Immune System Overview

Question 1

What is reverse zoonosis

Answer 1

Human -> animal

Question 2

What is CFR?

Answer 2

Case fatality rate
Mostly estimates and can depend on death recording methods, are rarely uniform over all population (underlying conditions)
Can influence risk vs hazard perception

Question 3

Types of vaccines?

Answer 3

Live attenuated
Dead/subunit vaccines
Viral vectors

Question 4

Risk and benefit of live attenuated?

Answer 4

-usually work well due to induction of strong immunity
-carry risk due to live nature, particularly for immuno-compromised

Question 5

Risk and benefit of dead/subunit?

Answer 5

-Use part of microbe, usually safer
-don’t work as well as live attenuated and require adjuvants to induce strong protective immunity

Question 6

What is a viral vector?

Answer 6

Genetically engineered microorganism used to deliver component (Ag?) for vaccine induced protection

Question 7

Bad effects of immune system?

Answer 7

-immune pathology (collateral damage, allergies, autoimmunity)
-graft rejection
-metabolic diseases
-mental health

Question 8

Obesity and immune system?

Answer 8

Leanness associates to type II response, obesity associated with inflammation and type I response

Question 9

Immune system needs to:?

Answer 9

Detect pathogens, some of which not evolved yet
Distinguish harmful and harmless signals (pathogen Ag vs food)
Respond rapidly and eliminate pathogens using appropriate mechanism
Control strength of response to limit immune pathology

Question 10

Barriers in Skin?

Answer 10

Mechanical:
-epithelial cells joined by tight junctions
-longitudinal flow of air or fluid

Chemical:
-Fatty acids
-Beta defensins, lamellar bodies, cathelicidin

Microbial:
-Normal microbiota (colonise niche so pathogens have no room to grow)

Question 11

Barriers in Gut?

Answer 11

Mechanical:
-epithelial cells joined by tight junctions
-longitudinal flow of air or fluid

Chemical:
-Low pH
-enzymes (pepsin)
-alpha-defensins (cryptidins)
-RegIII (lecticidins)
-cathelicidins

Microbial:
-Normal microbiota

Question 12

Barriers in lungs?

Answer 12

Mechanical:
-epithelial cells joined by tight junctions
-movement of mucus by cilia

Chemical:
-pulmonary surfactant
-alpha-defensins
-cathelicidin

Microbial:
-normal gut microbiota

Question 13

Barriers in eye/nose/oral cavity?

Answer 13

Mechanical:
-epithelial cells joined by tight junctions
-tears
-nasal cilia

Chemical:
-enzymes in tears and saliva (lysozyme)
-Histatins
-beta-defensins

Microbial:
-normal microbiota

Question 14

Pathogen methods of breaking barrier?

Answer 14

-Skin breaks, wounds, burns (Staphylococci, Streptococci, Clostridium tetani)(opportunistic)

-Animal bites (rabies)

-Insect bites (malaria, yellow fever, lymes disease)

-Parasites burrowing through skin (Schistosomes, hookworms)

Question 15

Mucosal barriers difference to skin

Answer 15

Have to let things in (nutrients, gas exchange)

Question 16

How does influenza exploit mucosal barrier?

Answer 16

Have receptors to bind and enter the cells, prevent ciliary motion to stop mucus movement out of body

Question 17

What infections involve mucosal barriers?

Answer 17

Placenta
Lungs
STIs
Faecal-oral
Food-borne

Question 18

Purpose of innate response?

Answer 18

Gives time for adaptive immunity to develop
Body is overwhelmed without an initial innate response

Need innate to adapt as innate can deal with certain smaller infections but as soon as a bigger one comes along body is overwhelmed

Question 19

Functions of innate immunity?

Answer 19

Sense and respond to danger signals

Always on for instant response

Communicate danger to other cells of innate and adaptive immunity

Recruit immune cells to infection site (inflammation)

Tell adaptive cells when to respond

Has cellular and biochemical killing mechanisms

Question 20

Innate killing mechanisms?

Answer 20

Phagocytosis (macrophage, neutrophil)

Secretion of cytotoxic granules (Eosinophils, neutrophils, mast cells)

Complement proteins (NK cells)

Question 21

Why does adaptive take time

Answer 21

Need to identify and expand T and B cells that recognise the pathogen

Question 22

Functions of adaptive immuntiy?

Answer 22

Helper T cell (Th): talk to other cells, coordinate immune responses, amplify innate immunity

Regulatory T cell (Treg): Turn off immune responses, prevent activation when not needed (allergy, infection over)

Cytotoxic T cells (CTL): kill infected cells

Question 23

Antibody function?

Answer 23

Neutralise pathogen molecules (toxins)
Mark pathogens for destruction
Link innate and adaptive killing mechanisms

Question 24

Adaptive memory response properties?

Answer 24

Specific to original pathogen
When that pathogen infects again response is faster and bigger as recognition of pathogen is still there

Combines speed and specificity

Question 25

How do innate and adaptive work together?

Answer 25

Innate: detects infection, identifies its type, activates and directs adaptive response, tells whether infection still present or cleared

Adaptive: cytokines activate innate cells to amplify innate killing, antibodies work with innate cells to recognise and kill pathogens, CTLs kill infected cells

Question 26

Methods of communication between cells?

Answer 26

Cytokines
Cell-cell communications (cell surface receptor ligand pairs)

Question 27

Cytokine properties?

Answer 27

Many different types w different functions

Target any cell with relevant receptor allowing one cell to target many and doesn’t require cell contact

Can fire in specific direction or all around and can act locally or systemically

Question 28

Cell-cell communication how?

Answer 28

Use receptor/ligand pairs on cell surface
Many diff receptors and ligands with diff functions

Cells need to be in contact and have correct receptor/ligand pairs

Allows precise communication between individual cells

Question 29

Lymph node and spleen properties?

Answer 29

Specialised sites where immune responses are coordinated
Focal points for immune cell communication
Play very important role in initiation of adaptive immune responses

Question 30

IBD cause?

Answer 30

Overzealous response against commensals