2000B15 Write brief notes on latex allergy.

Definition

·   Hypersensitivity to latex a natural derivative of the rubber tree

Risk factors

·   Atopy (asthma, eczema, allergic rhinitis)

·   Frequent exposure (i.e. health care workers)

Severity

·   Varies from mild to life-threatening

Source

·   Hospitals: disposable gloves, urine catheters, anaesthetic tubing

·   Anywhere: rubber bands, shoes

·   Cross-sensitivity: banana, kiwifruit, avocado

Implication

·   Minimise exposure: stock latex-only gloves and other products

Characteristics

·   All-or-nothing

·   Immediate

·   Life-threatening

Aetiology

·   First exposure -> sensitization (10-14 days)

o Antigen presenting cell engulfs antigen, presents on MHC-II

o APC activates specific T cell

o T cell activates specific B cell

o B cell produces specific IgE

o IgE fixes to mast cells and basophils

o 10-14 day process

·   Second exposure -> systemic degranulation (seconds)

Pathophysiology

·   Early mediators: histamine, serotonin, tryptase

·   Late mediators: leukotrienes, prostaglandins, bradykinin, platelet factor 4

·   Vasodilation, capillary leak

·   Angioedema, upper airway obstruction

·   Hypotension, arrest

·   Bronchospasm

Treatment

·   Adrenaline

o α₁: vasoconstriction -> ↑SVR -> ↑mAP

o β₁: ↑heart rate, contractility -> ↑mAP

o β₂: bronchodilatation, stabilize mast cells

·   Glucocorticoid:

o ↓Late mediator production

o Antihistamine

o ↓Vasodilation, capillary leak

Test

·   Prick skin ->apply latex solution -> observe for weal and flare

·   Radioallergosorbent assay

·   Serial tryptase (+1h, +6h)

Key features

·   Slower

·   Generally less severe

Aetiology / pathophysiology

·   Antigen presented to T lymphocyte

·   Cytokine release

·   Local activation of macrophages

·   Well demarcated erythematous urticarial rash

Test

·   Apply skin patch with antigen for 24 hours -> observe for reaction