3.3 Autoimmunity

Question 1

Type __ hypersensitivity reactions are initiated by Ag-Ab complexes which can induce an inflammatory response/complement system

Answer 1

III

Question 2

what type of reaction is Arthus reaction an example of?

Answer 2

Type III, local

Question 3

what is a systemic type III reaction?

Answer 3

Ag-Ab complexes circulate in bloodstream and settle in target organs and initiate an inflammatory response

Question 4

Continuous buildup of Ag/Ab complexes can lead to ______

Answer 4

autoimmune disease

Question 5

what are the 3 categories of immune complex lesion diseases?

Answer 5

1. infectious/post-infectious disease
2. auto-immune disease
3. drug reactions

Question 6

Renal disease, Streptococcal infections, Syphilis, and Hepatitis B are all examples of what kind of immune complex lesion diseases?

Answer 6

Infectious and post-infectious disease

Question 7

Lupus and rheumatoid arthritis are all examples of what kind of immune complex lesion diseases?

Answer 7

autoimmune diseases

Question 8

how do RBCs play a role in removal of immune complexes?

Answer 8

1. IgG in fixed complement can attach to CRI receptor on RBC
2. it can interact with C3b
3. will circulate and come in contact with kupffer cell
4. it will then be destroyed

Question 9

the sites of type ___ hypersensitivity reactions are the skin or mucosa

Answer 9

IV

Question 10

what kind of cells are involved in Type IV reactions?

Answer 10

CD4+TH1, cytokines, CD8+ cytotoxic T cells

Question 11

what is the time frame for type IV rxns?

Answer 11

24-72hrs

Question 12

Tuberculin, contact dermatitis, contact stomatitis, are all examples of type ___ reactions

Answer 12

IV

Question 13

what are the steps of a tuberculin reaction?

Answer 13

1. Antigen introduced into subcutaneous tissue → processed by APCs
2. TH1 recognizes antigen and releases cytokines →
3. recruitment of phagocytes, fluid, etc to site of antigen

Question 14

what do these cytokines do in a tuberculosis reaction?
1. Chemokines
2. IFN-gamma
3. TFN-alpha & LT

Answer 14

1. recruit macrophages
2. activate macrophages
3. tissue destruction

Question 15

what are the steps of contact hypersensitivity?

Answer 15

1. something comes in contact with skin (hapten)
2. haptens go into epidermis where they interact with langerhan cells
3. processed and go to lymph node
4. will become dendritic cell and present antigen to CD4+ T cell → effector cell
5. effector cell will interact with the macrophage and releases cytokines
6. keratinocytes activated

Question 16

what are the reaction times for these?
1. contact hypersensitivity
2. tuberculin
3. granuloma
4. IgE
5. Arthur

Answer 16

1. 24-72h
2. 24-72h
3. 21-28 days
4. <30min
5. 5-6hr

Question 17

what are some examples of contact hypersensitivity?

Answer 17

nickel, poison ivy

Question 18

what happens in a poison ivy reaction?

Answer 18

1. Pentadecatechol penetrates cell membrane and modifies intracellular proteins
2. proteins broken down and become incorporated into MHC1
3. MHC1 recognized by CD8+ cells
4. this causes overall reaction

Question 19

what type of MHC do we see in a poison ivy reaction?

Answer 19

MHC1

Question 20

what type of T cells are seen in a granuloma reaction?

Answer 20

CD4 TH1

Question 21

Granuloma is a multinucleated giant cells with _____ cells in center, surrounded by T-cells

Answer 21

epitheliod

Question 22

what are the steps of a granuloma forming?

Answer 22

1. APC + Naive T cell = IL-12 produced to stimulate T cell
2. T cell proliferation, CD4 TH1+
3. Activation of immature macrophages
4. Macrophage changes in morphology to look like epithelial cells
5. Epithelioid cells fuse and form multinucleated giant cell
6. These form granuloma

Question 23

in a granuloma reaction ______ changes in morphology to resemble a _____ cell

Answer 23

macrophage, epithelial

Question 24

______ is a response to self antigens due to lack of tolerance, response MAY NOT be harmful

Answer 24

Autoimmunity

Question 25

____________ is a loss of tolerance to a self antigen that results in an immune response that WILL produce a clinical disease

Answer 25

Autoimmune disease

Question 26

what are the mechanisms of self tolerance?

Answer 26

1. Negative selection of B cells 2. Negative selection of T cells in thymus 3. Sequestered antigens 4. suppression of autoimmune response by Treg 5. central tolerance

Question 27

RBC removal of immune complexes is efficent for ___ but not ____ immune complexes

Answer 27

IgG, IgA

Question 28

how can Treg get rid of self-reactive cells?

Answer 28

Treg has to attach to same APC as CD4 cell→ it will interact with TCR and MHC → then it will release cytokines that kills self-reactive CD4 cell

Question 29

1. Cd28/B7 + specific signal = 2. Only specific signal = 3. Only Cd28/B7 =

Answer 29

1.activated T cell 2. anergic T cell 3. no effect on T cell

Question 29

1. Cd28/B7 + specific signal = 2. Only specific signal = 3. Only Cd28/B7 =

Answer 29

1.activated T cell 2. anergic T cell 3. no effect on T cell

Question 30

Autoimmune diseases are more prevalent in females than males, except for which disease?

Answer 30

ankylosing spondylitis

Question 31

what are some possible causes of autoimmune diseases? (6)

Answer 31

1. Cross reacting antigens 2. Breakdown in lymphocyte regulation 3. Microbes 4. Sequestered antigens 5. Environmental 6. Genetic

Question 32

what is an example of a cross-reacting antigen that can cause an AID? what can it cause?

Answer 32

streptococcus antigen, rheumatic fever

Question 33

Strep uses _______ to cause loss of self-tolerance, interactions with myocardial tissue, and rheumatic fever

Answer 33

molecular mimicry

Question 34

a breakdown in lymphocyte regulation causes loss of ___ cells

Answer 34

Treg

Question 35

have we been able to ID microbes that are associated with human models for human AIDs?

Answer 35

NO, just animals

Question 36

________ are antigens not exposed to IS during immunological development

Answer 36

Sequestered antigens

Question 37

what are 2 examples of sequestered antigens?

Answer 37

1. selective IgA deficiency 2. trauma to eye releases sequestered antigen → carried to lymph and activate T cell → effector T cells return and attack BOTH eyes