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PHM 603- Immunology > Type IV Hypersensitivity > Flashcards

Type IV Hypersensitivity Flashcards

1
Q

What type of hypersensitivity is Type IV hypersensitivity?

A

Cell-mediated

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2
Q

Are antibodies involved in type IV hypersensitivity?

A

No

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3
Q

Types of Type IV hypersensitivity

A

Delayed-type, cytotoxic cell-mediated

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4
Q

What happens in delayed hypersensitivity?

A

Upon initial exposure to the antigen, the person’s body formed B memory cells with sensitized lymphocytes and facilitated by T-helper cells.

Cell death results from cytotoxic T-lymphocytes, associated cytokines, and recruitment of macrophages

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5
Q

Chronic and acute diseases manifested by cell-mediated hypersensitivity

A

TB, leprosy, schistosomiasis, contact dermatitis, eczema, SJS, TEN, SJS/TEN, AGEP

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6
Q

What kind of hypersensitivity is contact dermatitis? (Specific subset of Type IV)

A

IVa, IVc

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7
Q

Causes of contact dermatitis

A

Cosmetics, drugs, clothes dye, food, rubber, latex, poison ivy/mango leaves

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8
Q

Signs/Sx of contact dermatitis

A

Burning or stinging with erythema, swelling, peeling, blisters with oozing and crusting, possibly severe itching

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9
Q

Time of onset of contact dermatitis symptoms

A

Within a few hours of exposure

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10
Q

Contact dermatitis treatment

A

Topical steroids, antihistamines, topical immunomodulators (topical calcineurin inhibitors), systemic steroids, cold compresses, calamine lotion, oatmeal baths, mild soaps, non-irritating moisturizers, non-scented detergents, avoid known triggers, wash skin after exposure

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11
Q

What kind of hypersensitivity is SJS, TEN, SJS/TEN? (Specific subtype of Type IV)

A

Type IVc

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12
Q

Body distribution of SJS

A

<10% of BSA

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13
Q

Body distribution of TEN

A

> 30% of BSA

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14
Q

Body distribution of SJS/TEN

A

15-30% of BSA

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15
Q

Clinical presentation of SJS, TEN, SJS/TEN

A

Macules that rapidly spread and coalesce, leading to epidermal blistering, necrosis, and sloughing

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16
Q

Symptoms of SJS, TEN, SJS/TEN

A

Sore throat, fever, fatigue, burning eyes for 1-3 days; tingling/burning of skin early on, ulcers and other lesions appear in mucous membranes, conjunctivitis, rash of lesions on the face, arms, trunk, legs, soles -> blisters develop and erosion of confluent macules

17
Q

Populations at risk of SJS, TEN, SJS/TEN

A

Bone marrow transplant patients, Pneumocystis jirovecii-infected HIV patients, patients with SLE, patients with chronic rheumatologic diseases, middle-aged and older women

18
Q

Pharmacologic causes of SJS, TEN, SJS/TEN

A

Sulfa drugs, ABX (aminopenicillins like ampicillin, amoxicillin, fluoroquinolones, cephalosporins), antiepileptics, piroxicam, allopurinol

19
Q

Non-pharmacologic causes of SJS, TEN, SJS/TEN

A

Infection, viral, vaccination, graft vs. host disease

20
Q

Treatment of SJS, TEN, SJS/TEN

A

Stop offending agent, wound care, eye care, pain management, fluid, electrolyte, nutrition management, cyclosporine and etanercept

21
Q

What kind of hypersensitivity is AGEP? (Specific subset)

A

Type IVd

22
Q

Clinical presentation of AGEP

A

Rapid appearance of hundreds to thousands of small, non-follicular subepidermal and intradermal sterile pustules with a background of erythema

23
Q

Onset of AGEP

A

Up to 3 weeks after drug exposure

24
Q

Drugs that cause AGEP

A

Aminopenicillins, sulfonamides, quinolones, hydroxychloroquine, terbinafine, diltiazem

25
Q

AGEP Treatment

A

Stop offending agent, fluid, electrolyte, nutrition management, topical corticosteroids, PO antihistamines, analgesics

26
Q

What kind of type IV hypersensitivity is a TB test?

A

IVa

27
Q

TB test looks to see…

A

…whether or not a patient has had prior exposure to TB (having the virus or getting the live attenuated vaccine for it)

28
Q

TB test

A

Intradermal injection of TST in the upper arm, observe 48-72 hours later.

29
Q

A positive TB test is…

A

…a wheal and flare response of >5mm

30
Q

Anergy definition

A

Absence of a cell-mediated immune response

31
Q

Anergy is what type of hypersensitivity reaction?

A

Type IV

32
Q

A false negative to a TB test may result in these patients with anergy…

A

Elderly, severely debilitated, disseminated TB, HIV, patients taking immunosuppressive treatment, glucocorticoid therapy, patients who had a recent viral infection

33
Q

What happens if anergy is suspected?

A

Use control skin tests of candida or mumps; if one of the controls is positive but the TB one is still negative then they didn’t have prior exposure to TB

PHM 603- Immunology (21 decks)

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