Hypersensitivity Reactions Flashcards

1
Q

Which type of hypersensitivty is called allergy

A

Type 1

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2
Q

Type 1 hypersentivity is mediated by

A

Binding of an allergen to IgE on the surface of mast cells
Th2 cells, IgE ab dependent activation of mast cells and leukocytes

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3
Q

Type 1 hypersensitivity releases

A

Vasoactive and spasmogenic subs which act on the vessels,smooth muscles and inflammatory cytokine recruit inflammatory cells

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4
Q

What are the phases of type 1 hypersensitivity

A

Immediate response= vasodilation, vascular leakage , smooth muscle spasm, glandular secretion—minutes after— VASODILATION, CONGESTION, EDEMA.

Late phase reaction= eosinophil, neutrophil, basophil, CD4+T cell infiltration, tissue destruction — 2 to 24 hours later— INFLAMMATORY INFILTRATE, RICH IN EOSINOPHILS, NEUTROPHILS and T CELLS

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5
Q

Which hypersensitivity type has high serum levels of IgE

A

Type 1

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6
Q

What is systemic anaphylaxis

A

Vascular shock
Widespread edema
Difficulty in breathing
Laryngeal edema
Vomiting
Abdominals cramps
Diarrhea
Laryngeal obstruction
Shock and die

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7
Q

Atopic allergy

A

Type 1
Urticaria
Angioedema
Allergic rhinitis hay fever
Bronchial asthma

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8
Q

What are the mechanisms of type 2 hypersensitivity

A

1-Opsonization and phagocytosis
2- Inflammation
3-Cellular Dysfunction

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9
Q

What is a Goodpasture syndrome

A

Type 2 hypersensitivity disease
Ab goes to kidney and lung basement membrane causing inflammation.
Nephritis and lung hemorrhages

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10
Q

Bulbous pemphigoid

A

Type 2 hypersensitivity disease
Vesicle formation in skin

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11
Q

Pernicious anemia

A

Type 2 hypersensitivity disease
Ab against the GIS
Megaloblastic anemia

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12
Q

Acute rheumatic fever

A

Type 2 hypersensitivity disease
Ab of streptococcal goes to heart muscle and cause distraction bc they lookalike
Carditis

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13
Q

Graves’ disease

A

Ab against the TSH receptor activate thyroid cells
Type 2 hypersensitivity disease

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14
Q

Myasthenia gravis

A

Ach receptor ab impair neuromuscular transmission
Type 2 hypersensitivity disease

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15
Q

Type 3 hypersensitivity

A

Mediated by antigen-antibody aggregates called ‘immune compexes’ which commonly occur in renal glomeruli,joint,skin,heart,serosal surface, small BV.
These complexes produce tissue damage mainly by inflammation.
Fever, urticaria,joint pain, vasculitis , glomerulonephritis, arthritis.
Acute necrotising vasculitis with necrosis of vessel wall and neutrophil is infiltration

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16
Q

Diseases that caused by type 3 hypersensitivity

A

Systemic lupus erythemotosis
Poststreptococcal GN
Polyarthritis Nodosa
Arthur’s reaction: localized tissue necrosis

17
Q

Which type of hypersensitivity disease doesn’t involve ab

A

Type 4

18
Q

Which type of hypersensitivity is mediated by T cells

A

Type 4

19
Q

How does type 4 hypersensitivity initiated

A

Ag activated T lymphocytes — delayed type hypersensitivity CD4+
— T cell mediated cytotoxicity CD8+

20
Q

What does CD4+ T cell mediated HS type 4 causes

A

Chronic inflammatory disease/autoimmune diseases)

21
Q

Which type of hypersensitivity reactions has a response to intracellular microbiologyical agents

A

Type 4

22
Q

What are the reactions of type 4 hypersensitivity

A

1- Proliferation and differentiation of CD4+ T cells= naive CD4 T cell recognize ag and differentiation of CD4+T cell to TH1,TH17 cell. Some of TH1, TH17 cells may remain in the memory pool of T cells

2- responses of differentiated effector T cells= repeat exposure to ag — memory T cell recognize ag and activated ,secrete cytokines ; TH1 activate macrophage, TH17 recruit neutrophils and monocytes

23
Q

Which type of hypersensitivity reactions is the major mechanism of defense against intracellular pathogens

A

Type 4 (mycobacteria, fungi, parasites, transplant rejection)

24
Q

Granuloma formation

A

Type 4 hypersensitivity
with persistent ag such as tbc colonizing lungs, peri vascular macrophage ,infiltration.
Activated macrophages cause morphological transformation into epi-like cells, epithelioid cells
Aggregation of cells surrounded by lymphocytes.

25
Q

Type 4 hypersensitivity diseases

A

Graft rejection
Viral disease
Type 1 DM
Multiple Sclerosis
Crohn Disease
Contact dermatitis
Rheumatoid arthritis

26
Q

Delayed type of type 4 hypersensitivity

A

Tuberculin reaction

27
Q

What happens in Cellular Dysfunction

A

Type 2
antireceptor ab impair or dysregulate normal function of receptors.Graves’ disease, myasthenia gravis

28
Q

Inflammation in type 2 hypersensitivity

A

Deposited ab activate complement, generating by product, causing recruit of neutrophils and release of enzymes
Glomerulonephritis
Vascular rejection

29
Q

Opsonization and phagocytosis

A

Type 2
Opsonization of cells by ab and complement components and ingestion by phagocytes
Transfusion reaction
Erytroblastosis fetalis
Autoimmune hemolytic anemia