Adaptive Immunity

Question 1

Function of APCs

Answer 1

Capture
Processing
Presentation

Question 2

Give examples of APCs and where they are found

Answer 2

Langerhan’s in skin
Dendritic cells in lymph nodes, mucosal membranes and blood
B cells in lymph tissue
MAcrophages in many

Question 3

How to APCs recognise pathogens

Answer 3

Pathogen Associated Membrane Patterns are recognised by Pattern Recognition Receptors on the APC
Extracellular pathogens by extracellular PRRs
Intracellular ones by intracellular PRRS

Question 4

How are extracellular microbes dealt with

Answer 4

PAMP –> PRR –> Humoral immunity (antibodies complement)

Question 5

How are intracellular microbes dealt with

Answer 5

PAMP –> PRR –> Cellular immunity

Question 6

What is an MHC

Answer 6

Major Histiocompatibility Complex
Set of surface molecules that bind to peptide fragments derived from pathogens and display them on cell surface for recognition by T cells
Mediate interaction of leucocytes
Determine donor compatibiltiy and susceptibility to immune diseas

Question 7

What are MHC called in humans

Answer 7

Human Leucocyte Antigen

Question 8

Describe MHC class I. Found where, present which peptides? Present to?

Answer 8

Found on all nucleated cells
Present peptides from intracellular microbes
Brings viral fragment to surface
Present to CD8+

Question 9

Describe MHC class II. Found where, present which peptides? Present to?

Answer 9

Found on dendritic cells, marocphages, B cells, APC
Present extracellular microbe peptides
Stimulate CD4+ –> B cell antibody production

Question 10

Describe the endogenous pathway in MHC class I

Answer 10

Virus replicates and produces proteins
Proteins recognised as useless and cleaved by proteosome
Small peptide fragments transported into ER where MHC class I bind if there is a match
This complex can migrate to cell surface and await recognition by CD8+

Question 11

Describe the MHC Class II exogenous pathway

Answer 11

PRR recognises PAMP
Microcytosis of exogenous antigen from extracellular microbes
Cleaved using phagolysosome
Digested into small peptides
Endosome has MHC II
Match - complex formed
Moves to cell surface to present to CD4+

Question 12

How does HLA determine HIV progression

Answer 12

Slow progressor
- HLA molecules present peptide key to viral survival that cannot mutate –> Effective response
Rapid progressor
HLA presents a peptide that can be mutated - difficult to mount an effective response

Question 13

What leads to autimmune disease

Answer 13

Cross reactivity between host and microbial antigens

E.g. T1DM Coxsackie and Islets of Langerhans

Question 14

Desctibe th receptors on T cells

Answer 14

All have T cell receptor for binding MHC processed peptide and CD3 receptor for signal transduction
CD4+ have CD4 receptor from MHC II
CD8+ have CD8 for MHC I

Question 15

Binding of Naive CD4

Answer 15

CD4 binds to MHC class II on APC
T cell receptor binds to the MHC peptide
CD28 binds to B7

Question 16

Describe the primary antibody reaction

Answer 16

IgM Opsonises
Some IgG
Reflect naivity to pathogen

Question 17

Describe the secondary antibody reaction

Answer 17

IgG
Some IgM, larger total amount
Opsonin, activates complement, initiates antibody dependent cytotoxicity

Question 18

IgA

Answer 18

Mucosal immunity

Question 19

IgE

Answer 19

Allergic reaction mast cell degranulation

Question 20

TH1 cells activate

Answer 20

CD8+
B cells to produce antibodies
MAcrophages

Question 21

TH2 cells actiate

Answer 21

Eosinophils
B cells to release antibodies
Mast cellsfor local inflammation

Question 22

Lung colonisation in CF

Answer 22

Haemophilus influenza
Staph aureus
Pseudonomas aeruginosa
Atypical mycobacteria
Candida albicans
Aspergillus