· Intro
· Type 1 reaction
· Type 4 reaction
|
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 |