What is a Type 1 Reaction to Latex?
Currently, 14 allergens have been identified named by the abbreviation Hev b “n”. Allergens sensitize individuals through different routes establishing different risk groups. Major allergens in patients with spina bifida and multiple operations are Hev b1 and 3, and in healthcare professionals, Hev b 5 and 6.
Reactions Associated with Latex: Sensitization is the process by which anti-latex specific IgE is generated, without clinical manifestations. In fact, sensitization does not necessarily mean clinical allergy. Clinical symptoms are produced by mechanisms of immediate hypersensitivity (IgE, type 1) and delayed hypersensitivity (type 4).
Clinical manifestations due to hypersensitivity type I to latex proteins vary widely and depend on the route of exposure, the amount of allergen and individual factors:
-Contact Urticaria: It is the most frequent manifestation and the most common cause of urticaria of occupational contact, which may be unique or precede systemic reactions. Pruritus, xeroderma and eczema are nonspecific manifestations.
-Rhinitis and Allergic Asthma: They affect mainly health professionals and workers exposed to latex in their work environment. The main source is powdered gloves. It is a cause of occupational asthma.
-Systemic Reactions: Latex is the second cause, after muscle relaxants, of intraoperative anaphylaxis, and occurs more commonly during the maintenance phase of anesthesia as a cardiogenic shock. Abdominal, gynecological and traumatological interventions are the ones with the greatest risk.
-Latex-fruit Syndrome: The latex-fruit association is variable, with a high asymptomatic sensitivity index. It is due to cross-reactivity mediated mainly by Hev b 6. The most frequently related foods are banana, kiwi, chestnut and avocado. The clinical presentation varies widely, and can be presented as anaphylaxis (acute allergic reaction) in up to 50% of cases.
-Clinical Presentation in Spina Bifida: These children are sensitized by several routes, including the mucosa, and its most frequent manifestation is urticaria-angioedema.
Type 1 Hypersensitivity Reaction
It is the most serious and can be associated with considerable morbidity and mortality. It depends on the production of specific IgE against Hev b, sensitization of mast cells and degranulation before a second exposure. Clinically it can be manifested by urticaria and even by anaphylaxis.
Latex proteins are absorbed slowly when they are in the air and symptoms usually appear about 30 minutes after exposure. Mild reactions include urticaria, rhinitis and conjunctivitis and are usually caused by exposure through inhalation or by direct contact with the skin. Severe reactions usually occur soon after parenteral or mucosal exposure. A recent study of anaphylaxis during anesthesia showed that cardiovascular symptoms (73.6%), cutaneous manifestations (69.6%) and bronchospasm (44.2%) are the most frequent findings. However, in anaphylaxis during anesthesia other possible causes should be considered, including propofol, muscle relaxants and opioids.
Workers in the health area, other workers exposed to latex, patients with atopic features and children with spina bifida or genitourinary anomalies subjected to multiple surgeries represent the main groups at risk of presenting latex allergy. Hev b 1 is the most important allergen in the sensitization of infants with spina bifida. The prevalence of latex sensitization in the non-atopic general population is less than 1% while it is 3% to 12% in health workers. Although sensitization does not always progress to the appearance of symptoms, continued exposure may predispose to symptoms. In contrast, age, race and sex do not influence latex allergy.
In recent years the use of latex gloves in developed countries has been greatly reduced. At the same time, sensitivity and symptoms related to latex exposure – allergy, pruritus, asthma and rhinoconjunctivitis – also appear to have declined in association with the increased use of gloves with low protein content and no dust.
Type I hypersensitivity reaction, mediated by IgE is the most serious reaction. It requires sensitization and the production of specific IgE. During the initial exposure, the individual is sensitized with the generation of specific IgE against Hev b. The released mediators such as histamine, proteases, metabolites of arachidonic acid (leukotrienes and prostaglandins) leads to reactions that fluctuate in intensity between urticaria and anaphylaxis.
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