Session 2 - Microbiome And Innate Immunity Flashcards by Jia Dhong Tan

What are the 6 factors to take into consideration when doing a model of infection?

Patient 
Pathogen 
Mechanism of infection 
Process of infection 
Management of patient
Patient outcome

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What is the definition of the immune system?

Cells and organs that contribute to immune defenses against infectious and non-infectious conditions

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What is the definition of an infectious disease?

When a pathogen succeeds in evading or overwhelming the host’s immune defenses

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What are the 4 main roles of the immune system?

Recognize pathogen
Contain or eliminate infection
Regulate its own activities
Remember pathogen

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What are 4 differences between innate and adaptive immunity?

Innate is immediate, adaptive is long lasting
Innate is not specific, adaptive is specific
Innate does not include memory, adaptive does
Innate has no change in intensity, adaptive does

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What are the 4 barriers of the first lines of defense?

Physical
Physiological
Chemical
Biological

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What is the function of the body’s first line of defense?

Prevent entry and limit growth of pathogens

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What are 3 examples of physical barriers?

Skin
Mucous membranes
Bronchial cilia

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What are 4 examples of physiological barriers?

Diarrhea
Vomiting
Coughing
Sneezing

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What are 2 examples of chemical barriers?

Low pH

Antimicrobial molecules

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What is an example of biological barriers?

Normal flora

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What is an example of a normal flora that inhabits the skin?

Staphylococcus aureus

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What is an example of a normal flora that inhabits the mouth and nasopharynx?

Streptococcus mutans

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What is an example of a normal flora that inhabits the GI tract?

E. Coli

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What are 3 ways clinical problems start due to normal flora?

Displaced from its normal location
Overgrows and becomes pathogenic when host becomes immunocompromised
In mucosal surfaces is depleted by antibiotic therapy

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What are 3 main types of phagocytes?

Macrophages
Monocytes
Neutrophils

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What are 3 functions of macrophages?

Phagocytosis
Present antigens to T cells
Produce cytokines and chemokines

What is the function of monocytes?

Travels in blood to infection site and differentiate into macrophages

What is the function of neutrophils?

Ingest and destroy bacteria, recruited by chemokines to site of infection

What is the function of basophils and mast cells?

Important in allergic responses

What is the function of eosinophils?

Defense against multi cellular parasites like worms

What is the function of natural killer cells?

Kill all abnormal host cells

What is the function of dendritic cells?

Present microbial antigens to T cells

What are 3 factors that allow phagocytes to recognize pathogens?

Pathogen-associated molecular patterns (PAMPs) on pathogens
Pathogen recognition receptors (PRRs) on phagocytes
Opsonins on microbial surfaces

What is the function of opsonins?

Proteins that bind to microbial surfaces to enhance attachment of phagocytes and clearance of microbes

What are 3 main types of opsonins?

Complement proteins Antibodies Acute phase proteins

What are 2 examples of complement proteins?

C3b | C4b

What are 2 examples of antibodies?

IgG | IgM

What are 2 examples of acute phase proteins?

C-reactive protein | Mannose-binding left in

What kind of bacteria requires opsonization to clear?

Encapsulated

What are 3 examples of encapsulated bacteria?

Streptococcus pneumoniae Neisseria meningitidis Haemophilus influenzae b

What are the 2 main types of phagocyte intracellular killing mechanisms?

Oxygen dependent pathway - respiratory burst using free oxygen radicals Oxygen independent pathway - digestion using enzymes

What is the function of the complement system?

Part of the immune system that enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism

What is the function of C3a and C5a?

Recruitment of phagocytes

What is the function of C3b?

Opsonization of pathogens

What is the function of C5-C9?

Killing of pathogens via membrane attack complex

What are the 3 different pathways that the complement system is activated?

Classical pathway Alternative pathway MBL pathway

How is the classical pathway initiated?

Antibody antigen interaction

How is the alternative pathway initiated?

Cell surface microbial constituents

How is the MBL pathway initiated?

When MBL binds to mannose containing residues of proteins found on many microbes

What are the 3 functions of cytokines or chemokines?

Chemoattraction Phagocyte activation Inflammation

What are 3 cytokines derived from macrophages?

TNFalpha, IL-1, IL-6