Effector Mechanisms Of Adaptive Immunity

Question 1

Antibody neutralisation

Answer 1

Blocks molecules important to pr neutralises the function of the pathogen by binding to the active part of the pathogenic cell

Question 2

Complement activation

Answer 2

IgM and IgG can activate the classical complement pathway

-> which 1. Directly loses bacteria 2. Opsonises cells for uptake by phagocytes 3. Activates the immune response

Question 3

Opsonisation

Answer 3

Phagocytes have receptors on their surface for antibodies (Fc receptors and complement)
If a pathogen has antibody and or complement deposited on its surface it is opsonised

Question 4

Antibody dependent cell cytotoxicity

Answer 4

Infected cells have pathogen molecules on their surface -> Antibodies bind and mark them for killing -> NK cells ands neutrophils recognise antibodies and tell the cells to apoptosis via release of cytotoxic granules

Question 5

Mobilisation of inflammatory mediators

Answer 5

Mast cells have high affinity Fc epsilon receptor 1 which binds free IgE -> When FCR1 receptors are criss linked, mast cells and basophils degranulate and rapidly release inflammatory compounds

Question 6

B cell activation leads to class switching

Answer 6

Antibody function is determined by Fc region - termed isotopes

Naive B cells first express IgM

Activated B cells can switch (change constants region to ,ark IgG, IgA and IgE)

Question 7

Antibody Fc receptors

Answer 7

Distinct Fc receptors for each isotope on immune cells for antibodies

Question 8

IgG

Answer 8

Monomeric

Action depends on subclass, but can opsonise, neutralise, activate complement and antibody dependent cell cytotoxicity

Question 9

IgM

Answer 9

Dimeric

First isotope to be produced
Great for trapping and neutralising lots of antigen, very good at activating complement, poor at opsonising and antibody dependent cell cytotoxicity

Question 10

IgE

Answer 10

Monomeric
Best at activating basophils, mast cells an eosinophils
In allergy and parasite infections

Question 11

IgA

Answer 11

Dimeric

Found in mucosa
Good at neutralising intestinal pathogens and ensuring they are flushed out
Poor at activating complement, opsonising and ADCC (as there is no neutrophils in the gut lumen)

Question 12

Somatic hypermutation

Answer 12

Point mutations in variable regions of receptor/antibody

Activated B cells undergo this

Leads to antibodies with stronger or weaker binding to antigen

Question 13

Affinity maturation

Answer 13

Generates antibodies that can bind strongly to monovalent antigens

Question 14

CD4+ T helper cells

Answer 14

Act as a co-ordination for killing cells
T cells which when activated by dendritic cells carrying their specific antigen proliferate then go to B cell area to provide help by providing co-stimulation signal - they select B cells that make the strongest binding antibodies

CD4+ T cells select appropriate class of antibody during class switching

CD4+T cells stimulate innate cells

Question 15

Linked recognition

Answer 15

CD4+ T cells only provide help to B cells which recognised the same antigen as them and present that peptide on MHC class two

Question 16

Linked recognition prevents

Answer 16

CD4+ T cells helping B cells that recognise self/environmental conditions

Question 17

CD8+ cytotoxic T lymphocytes kills through

Answer 17

FAS litigation and perforin and grant me release

Fas litigation directly signals to induce apoptosis
Perforin forms pores allowing granzyme to enter
Granzyme activates caspases, DNAase activation and mitochondrial breakdown

Question 18

Cross presentation

Answer 18

Intial activation of MHC 1/ peptide on dendritic cell leads to activation in lymph node

Question 19

Natural Killer cells

Answer 19

Recognise down regulation of expression of MHC1 and kill cell