polysaccharide and protein antigens processed/presented differently by the immune system? How must this be considered in vaccine development?
Protein Ag’s are presented on MHC II to CD4 T cells. Some polysaccharide Ag’s can be recognized + responded to independently of T cells for those ~2yo (but not those <2yo). This response is predominantly IgM and provides no memory response. Vaccines for young children (<2yo) should contain protein components or at least conjugates in order for them to work. Conjugate vaccines help deliver a memory response.
