Allergen IV
Type IV allergy in the Coombs and Gell classification is a cell-mediated delayed-type reaction. Sensitised T lymphocytes recognise the allergen and trigger an inflammatory skin response.
Triggers in gloves: not the base polymer but chemical residues from vulcanisation. The three relevant groups are thiurams (e.g. TMTD), dithiocarbamates (e.g. ZDBC) and benzothiazoles (e.g. MBT). Both latex and nitrile gloves are affected.
Clinical picture: eczematous contact dermatitis with erythema, itching, scaling and vesicles, confined to the contact area. Latency 12 to 48 hours after exposure.
Distinction from Type I allergy: that reaction is IgE-mediated, triggered by latex proteins, occurs within minutes and can progress to anaphylaxis. Type IV is more common; Type I is clinically more dangerous.
Diagnosis and prevention: patch testing; switching to accelerator-free gloves.
Frequently asked questions
What distinguishes Type IV from Type I allergy?
Type IV is T-cell-mediated, triggered by vulcanisation accelerators, and appears 12 to 48 hours after contact as eczema. Type I is IgE-mediated, triggered by latex proteins, occurs within minutes and can progress to anaphylaxis.
Which substances count as Allergen IV in gloves?
Chiefly vulcanisation accelerators: thiurams such as TMTD, dithiocarbamates such as ZDBC and benzothiazoles such as MBT. They occur in both latex and nitrile gloves; the base polymer itself is not the trigger.
How is a Type IV allergy diagnosed?
By patch testing with a dermatologist, using standard series containing rubber ingredients. Where sensitisation is confirmed, switching to accelerator-free gloves is the most effective measure.