Body's Defenses Against Infection Flashcards
Inflammatory Cytokines Actions and Result
- Fat, Muscle
IL-1/IL-6/TNF-alpha causes protein and energy to mobilize to generate more body heat
- Decreases bacterial/viral replication
- Increased antigen processing
- Facilitates adaptive immune response
Sepsis Process
- Bacteria enters systemic blood (Bacteremia)
- Liver Macrophages (Kupffer Cells) are activated by LPS
- Liver Macrophages start to secrete pro-inflammatory cytokines into bloodstream
- Causes widespread coagulation and organ failure (Septic Shock)
Type-I Interferons vs Type-II Interferons
Type-II Interferons are secreted by effector lymphocytes
Type-I Interferons are secreted by virally infected human cells
What are the 4 types of Body Defenses against Infection
- Physical Barriers to prevent infection
- Innate Immune mechanisms of defense
- Adaptive Immune responses
- Immunological memory that lessen the impact of subsequent encounters of same pathogens
Condition which is the main cause of Septic Shock
Disseminated Intravascular Coagulation (DIC)
- Basically widespread intravascular coagulation
C-Reactive Protein function
Acute-Phase Protein
- Binds phosphorylcholine on bacteria surfaces
- Acts as an opsonin (tags the bacteria) and as a complement activator
Complement Pathway
- Lectin Pathway vs other pathways
- MBL binds foreign surface
- MASP1 and MASP2 binds MBL
- Generates C1-like complex
- C1 cleaves C4 just like in Classical/Alternative Pathway pathway
What are the different kinds of Epithelium as a barrier?
Mechanical
- Tight junctions
Chemical
- Enzymes and pH modulations
Microbiological
- Bacterial Commensalism, where bacteria in body competes with foreign bacteria for nutrients
Gamma:Delta T-Cells Function
Subpopulation of T-Cells
- Has a nonconventional surface phenotype
More for rapid response to infection (Does not have gene switching so can have a faster response)
γ:δ T-Cells secrete cytokines and develops cytotoxic function
Function of IL-12
Local Effects
- Activates NK Cells
- Induces differentiation of CD4 T Cells into T-Helper 1 Cells
Intracellular Host Defenses
- Cytoplasmic
- Cytotoxic T-Cells
- NK Cells
Function of IL-6
Local Effects
- Lymphocyte activation
- Increased Antibody production
Systemic Effects
- Fever
- Induces acute-phase protein production by hepatocytes
Local vs Systemic Infection
Local Infection
- Macrophages in tissue are activated and release TNF-alpha
- Release of plasma proteins
- Increased Phagocytosis
- Increased Platelet adhesion to blood vessel wall
–> Infection if contained and antigens are drained/carried to lymph node
Systemic Infection
- Macrophages in liver are activated and release TNF-alpha
- Fluids leak into tissue (systemic edema), less blood volume in central compartment causing collapse of vessels
- Disseminated Intravascular Coagulation (DIC) leads to wasting and multiple organ failure (Septic Shock)
B1 B Cells Function
Subpopulation of B-Cells
- Has a nonconventional surface phenotype
More for rapid response to infection (Does not have gene switching so can have a faster response)
B1 cells have a general affinity for bacterial polysaccharide antigens
Inflammatory Cytokines Actions and Result
- Hypothalamus
IL-1/IL-6/TNF-alpha causes an increase in body temperature
- Decreases bacterial/viral replication
- Increased antigen processing
- Facilitates adaptive immune response
Where are Mechanical Barriers found
Epithelial Cells joined by tight junctions
- Skin, Gut, Lung, Eye/Nose
Longitudinal flow of air or fluid
- Skin, Gut
Movement of mucus by cilia
- Lung
What is immunological memory
After the primary immune response has cleared the infection a long-term protective immunity is established
- Provokes a faster and stronger secondary immune response when encountering the same infection
What are Virally-Induced Cytokines
When human cells are infected by a virus they are then stimulated to produce Type 1 Interferons
Inflammatory Cytokines Body Heat Mechanism
Acts on hypothalamus to raise body temperature (IL-1, TNF-alpha) causing fever (pyrogenic)
- Increases metabolism to burn more energy creating heat
What kind of organisms can evade adaptive immunity
Highly mutable viruses only present very little of the original antigen
- However, the body will prioritize antigens it has seen before and will constrain any processing for new antigens