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The Pathophysiology of Latex Allergy

- all the Immunology you need to know

• An allergic reaction is one mediated by immunologic mechanisms i.e. the interaction of a foreign molecule, or antigen, with host antibodies and/or effector cells.

   

• A life-threatening allergic reaction mediated by antibodies is known as anaphylactic. When antibodies are not responsible for the reaction, it is termed anaphylactoid and may involve complement activation or non-immunologic release of histamine.

   

• Anaphylactic and anaphylactoid reactions cannot be distinguished by clinical observation.

   

• Antigen binding to IgE antibodies initiates anaphylaxis. Prior exposure to the antigen, or a substance of a similar structure is required to produce sensitisation. On re-exposure, binding of the antigen bridges to immunospecific IgE antibodies located on the surfaces of mast cells and basophils, liberating histamine and other inflammatory mediators, such as leukotrienes, prostaglandins and kinins. The liberated mediators produce a respiratory, cardiovascular and cutaneous symptom complex. See Diagnosis of Anaphylaxis.

   

• Intra-operative latex anaphylaxis is immunologic and mediated by IgE

 
• Latex can also result in reactions that are limited to the skin. This type of allergy is not IgE-related and is classified immunologically as a Type IV reaction (anaphylaxis is Type I). Clinically this is seen as rubber glove eczema in health care workers, contact stomatitis in those using rubber orthodontic appliances, and condom dermatitis. These reactions are not life-threatening, are unrelated to the proteins that incite Type I reactions and are probably due to chemicals (mercaptothiobenzothiazole, tetramethyliuram) added to rubber during processing.

   

• Type IV reactions (contact dermatitis) occur mostly in patients with occupational exposure to latex. But note that contact dermatits, especially in atopic individuals, may portend future systemic (Type I - anaphylactic) sensitivity.