Hypersensitivity

Question 1

What are the symptoms of hypersensitivity reaction ?

Answer 1

Itchying ,pain ,burning ,flacking and ooozing

Question 2

List the components of the type 1 reaction (1,2,3,4,5)

Answer 2

Type 1 reaction ; T helper cell type 2 ;IL3 ,Il4 and IL5 which is also used to recruite Eosinphils

Question 3

Discuss the causes, Investigations of Urticaria and state which type of immune response it is?

Answer 3

1. Type 1 immune response
2. Causes : food ,drugs ,insect bite ,blood and serum ,infection
   3.Investigations
   *Diagnoses of Urticaria and angioedema is clinical
   *Skin biopsy(if lesion lasts for >24 hours )
   *skin prick test /Rast (radioallergosorbent test )
   > for chronic cases (>/= 6 weeks ): FBC ,Anti nuclear antibody ,hepatitis and HIV serology

Question 4

Treatment for type 1 hypersensitivity?

Answer 4

Severe cases: Adrenaline
mild cases: antihistamine
Refractory cases: prednisone

Question 5

Discuss the pathology of type 2 ( cytotoxic ) hypersensitivity?

Answer 5

An antigen on cell membrane or tissue ,AB binds to the antigen. damages cells directly or via complete or killer cell effect

Question 6

Discuss the Pemphigus presentation and diagnosis

Answer 6

Pemphigus is an autoimmune blistering skin disease.
Presentation: oral ulcers, blisters and erosions of the skin and it is common in adults . Lesions start in the mouth then follow on the body. Chicken wire appearance of epidermis on immunofluorescence test on skin biopsy
>Type 2 hypersensitivity reaction

Question 7

Discuss the Pemphigoid presentation, cause, diagnosis and investigation

Answer 7

Pemphigoid presents as bullae ,erythema patches and erosions on the skin .

Diagnosis : Positive direct immunoflurescence test on the skin biospy with linear IgG bands on basement membrane. AB against component membrane.

Investigation : Skin biopsy ,immunoflurescence test on skin

Question 8

Treatment for type 2 hypersensitivity reaction

Answer 8

Prednisone ; Cyclosporine ;Cyclophosphamide ;high dose IG IV ,dapsone

Question 9

Discuss type 3 (immune complex ) pathology

Answer 9

Circulating immune complexes IgG stick to venules causing areas of stasis for example legs. Mast cells and neutrophils are attracted and the complement is activated resulting in damage of the vessels: Vasculitis

Question 10

Discuss the leukocytoclastic vasculitis presentation ,causes ,investiagtion and treatment

Answer 10

Presents as palpable purpura , haemorrhagic blisters and ulcers. Fever, arthritis and systemic involvement: Nephiritis, GIt bleeding ,and uvetis

Causes : Infection (strept,E coli ) ,drugs (NSAID ,antibiotics ) ,malignancy ect

Treatment: bed rest , antihistamine, dapsone , prednisone, and colchicine

Investigations: Skin biopsy, immunofluorescence, FBC , urinalysis, and stool for occult blood

Question 11

Discuss Allergic contact dermatitis causes; investigation and treatment

Answer 11

Presentation: well-demarcated erythematous scaly plaque.Affects specific individuals on contact with antigens

Causes : nickel ,AB ,cement ,fragrance

Investigation: Patch test (clinically suspected chemicals in decreased concentration is applied on back and removed 3 days after

Treatment: Topical steriod eg clobestasol

Question 12

Give a prototype disease with a mixed mechanism :

Answer 12

Atopic dermatitis

Question 13

Discuss the presentation ,MOA ,cause and treatment of atopic dermatitis

Answer 13

Presents as a dry itchy ,sensitive irritable skin

• Can have acute ,subacute and chronic stages
• MOA : Type 1 and 4 mechanism
• Cause : no specific cause ,it occurs in hayfever ,food and allergies
• Treatment : Topical steriods , AB if infected ,antihistamine but has a minimum role