Nelson- Hypersensitivity

Question 1

What is innate immunity?

Answer 1

Pre-existing, non-specific defense mechanism, present prior to infection. Evolved to recognize PAMPS and DAMPS and protect individual from infection.

Question 2

What is adaptive immunity?

Answer 2

Reactive mechanisms stimulated by specific microb capable of recognizing microbial and non-microbial substances.

Question 3

What are some of the component of innate immunity?

Answer 3

Epithelial barriers
phagocytic cells
Eosino, Baso, mast
NK
Plasma proteins (complement)

Question 4

What are the two types of adaptive immunity?

Answer 4

Humoral- extracellular microbes and toxins

Cell-mediated- intracellular microbes, tumor cells

Question 5

What are naive lymphocytes?

Answer 5

mature lymphocytes which haven’t yet encountered the antigen they’re specified for

Question 6

What are activated lymphocytes? (2 type)

Answer 6

differentiate into effector cells that eliminate the pathogen and memory cells that are reactivated upon second exposure.

Question 7

Function of CD4 T cell

Answer 7

Secrete cytokines, help B cells become plasma cells

Question 8

Function of CD8 T cell

Answer 8

kill virus infected cells, neoplastic and donor graft cells

Question 9

Function of B lymphocyte

Answer 9

differentiate into plasma cells that produce IG to kill encapsulated bacteria and act as APCs w/ CD4 cells

Question 10

Function of NK

Answer 10

kill virus infected and neoplastic cells

release IFNy

Question 11

Function of macrophage

Answer 11

phagocytosis and cytokine production

APCs for T cells

Question 12

Function of DC

Answer 12

APCs to T cells

Question 13

What are generative lymphoid organs?

Answer 13

Sites where T and B lymphocytes mature and become competent to respond to antigens

Question 14

What are peripheral lymphoid organs?

Answer 14

Sites where the adaptive IR is initiated (lymph nodes and spleen)

B cells in follicles
T cells in paracortical regions

Question 15

HLA-A, B and C genes code for what class of MHC. What does that MHC do?

Answer 15

MHC I
Display proteins derived from the cytoplasm
Recognized by CD8 T lymphocytes and NK cells

Question 16

HLA-DP, DQ, DR genes code for what class of MHC. What does that MHC do?

Answer 16

MHC II
Display antigens that have been internalized into vesicles
Recognized by CD4 T lymphocytes

Question 17

What are the two reasons we do HLA testing?

Answer 17

Diseases are associated w/ the inheritance of HLA alleles. HLA testing is used to determine disease risk.
HLA testing is also used in transplantation work up. Close matches increase chances of graft survival.

Question 18

What is a hypersensitivity reactoin?

Answer 18

Individuals previously exposed to an antigen are sensitized. With second exposure some ppl develop pathologic immune response to antigen.

Question 19

What are the 4 types of hypersensitivity reacionts?

Answer 19

Immediate
Anti-body mediated
Immune complex mediated
Cell mediated

ACID- Allergic, Cell-mediated cytotoxic, immune complex, delayed

Question 20

What is a type I hypersensitivity rxn?

Answer 20

FIRST and FAST
Rapid rxn occuring w/in minutes after Ag binds Ab bound to mast cells.
Occurs in individuals previously sensitized to the antigen.
Mediated by IgE Ab dependent activation of mast cells.

Question 21

What is atopy?

Answer 21

The predisposition to develop localized immediate hypersensitivity rxns.

Positive family hx is found in 50% of individuals.

Question 22

Atopic individuals tend to have what two things…

Answer 22

Higher IgE levels and more IL-4 producing Th2 cells.

Question 23

What is the mechanism of a type 1 hypersensitivity rxn?

Answer 23

Introduction of allergen>
stimulates Th2 response and IgE production>
IgE binds to Fc receptors on mast cells>
Subsequent exposure to allergen activates mast cells to secrete mediators responsible for the immediate and late-phase rxns

Question 24

What is the immediate phase in type 1 rxn?

Answer 24

vasodilatoin
congestion
edema

Question 25

What is the late phase in a type 1 rxn?

