Immune System in Disease

Question 1

What are the 4 types of hypersensitivity?

Answer 1

type 1: immediate - allerg
type 2: antibody mediated
type 3: immune complex
type 4: delayed type

Question 2

What is type 1 immediate hypersensitivity mediated by?

Answer 2

IgE, mast cells, lipid mediators

Question 3

What is type 4 delayed type hypersensitivity mediated by?

Answer 3

CD4 T cell mediated

Question 4

What response do allergens induce?

Answer 4

Th2 reponse
low dose, mucosal location

Question 5

What are 3 properties of allergens?

Answer 5

1. very stable
2. high solubility in bodily fluids
3. introduced in low doses

Question 6

What are 4 allergic reactions?

Answer 6

1. systemic anaphylaxis
2. allergy rhinitis
3. asthma
4. food allergiesW

Question 7

What are the 2 phases of type 1 immediate?

Answer 7

1. sensitisation
2. response (local or systemic)

Question 8

What are the 3 steps in sensitisation?

Answer 8

1. allergen cleaves occluding in tight junctions, entering mucosa
2. DC primes T cell in lymph node
3. plasma cell travels back to mucosa and produces IgE specific Ab

Question 9

What is the response step?

Answer 9

allergen-specific IgE binds to mast cell, triggering degranulation

Question 10

What are 3 results of mast cell activation?

Answer 10

1. secretion of preformed mediators
2. synthesis and secretion of lipid mediators
3. synthesis and section of cytokines

Question 11

What are 2 physiological effects of mast cell degranulation in the GI tract?

Answer 11

1. increased fluid secretion and peristalsis
2. diarrhoea, vomiting

Question 12

What are 2 physiological effects of mast cell degranulation in the airways?

Answer 12

decreased diameter, more mucus
wheezing, coughing, phlegm

Question 13

What are 2 physiological effects of mast cell degranulation in the blood vesesls?

Answer 13

more blood flow and perm
more fluid to tissues, lymph flow and effector response

Question 14

What happens during the immediate phase?

Answer 14

wheal and flare
blood vessels dilate, leak plasma
more swelling around site of challenge (wheal)
blood vessels further dilate (flare)

Question 15

What happens in the late phase?

Answer 15

involve cell infiltrates and sustained edema and/or smooth muscle contraction

Question 16

What are the 2 outcome of type 2 hypersensitivity?

Answer 16

1. injury dur to activation of effector mechanisms
2. abnormal physiological response (graves, MG)

Question 17

What causes type 3 hypersensitivity?

Answer 17

occurs if complexes are excessively produced and inefficiently cleared

Question 18

What are 4 results of immune complex mediated damage?

Answer 18

1. immune complexes deposit on basement membranes and blood vessel walls
2. vasculitis
3. glomerulonephritis
4. arthritis

Question 19

what elicits type 4 hypersensitivity?

Answer 19

1. microbial infection
2. intradermal injection of protein antigens
3. contact with chemicals

Question 20

What are the two phases of type 4 hypersensitivity?

Answer 20

1. sensitisation
   2 response

Question 21

explain sensitisation in type 4

Answer 21

allergen penetrates skin and is taken up by local antigen
DC primes T cell in LN

Question 22

explain response in type 4

Answer 22

re-exposure to antigen: Th1 recognises antigen and releases cytokines
recruitment and activation of phagocytes

Question 23

What is the Mantoux test?

Answer 23

inject PPD to detect presence of Mtb-specific CD4 T cells

Question 24

Why does gluten cause celiac?

Answer 24

gluten is a mix of glutamine and proline rich proteins
tTg converts glutamine into glutamic acid
gliding bind w high affinity to HLA-DQ2/8 resulting in T cell activation

Question 25

Why are autoreactive cells not always activated?

Answer 25

1. antigen not available 2. absence of signal 2 3. aitoreactive B cells don't have auto reactive CD4+ T cells

Question 26

Response to type 2/3

Answer 26

B cell production of auto antibodies

Question 27

CD4 and CD8 T cells

Answer 27

DTH responses (TH1 activation of macrophages, cytokine production, pro-inflammatory mediator disease CTL killing of stromal cells provision of B cell help

Question 28

macrophages

Answer 28

nitric oxide, proteases, oxidative radicals

Question 29

Summary of normal pituitary

Answer 29

pituitary gland releases TSH which acts on thyroid to release thyroid hormones thyroid hormones act on pituitary gland to shut down production of TSH, suppressing thyroid hormone synthesis

Question 30

What happens in graves?

Answer 30

autoantibodies bind to TSH receptor on thyroid cels stimulates receptor so enhanced production of thyroid hormones

Question 31

What is lupus?

Answer 31

unknown trigger many auto antigens B cell hyperactivity presence of anti-DNA autoantibodies and immune complex deposition in kidney

Question 32

What are 2 examples of t cell mediated autoimmunity?

Answer 32

1. insulin dependent diabetes mellitus (IDDM) 2. MS

Question 33

IDDM

Answer 33

organ spec., T cell med (CD4/CD8) destruction of pancreatic beta cells which produce insulin infiltration of lymphocytes, weak autoantibody response, T cell reactivity to islet proteins loss of insulin secretion, resultant insulin dependence

Question 34

MS

Answer 34

polygenic degenerative disorder of CNS which results in paralysis episodes while forming, and then chronic paralysis in late stages

Question 35

What T cells for MS

Answer 35

CD4 T cells specific for myelin antigens promote an inflammatory response and degrade myelin sheath Th1 nd Th17 responses = bad Th2 responses = remission

Question 36

2 categories of immunodeficiency?

Answer 36

1. primary immunodeficiency disorders (inherited) - gene mutations = immune system failure - X-linked, autosomal recessive 2. secondly immunodeficiency disorders (acquired) - infection, cancer, chemo, organ transplant - suppression of immune responses

Question 37

Treatment of immunodeficiencies

Answer 37

1. antibiotics 2. IVIG 3. enzyme replacement 4. bone marrow transplant

Question 38

XLA

Answer 38

mutation in gene for Btk Btw needed for signal transduction via pre-BCR failure to make complete BCR leads to pre-B cell apoptosis

Question 39

hyper IgM (x-linked)

Answer 39

x-linked hyper IgM syndrome is caused by mutations in CD40L = Defective CD40 signalling