Immunology - Lecture 26

Question 1

What are the physical barriers, aka the 1st line of defence?

Answer 1

Skin - largest organ, its own microbe
Gut - lining also epithelial with barrier function
Cillia - hairs lining windpipe move mucus + particles from lung
Urine flow - flushes out pathogens

Question 2

What are the chemical barriers, aka the 1st lie of defence?

Answer 2

Tears - lysozyme (digest bacteria cell wall)
Mucus, saliva
Openings - secretion of anti-microbrial peptides/enzymes
Stomach acid - HCl secreted by parietal cells = lower pH, this activates proteases (pepsin)
Friendly bacteria - competition

Question 3

What causes Cystic fibrosis?

Answer 3

Cl- channel mutation causes thick mucus that cilia cannot move

Question 4

What is an example of a pathogen associated molecular patterns?

Answer 4

LPS in gram negative bacteria cell wall or peptides with formulated methionine (bacteria)

Question 5

What do damage associated molecular aterns do?

Answer 5

They identify damaged self cells

Question 6

Innate immunity in macrophages, dendritic cells and neutrophils/

Answer 6

Toll like receptors (TLRs) recognise PAMPs

This do this via a signal cascade via Junlfos TFs and NFRB, causing a change in gene expression

Question 7

What are myeloid and oymphoid cells invovled in?

Answer 7

Myeloid cell - innate protection
Lymphoid cells - adaptive immunity
WBC (leukocytes) - both myeloid + lymphoid cells

you’re born with it

Question 8

How do myeloid cells lead to a secondary response?

Answer 8

Myeloid cells (macrophages, dendritic cell) from monocytes + Neutrophils express TLR that recognise pathogenic signal

Cells recognise PAMPs and secrete molecular ligands that attract more immune cells

Question 9

How can we catch WBCs?

Answer 9

By dilating blood vessels and permeable and sticky endothelial ells

Question 10

What does swelling of blood vessels cause?

Answer 10

release of inflammatory cytokines (prostoglandins, histomines and cytokines)

Question 11

What does fever do to immunity?

Answer 11

inhibits proliferation and speed reaction

Question 12

What is sepsis?

Answer 12

Shock, loss of plasma volume, decreases Blood pressure, causes clotting and a cytokine storm

Question 13

What phagocytic cells are recruited during the second response?

Answer 13

Neutrophils - short lived(in blood not tissue), migrate to infection sites (puss)
Macrophages - long lived(areas likely to be exposed to pathogens e.. guts, airway)
Eisonophils - attack stuff too large for endocytosis

Question 14

What is the innate immune repsonse?

Answer 14

Micribes enter through break in skin and phagocytosed by dendritic cell

Activated dendritic cell carries microbial antigens to local lymphnode

Question 15

What is the adaptive immune response?

Answer 15

Activated dendrtitic cell activates to cells to respond to microbial antigens on dendritic cell surface

Question 16

How can we link innate and adaptive immunity?

Answer 16

Dendritic cells -> phagocytric cells from monocytes (large variety of TLRs)
Phagocytos pathogen, cleave into peptideswhich are bound to MHC proteins
DCs migrate to lymphoid tissue, activate T-cells of active immune systems

Question 17

What is adaptive immunity?

Answer 17

Generates specific responses to specifc pathogens
Identifys, target and destroys a vast range of pathogens/toxins

Question 18

What can be dandgerous about adaptive immunity?

Answer 18

Accidental targeting of self molecules dangerous (GVHD)

Question 19

How can lymphoid cells generate adaptive immunity?

Answer 19

Lymphoid cells develop in thymus and bone marrow (lymphoid organs). Drains into circulation
They migrate to secondary lymp. organswhere they are exposed to foreign antigens
B cells = bone marrow
T cells = Thymus

Question 20

WHat are natural killer cells?

Answer 20

Early defence from foreign material and autologous cells under stress e.g. infected (lymphoid cells) or undergoing tumour transformation

Question 21

What is an antibody reponse?

Answer 21

Secreted solublke immunoglobin binding to antigens.
They are produced by B-lymphocytes and secreted by plasma cells

Question 22

How many T-cell responses are there?

Answer 22

3 T-cells

Question 23

What is a Cytoxic T cell?

Answer 23

Directly kills infected host cells

Question 24

What is a Helper T cell?

Answer 24

Activate macrophages, dendritic cells, B-cells, C-T cells by secreting cytokines and displaying co-stimulatory proteins on surface

Question 25

What is a Regulatory T-cell?

Answer 25

Inhibits function of T-helper cells, C-T cells and dendrtic cells

Question 26

What are the steps of Antigen responses?

Answer 26

1. In development. library of lymphocytes generated (remain dormant)
2. When antigen presented, cells cells complementary are activated
3. INcread proliferation and clonal expansion (in vivo selection)
   Expansion occurs everytime an antigen is encountered
4. Triggers differentiation into effector cells
5. Subsequent encounter activate memory cells
   Boday can respond to many antogens at once

Question 27

Why is there lag after second encounter ?

Answer 27

Encounter is shorter to make respinse faster and stronger

Question 28

How much of plasma is made up of antibodies (immunoglobins)?

Answer 28

20%

Question 29

What are the 2 antogen binding sites?

Answer 29

2 ligt and 2 heavy chains

Question 30

oWhat are the 5 lasses of immunoglogins?

Answer 30

IgG
IgM
IgA
IgD
IgE
each has its own unique heavy chain and subclasses have their own hinge and tail

Question 31

How can antigen binidng sites allow antigens to bind?

Answer 31

Each chain has its own constant and variable domain

Question 32

What are antigen binding doamins made up of?

Answer 32

1 modified Ig domian and 3 hyper variable regions
3D structure of hypervariable domains vary
In vivo evolution to select best structure to interact with antigen