Chapters 5 Flashcards
Innate Immunity
- Nonspecific
- Defenses against infection that are ready for immediate activation prior ro attack by a pathogen
- Rapid
- Includes physical, chemical, & cellular barriers
- Activation of Phagocytes
- Inflammation
- Works with adaptive
- Antibody Independent
Adaptive Immunity
- Acquired
- Induced by exposure to microbes & counters infection with a SPECIFIC response with B & T cells
- Memory
- Anitbody Dependent
PRRs can detect what?
- Aging cells
- Dead cells
- Damaged cells
Pathogen-Associated Molecular Patterns
- Sugar, proteins, lipids, nucleic acids, or a combination
- PAMP binding immoblizes infectious organism
- May lead tophagocytosis
- PRR engagement leads to host activation
Endotoxin
LPS on gram-negative bacteria
Peptidoglycan
Recognized by NOD proteins
What receptors recognize Peptidoglycan & LPS?
TLR 2 & TLR 4
TLRs
Toll-Like Receptors
- Mediate recognition of diverse pathogens
- Cytokine activation
- Promote Inflammation
- Recruit WBCs
- Scavenger Receptors
- Opsonins
Opsonins
Any molecule that enhances phagocytosis by marking an antigen for an immune response
Scavenger Receptors
- Involved in binding modified low-density lipoproteins, some polysaccharides, and some nucleic acids
- Internalization of bacteria & phagocytosis of host cells
MICA & MICB
Stress signals on cancer cells
Soluble Defense Mechanisms
- Protection from viral infection
- Lytic destruction of microbes
- Increasing susceptibilty of microbes to ingestion by phagocytes
Type I Interferons (IFNs)
- Soluble means of self defense
- IFN-alpha produced by dendritic cells
- IFN-beta produced by non-leukocytes, such as fibroblasts
- Produced in response to viral infections
- induce both antiviral & apoptotic pathways
Microcidal Molecules
- Cysteine-Rich Peptides = defensins
- Form channels in cell membranes of bacteria
Neutrophils are defensin-rich
The Complement System
A group of serum proteins circulating in inactive form
Outcomes once the Complement System is activated
- Target cell membrane lysis
- Inflammation
- Chemotaxis
- Opsonization to enhance phagocytosis
- Clear immune complexes from circulation
- Secretion of immunoregulatory molecules
Complement Activation
- Alternative Pathway (Innate Immunity)
- Mannan-Binding Lectin (MBL) Pathway (Innate Immunity)
- Classical Pathway (Adaptive Immunity)
The Terminal or Lytic Pathway
- Entered from alternative, MBL, or classical pathway
- Attachement of C5b to bacterial membranes initiates membrane attack complex (MAC)
- MAC = cell lysis
- Unregulated flow of electrolytes
Mannan-Binding Lectin (MBL) Pathway
- Lectins are proteins that bind to specific carbohydrates
- Activated by MBL binding to mannose-containing residues of glycoproteins on certain microbes
- Can interact with MBL-activated serine protease (MASP)
Anaphylotoxins
- Attract & activate different types of leukocytes
- Small fragments
- C5a > C3a >= C4a
Cytokines
- Secreted by WBCs & other cells
- Involved in innate, adaptive, & inflammation
- Antigen-nonspecific
Chemokines
- Subgroup of cytokines
- Involved in chemotaxis of WBCs
Interleukin-1 (IL-1)
Acts on Vascular Endothelium
Interleukin-6 (IL-6)
Acts on Liver
Interleukin-8 (IL-8) [Chemokine]
Acts on Vascular Endothelium
Interleukin-12 (IL-12)
Acts on NK Cells
Tumor Necrosis Factor-alpha (TNF-alpha)
Acts on Vascular Endothelium
Phagocytosis
Engulfment & degradation of molecules
Destruction of Ingested Microbes by
- Lysosomal hydrolases
- Toxic Oxygen Species
- Nitrous Oxide
- Low pH
Secretion of IL-1 & IL-6
Elevate temperature
Secretion of TNF-alpha
Increase vascular permeability
Secretion of IL-8 & IL-12
Attract & activate WBCs (Neutrophils & NK Cells)
NK Cells Responses
- Binding KAR to MICA & MICB generates a kill signal
- KIR assesses MHC-I on target
Early Components of Inflammation include:
- Increased vascular permeability
- Recruitment of neutrophils & other lwukocytes fromthe blood to the site of damage/infection
Cardinal Signs of Inflammation
- Pain
- Heat
- Redness
- Swelling
- Loss of Function
Cell Types of the Innate Immunity
- Neutrophils
- Macrophages
- Dendritic Cells
- NK Cells
Neutrophils
- Phagocytosis
- Reactive oxygen & nitrogen species
- Antimicrobial peptides
Macrophages
- Phagocytosis
- Inflammatoy mediators
- Antigen Presentation
- Reactive oxygen & nitrogen species
- Cytokines
- Complement proteins
Dendritic Cells
- Antigen presentation
- Costimulatory signals
- Reactive oxygen species
- Interferon
- Cytokines
NK Cells
- Lysis of viral-infected cells
- Interferon
- Macrophage activation
