IMMUNOLOGY

Question 1

ROLES OF THE IMMUNE SYSTEM (2)

Answer 1

prevent infection

eradicate infections/damage

Question 2

Functions of immunity (2)

Answer 2

RECOGNITION FUNCTIONS – Damage/Danger

EFFECTOR FUNCTIONS – eliminate danger/damage

Question 3

characterise INNATE IMMUNITY (4)

Answer 3

First line of defence
Immediate
Non specific
No memory

Question 4

characterise ADAPTIVE IMMUNITY (4)

Answer 4

Secondary
Needs time (days)
Specific
Memory

Question 5

blanket protection is provided by (3):

Answer 5

phagocytic cells
degranulating cells
secreted proteins

Question 6

Phagocytic cells (tissue and circulating) do 2 things:

Answer 6

Orchestrate initiation of response

Recognise, ingest and kill bacteria and yeasts

Question 7

Degranulating cells (tissues and circulating) do 2 things:

Answer 7

Orchestrate initiation of response

Damage and kill multicellular parasites and viruses

Question 8

Secreted proteins - list 3 types:

Answer 8

Complement (induced)
Chemokines
Cytokines

Question 9

define ANTIGEN

Answer 9

A foreign substance which when encountered and recognised by the immune system causes an immune response

Question 10

immune system recognises (2):

Answer 10

Molecular patterns (innate)
Antigenic determinants or epitopes (adaptive)

Question 11

Leukocytes (1x10^7/ml) are comprised of 3:

Answer 11

granulocytes - 70%
lymphocytes -20-30%
monocytes - up to 10%

Question 12

Chemokines/Chemotaxis

Answer 12

Chemokines/Chemotaxis
Chemokines are small proteins that induce chemotaxis - IL-8
Chemotaxis is the migration of cells along a chemical gradient
Usually from a site of low concentration to one of higher concentration
Phagocytes have receptors for chemotactic agents
Binding of chemotactic agent controls migration
At high chemoattractant concentration, cells become very adherent and stop migrating

Question 13

ADAPTIVE IMMUNE SYSTEM

Answer 13

ADAPTIVE IMMUNE SYSTEM
The main mechanism by which we eradicate infection
Powerful and sophisticated
Improve over time to specifically fight different infections more effectively (memory)
Cost of the complexity it takes time to develop (days/weeks)
All infection is a race between the immune response and the invading pathogen
Innate and Adaptive must work together

Question 14

important characteristics of ADAPTIVE IMMUNE SYSTEM

Answer 14

IMPORTANT CHARACTERISTICS
Cells called lymphocytes
Can adapt to all invading organisms having almost infinite range of responses.
Highly specific - antigen receptors
Has a memory…. Vaccination

Question 15

PRIMARY AND SECONDARY RESPONSES

Answer 15

PRIMARY AND SECONDARY RESPONSES
The key to the power of the adaptive immune system is its MEMORY
Memory increases and improves (humoral immunity) with repeated exposure to antigen
Memory may be lifelong
Pathogens adapt to avoid memory by changing their immunological appearance e.g. influenza

Question 16

LYMPHOID LINEAGE

Answer 16

LYMPHOID LINEAGE
Arise in the bone marrow from pluripotential stem cells.
Differentiation is controlled by soluble factors
Leave bone marrow at specific stage of maturity
40-60% go to the THYMUS maturation and education ➡️ T lymphocytes
20% remain in bone marrow maturation ➡️ B lymphocytes.
further 10-20% remain in bone marrow and mature into NK (natural killer) cells

Question 17

CELLULAR IMMUNITY

Answer 17

CELLULAR IMMUNITY
T lymphocytes (thymus)
Three main types T helper, T cytotoxic, T regulatory.
T helper cells direct the adaptive immune response. The control cell (HIV)
T helper cells also have direct effector functions through mediators- cytokines and receptors- intracellular bacteria
T cytotoxic cells directly kill virally infected cells- effector cell
All require another specialised cell for antigen recognition- the antigen presenting cell (APC)

Question 18

Two arms to the adaptive immune response

Answer 18

Cellular Immunity

Humoral Immunity

Question 19

HUMORAL IMMUNITY

Answer 19

HUMORAL IMMUNITY
B lymphocytes (Bone marrow)
Most B lymphocyte function requires help from T helper cells
Humoral immunity is effective at removing organisms which live outside our cells
Very effective for neutralising invading bacteria/toxins
Effector molecule Antibodies
Interacts with Complement cascade and phagocytes/degranulators

CLONAL EXPANSION
LYMPHOBLAST
MEMORY CELLS

Question 20

CLONAL EXPANSION

Answer 20

B cells and T cells do not function unless they are activated.
Antigen is absolutely required for lymphocyte activation.
A single antigen specific activated clone divides

Question 21

LYMPHOBLAST

Answer 21

Activated lymphocytes look different, they have much larger cytoplasm very active in producing proteins

Question 22

MEMORY CELLS

Answer 22

B cells become terminally differentiated into plasma cells which secrete antibody
Some activated cells become MEMORY CELLS