Immune memory

Question 1

What is immune memory?

Answer 1

• ability of immune system to respond more rapidly and effectively to pathogens previously encountered

Question 2

What is immune memory generated by?

Answer 2

generated from memory T cells and B cells

Question 3

Where are memory B cells found?

Answer 3

• in the lymph node

Question 4

What are the 3 different memory T cells?

Answer 4

1. T central memory cells
2. T effector memory cells
3. T resident memory cells

Question 5

Where are T central memory cells found?

Answer 5

• In tissues and circulation

Question 6

Where are T resident memory cells found?

Answer 6

• In tissues

Question 7

What is the 1st adaptive immune response to a pathogen?

Answer 7

• CD8 t cells migrate to the site of infection, where they kill infected cells
• early responding B cells produce and release virus-specific IgM antibodies

Question 8

What happens after the 1st initial adaptive response to a pathogen?

Answer 8

• CD4 T helper cells promote class-switching of germinal centre B cells from IgM to IgG or IgA virus specific antibody production

Question 9

What happens after virus clearances to IgG or IgA?

Answer 9

• After virus clearance a pool of memory IgG/IgA B cell and T cells remain and are rapidly reactivated upon reinfection with the same virus

Question 10

What does MALT stand for?
What does MALT do?

Answer 10

• mucosa associated lymphoid tissues
• regulates mucosal immunity

Question 11

What are the 3 different subcategories of MALT?

Answer 11

1. GALT (gut associated lymphoid tissue)
2. NALT (nasal associated lymphoid tissue)
3. BALT (bronchus associated lymphoid tissue)

Question 12

What vaccine targets BALT?

Answer 12

• vapourised vaccine delivery

Question 13

What vaccine targets NALT?

Answer 13

• nebulising vaccines

Question 14

What structure is important in GALT?

Answer 14

• Peyers patches

Question 15

What does GALT do?

Answer 15

• function as barrier against pathogen entry
• innate and adaptive immune responses occur

Question 16

What are the main stimulation sources of GALT?

Answer 16

• microbiota and dietary antigens
• DONT want to respond to these

Question 17

What is GALT?

Answer 17

• large population of plasma cells which secrete IgA and protect the barrier via immune exclusion

Question 18

What is the largest immune organ?

Answer 18

• GALT

Question 19

How do we get oral tolerance to food antigens and microbiota in GALT?

Answer 19

• through constant DC sampling of the lumen
• migrate to MLN to activate naïve T cells
• T cells Treg subset
• natural sate is tolerogenic

Question 20

What happens with T cells when pathogenic bacteria induce a proinflammatory state?

Answer 20

= effector T cells are generated

Question 21

How can pathogenic bacteria induce a proinflammatory sate?

Answer 21

• translocation of bacteria antigens from luminal space
• or invasion of bacteria

Question 22

What does the combined/ common mucosal system allow?
What is this system and what does it traffic?

Answer 22

• if you have a response at one mucosal site (inductive sites) , you get effector response at another site (effector site)
• system of linking mucosal surfaces of the body
• trafficking of lymphocytes between MALT sites

Question 23

What are the two types of immunity?

Answer 23

• passive
• Active

Question 24

What is passive immunity?

Answer 24

• derived from maternal transfer (in utero or via colostrum)

Question 25

What is active immunity?

Answer 25

- through innate and adaptive immune responses

Question 26

In ruminants (and all ungulates) there is no prenatal antibody transfer - What happens instead?

Answer 26

- IgG is deliver by bolus in the first 48 hours when the gut wall is still partially open

Question 27

In humans there is pre-natal antibody transfer - what is this?

Answer 27

- where IgG levels are equivalent between mother and foetus so have some protection before birth

Question 28

When is there a window of susceptibility of high risk after birth?

Answer 28

- when the passive immunity from the colostrum starts to wear off and the adaptive immune system is still coming into maturity

Question 29

Why do we not vaccinate while passive immunity is still in effect?

Answer 29

- as the antibody's from the mothers colostrum will destroy the vaccine before it can provide protection

Question 30

Even though calves and lambs are born with a functional immune system - why is colostrum still required?

Answer 30

- as high cortisol around birth diminished foetal immune responses and aids in colostrum uptake

Question 31

What does the foetal immune system develop without?

Answer 31

- it develops without external antigenic stimulation

Question 32

What is the route of post-natal passive immunity?

Answer 32

- via the gut

Question 33

What is the duration of maternal immunity?

Answer 33

= 2-4 weeks

Question 34

When does innate immunity develop?

Answer 34

- its limited after birth but develops quickly

Question 35

When does active (innate and adaptive) immunity develop from?

Answer 35

- develops from 6 weeks

Question 36

What is in colostrum?

Answer 36

- antibodies (IgG) - cytokines - cells

Question 37

Why are cytokines important in colostrum? When do they peak?

Answer 37

- develop immunity - activates phagocytes - peak 24-48 hrs post birth - enable gut microbiome

Question 38

What cells are in colostrum and when d levels peak?

Answer 38

- mostly leukocytes - predominantly macrophages - T cells > B cells - pathogen specific T cells - peak levels at 24 hrs post birth

Question 39

How does colostrum immunity work in ruminants?

Answer 39

1. protease activity in the digestive tract is low and there are trypsin inhibitors in colostrum 2. colostrum proteins are not degraded but can reach the small intestine 3. Colostral immunoglobulins bind to receptors on intestinal epithelial cells 4. immunoglobulin molecules are taken up by intestinal epithelial cells (pinocytosis) 5. absorbed immunoglobulins reach the bloodstream 6. Absorption is unselective and all classes of abs are absorbed 7. IgA us gradually excreted back to the mucosal surfaces

Question 40

What is neonatal isoerthrolysis?

Answer 40

- incompatibility of blood types between mother and offspring - cats, horses, pigs, dogs, cows

Question 41

What is neonatal isoerthrolysis characterised by?

Answer 41

- immune destruction of RBCs

Question 42

When does neonatal isoerthrolysis occur?

Answer 42

- occurs in postpartum period for animal with little/no placental transfer if IgG - when offspring ingests colostrum containing antibodies recognising RBC antigens

Question 43

When does feline neonatal isoerthrolysis occur?

Answer 43

- affects blood type A or AB new-born kittens who nurse in blood type B queen - When the B queens anti-A antibodies enter the kittens bloodstream they attack and destroy the kittens red blood cells

Question 44

What are the symptoms of Feline neonatal isoerthrolysis?

Answer 44

- dark red or brown urine - pale mucous membranes - jaundice - weak and lethargic - difficulty breathing