Answer 25

inflammatory infiltrate filled w/:
eosinophils
neutrophils
T cells

Question 26

What is a localized allergic rxn?

Answer 26

Something that sticks to one spot!

Question 27

What are common examples of localized allergic rxns?

Answer 27

allergic rhinitis (hay fever)
bronchial asthma
urticaria (hives)
allergic gastroenteritis (food allergy) (pollens, molds, house, dust, animal dander, food, medications, blood products, venom)

Question 28

How do you tx and prevent localized rxns?

Answer 28

Avoid allergen.
Use medications that inhibit the release of histamine from mast cells.
Immunotherapy

Question 29

What is systemic anaphylaxis?

Answer 29

Life threatening allergic reaction characterized by vascular shock, widespread edema, difficulty breathing (d/t massive mast cell activation)

Question 30

What is the mechanism of systemic anaphylaxis?

Answer 30

Massive mast cell activation–> vasoactive amines released in mins
Death in mins> d/t upper airway edema and respiratory failure from bronchial constriction/shock

Question 31

What are common inciting agents in fatal systemic anaphylaxis?

Answer 31

Therapeutic agents (beta-lactam antibiotics-penicillin, cephalosporins, radiocontrast agents)

Food products (peanuts, seafood)

Insect toxin (bee/wasp sting)

Latex allergy

Question 32

What is a type II hypersensitivity rxn?

Answer 32

Antibodies react w/ antigens intrinsic to cell membrane/matrix or w/ exogenous antigens that are on the cell surface.

Question 33

What is the mechanism of injury of a type II rxn?

Answer 33

1. Opsonization of cells by Ab and complement components and ingestion by phagocytes
2. Inflammation induced by Ab binding to Fc receptors of leukocytes and by complement breakdown products
3. Anti-receptor Ab disturb the normal fxn of receptors.

Question 34

What are some examples of a type II rxnn?

Answer 34

Myasthenia gravis- ACh receptor
Autoimmune hemolytic anemia (RBC membrane proteins)
Autoimmune throbocytopenic purpura (platelet proteins–> bleeding)
Penphigus vulgaris (desmosomes)
Vasculitis (activation of neutrophils to release granules proteins leading to vasculitis)
Acute rheumatic fever
Graves disease

Question 35

What is good pasture’s syndrome

Answer 35

Antibodies act against the glomeruli basement membrane in the kidney’s and alveoli in the lungs. It’s possible to detect the Abs for diagnostic purposes.

Question 36

What is a type III hypersensitivity?

Answer 36

Cause by Ag-Ab complexes which cause inflammation at sites where they’re deposited.

Question 37

How do the Ag-Ab complexes cause injury in type III hypersensitivity?

Answer 37

When there is excessive Ab production in circulation the complexes become deposited on the vessel walls. The Fc receptor is bound by a WBC and the vessels are part of the collateral damage from the complex destruction.

Question 38

What are some examples of this type of rxn?

Answer 38

SLE
Postreptococcal glomerulonephritis
Reactive arthritis
Polyarteritis nodosa
Serum sickness

Question 39

Why are the clinical manifestations of type III hypersensitivity so diverse?

Answer 39

Because we have Abs to many different things…?

Question 40

Define type IV hypersensitivity.

Answer 40

Caused by T cell mediated immunity (NO Abs!)
T cells (CD4/8) are sensitized to exog/endog antigens. T cell immune response to these antigens--> tisue injury.

Question 41

How does type IV hypersensitivity injure the body?

Answer 41

Delayed type rxn- repeat exposure to the antigen the CD40Th1 cells respond to tissue antigens by secreting cytokines that stimulate inflammation and activate phagocytes–> tissue injury.

T cell mediated cytotoxicity–TK cells (CD8 directly kill tissue cells)

Question 42

What is the mechanism of granuloma formation?

Answer 42

CD4 T cells surround an area and release cytokines

Question 43

What are examples of type IV hypersensitivity?

Answer 43

Mantoux Test
Type I diabetes
MS
Rheumatoid arthritis
Chrons
Peripheral neuropathy; Guillian Barre
Contact sensitivity