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Natural rubber latex is intracellular cytosol secreted from rubber tree, Hevea brasiliensis (Hev b). Due to its excellent elastic properties it is widely used in medical devices and everyday products.
Latex allergy was first diagnosed in 1927, in Germany. People at risk of latex allergies due to exposure include:
- Healthcare workers
- Hospital theatre staff
- Patients needing recurrent surgeries
- Hairdressers
- Cleaning staff.
There is a prevalence of latex allergy in 4% of the public. The allergy is mostly an immediate IgE-mediated allergic response. Type IV allergic reactions cause skin reactions 24-48 hours after exposure. Currently, 15 allergens have been characterised and listed by the World Health Organization, causing:
- Skin rash
- Urticaria
- Angio-oedema
- Rhinitis
- Wheezing
- Conjunctivitis
- Systemic:
- Cardiovascular collapse
- Anaphylaxis – often intraoperative.
The route of sensitisation is mostly airborne allergens. Corn starch is used in powered latex gloves, which creates latex protein aerosolisation. Power-free glove usage prevented the future increase in prevalence in the 1990s.
Diagnosis is based on history, atopy, other atopic manifestations, other sensitisations and occupation exposure. It is done through careful interpretation and allergy testing
To treat latex allergy, the following is used:
- Avoidance
- Treat other allergic conditions including asthma well
- Antihistamines (second generation)
- EpiPen/ adrenalin
- Medic Alert bracelet
- Specific immunotherapy.
Latex fruit syndrome
In infants and young children, food allergy usually precedes aeroallergen hypersensitivity (primary sensitisation to ingested antigens). The opposite is frequently observed in adults.
Panallergens provide common epitopes for IgE antibodies to bind to. In pollen-food syndrome, the Birch tree in Europe and the most common elicitor of allergies. There is cross-reaction with several foods. Apple, kiwi, peach, pear, apricot, cherry, strawberry, and hazel nuts are most affected. Allergies are mostly seen in those with food allergies related to birch pollen sensitisation.
Latex-fruit syndrome was first described in a latex-allergic patient in 1991. It is found in avocado, banana, kiwifruit and papaya, among others. In 1994, Blanco et al found that 50% of latex-allergic patients had hypersensitivity to fruits.
Avocado allergy
The main allergen found in avocado is called Pers a 1. This is a chitinase, which is a plant-derived enzyme made by plants naturally to act as a defence against fungal attacks.
In a study, Pers a 1 induced positive skin reactivity responses in seven of eight patients with latex-fruit allergy and in another study, it was recognised by 15 out of 20 avocado- and/or latex-allergic patients.
Component testing
Differentiate between the primary and cross-reactive allergy. Latex positivity (k82) can also be explained by IgE antibodies against cross-reactive carbohydrate determinants (CCDs) and can be detected with MUFX3.
Comprehensive sensitisation profiling helps differentiate between primary and cross-sensitivity allergy.
Latex allergen components and cross-reactivity
The rule in primary allergy with allergen components is: Rule out primary allergy with cross-reactive components.
Latex sensitisation can also be explained by CCDs (MUFX3).
Test using the algorithm for suspected latex allergy: ImmunoCAP whole allergen and ImmunoCAP allergen components.
