L16 Types Of Immune Responses 1&2

Question 1

Whats a hypersensitivity reaction

Answer 1

Exaggerated response to a harmless antigen Due to imbalance between effector and regulatory mechanisms

Question 2

Who does hypersensitivity affect

Answer 2

Individuals who have been previously exposed to an antigen and manifest detectable reaction to that antigen

Question 3

Describe type 1
Ag
Ab 
Effector cells
Chemical mediators

Answer 3

Rapidly developing
Known as allergy or anaphylactic reaction
Antigen: exogenous
Ab: igE dependent upon th-2 cells
Effector cells: mast cells in tissue and basophil in blood
Effector chemical mediators: histamine,leukotrienes,prostaglandins,eosinophils and platelets activating factor

Question 4

Describe the early phase of type 1

Answer 4

Develop 5-30 mins after exposure
T helper 2 cells stimulated and IgE is produced in genetically susceptible individuals
IgE binds to Fc receptors on mast cells

Question 5

What happens after second exposure in type 1 early phase

Answer 5

IgE activates mast cells to degranulate and secrete primary mediators
Redness, swelling, edema, inc secretion and smooth muscle contractions

Question 6

What is an allergy

Answer 6

Abnormal adaptive immune response that may or may not involve antigen specific IgE

Question 7

What is atopy

Answer 7

Genetically determined susceptibility to allergic reaction

Show inc of serum igE and inc IL4 secreting th2 lymphocytes

Question 8

What are atopy patients susceptible to

Answer 8

Allergic rhinitis
Asthma
Atopic dermatitis

Question 9

Describe the last phase of type 1

Answer 9

4-12 hours after early phase
Mediated by eosinophils,neutrophils, lymphocytes
Th2 cytokine il5 is most potent eosinophil activating cytokine
Cause tissue damage and late phase inflammatory reaction

Question 10

Why causes Anaphylactic shock and what are its symptoms

Answer 10

Fatal state
Occurs in sensitized individuals following injection of foreign proteins, hormones,enzymes, polysaccharides, drugs or exposure to food allergens or insect toxins

Itching,hives, skin erythema, striking contraction of respiratory bronchioles and respiratory distress,laryngeal edema results in hoarseness and further compromises breathing

Question 11

Describe localized hyper sensitivity

Answer 11

Involving epithelial surface at the site of allergen entry,hay fever,bronchial asthma, bronchospasm,food allergy and atopic dermatitis and allergic conjunctivitis

Question 12

Type that plays a role against parasitic infections

Answer 12

1

Question 13

Describe type 2

Answer 13

Cytotoxic hypersensitivity
Ab react with antigens present on cell surfaces or in extracellular matrix
Antigen: endogenous or exogenous
Ab:mainly igG but can also be IgM
Effector cells: neutrophils, macrophages,eosinophils, and Nk cells

Question 14

What are the mechanisms involved in type 2

Answer 14

Opsonization and phagocytosis
Complement and fc receptor mediated inflammation
Ab mediated cellular dysfunction

Question 15

Describe opsonization and phagocytosis

Answer 15

Ab coat cell surface of ag associated with blood typing found on RBCs
Coating leads to activation of complement cascade and lysis as well as phagocytosis

Question 16

What are the clinical examples for opsonization and phagocytosis

Answer 16

▪️Hemolytic transfusion associated with mismatched blood transfusion reaction
▪️Hemolytic disease in new born(rh-ve mother and rh+ve fetus)
▪️autoimmune anemia
▪️drug reaction

Question 17

Describe the complement and fc receptor mediated inflammation

Answer 17

Ag-ab binding leads to activation of complements and recruitment of macrophages and neutrophils mediating an acute inflammatory reaction through release of proteases and reactive oxygen species

Question 18

Clinical example for complement and fc receptor mediated inflammation

Answer 18

Transplant organ rejection

Skin rash due to drug reaction

Question 19

Describe ab mediated cellular cytotoxicity

Answer 19

Autoab bind to cell surface receptors

Produce abnormal activation/blockade of signaling process