L: 20 Immunity to microbes Flashcards
what is collateral damage
tissue injury and disease caused by the hosts response to microbe rather than microbe itself
Latent or persistent infections
Immune response control but does not eliminate microbe and microbe survives without propagating infections
What are important causes of susceptibility in innate and adaptive immunity
Inherited and acquired immunity
What pathways can lipoplysaccharide (LPS) activate?
Alternative and classical
What pathway do mannan-binding proteins (MBP) activate
Lectin
Acute phase proteins bind bacterial coat and activate _________?
Complement
What binds to receptors on resident mast cells and activates them?
C3a and C5a
Mast cell degranulation releases large amounts of what to enhance blood flow?
Histamines and bradykinin
Histamines acting through what receptors cause arterial vasodilation, venous constriction in some vascular beds and increased permeability?
H1 and H2
What is the first cell to release cytokines and chemokines
Mast cells
What adheres to the vein walls after activation via PRRs
Neutrophils
What are some potent Neutrophil Chemoattractants?
Complement fragments C5a and C3a
Chemokines IL-8/CXCL8
Immature DCs engulf and internalize bacteria (Ags) via?
Pattern recognition receptors (PRRs) (e.g. Toll-Like receptors)
What cells migrate to local LNs via the lymphatics?
Activated mature DCs
After DCs enter the LN they move directly to ?
T cell zone
What leads to the swelling and hyperemia leading to swollen painful/tender LNs
Lymphocytes become trapped, activated, and proliferate in local inflamed LN
The homing of lymphocytes to peripheral LNs is initiated by an adhesive interaction between?
Expressed L-selectin and PNAd displayed on HEV and LNs
What calls are recruited and activated by DCs in lymph node
Naïve Th Cells
Naïve T cells become differentiated towards what three cells according to DC signals?
Th1, Th2, Th17
What cells migrate toward the germinal centers and interact with Ag-activated B cells promoting affinity maturation and Ig class switching
Th cells
Initially _____ class Ab is produced, followed by clonal expansion and ______ to other classes, e.g. IgG or IgA for mucosal pathogens by the engagement of CD40-CD40L
IgM
Switching
IgM is a very potent _____ activator
Complement
After formation of multiple ______ bacteria are lysed by complement
MACs
In the resolution of an infection bacteria debris is removed by what?
Phagocytes or by antibody as soluble immune complexes
What happens to most effector lymphocytes upon elimination of pathogens
Die via apoptosis
Extracellular bacteria are capable of replicating outside of the host cells where?
Blood, Connective tissue< epithelial surfaces, and GI tract
Endotoxins
Components of bacterial cell walls
Exotoxin
Secreted by the bacteria
What are the principle mechanisms of innate immunity to extracellular bacteria?
Complement activation
Phagocytosis
inflammation
Classical pathway cofactors
DAF, CR12, C4BP
Alternative pathway cofactor
DAF, Factor H, CR1
The major mechanism used by bacteria to evade humoral immunity?
Variation of surface Ags
Major Protective Response against extracellular bacteria
Humoral Immunity
The 3 effector mechanisms of Abs include?
- Toxin neutralization
- Opsonization and phagocytosis
- complement activation by classical pathway
Antibodies responses against extracellular bacteria are directed against?
Cell walls Ags
Macrophages release a diverse range of products implicated in?
Sepsis
Global suppressor of macrophage function
IL-10
