Zusammenfassung der Ressource
Innate Immunity
- Antigens
- Invoke immune responses (B-cell)
- "Antibody generators"
- WBCs
- Innate: macrophages,
respond to all
- Adaptive: B & T cells,
specific response
- Skin barrier
- pH
- Shedding
- [NaCl]
- Mucous Membranes
- lysozyme
(attack cell wall)
- lactoferrin (sequesters Fe)
- Lactoperoxidase (superoxide radicals)
- Antimicrobial
Peptides (AMPs)
- Cationic peptides (highly
conserved, damage bacteria pm)
- 1st class (a-helic, no
cysteine, prod by
macrophages)
- Cathelicidin (LL-37)
- Protect
kidney in UT
w/neutrophils
- Humans protected by
zwitterionic (0 charge)
membranes
- 2nd class: Defensins (disulfide
linked, neutrophils, epithelial)
- Kill phagocytosed bact. by binding to
membrane and forming pores for lysis
- 3rd class: larger,
enriched for specific
am. ac.
- Histatin
- In saliva, anti-fungal (c. albicans)
- Bacteriocins
- Produced by normal flora
- Lethal to related species
- Colicins (E. coli) form pores &
binds to specific recptors
(porins)
- Complement System
- Major activities
- Defense against bacterial infections
- Crosstalk b/w innate
and adaptive immunity
- Disposing waste
- Opsonization
- Decorating microbes with
"opsonins" for recognition
by phagocytic cells
- Stimulates
macrophages for
phagocytosis
- Activation of C proteins
- Enzymatic cleavage
- C#b proteins bind to complex
- C#a proteins diffuse to be
inflammatory mediators (binds to
receptor)
- Functions
- Opsonization (C3b)
- Inflammation (C#a)
- Cell lysis via MAC
- The Three Pathways
- Alternative
- Antibody-independent,
initiated by foreign cell
surfaces
- C3 cleaves to C3 convertase
- C3 convertase cleaves
with C3 to C5 converstase
- C5 goes to be the MAC
- Lectin
- Lectin or
Mannose-Binding
Lecting (MBL) binds
to carbohydrates
- 2 serine protesase
(MASP-1, MASP-2)
- Activates with
C3 and Lectin
- Mannose Binding Proteins
(MBP) on pathogen surfaces
- Enhance phagocytosis
- Classical
- Initiated by forming Ag-Ab
(Antigen-Antibody) complex
- Part of Acquired
& not as fast
- Produces cleavage
products that help in:
- Opsonization
- Chemotaxis
- MAC
- C1 is activated
when bound to
antibody
- Yields C2 & C4
- C4a diffuses
- C2a diffuses
- C4b and C2b become C3
- Complement Proteins
- C3b
- Opsonin
- C#a
- Show immune cells
infection site
- Recruit macrophages
& neutrophils
- C5b
- Form MAC for lysis
- Pathogen
Recognition
- Opsonin-Independent
Mechanism
- Pathogen
recognition, specific
and non
- Mediated by:
- Lectin-carbohyd
- Protein-protein
- Hydrophob
- Pathogen-Associated
Molecular Patterns (PAMPs)
- Detected by
Pattern Recognition
Receptors (PRRs)
- Can trigger
phagocytes
- Toll Like
Recptors (TLRs)
- Signaling recptors
- Recognize/bind
unique PAMPS
- Triggers signal to
initiate host response
- LPS in Gram -
- Peptidoglycan in Gram +
- Binding activates NFkB
transcription factor (Key for
Cytokine gene transcription)
- Cytokine
- Acts as signal molecule
- Recognized by receptors
on immune cell
- Trigger their function
- Intracellular Digestion
(Phagocytosis)
- Autophagy
- Tags internal microbes
for destruction
w/Ubiquitin
- Phagophore encircles
- Fuse with lysosome to degrade