IgE-mediated allergic reactions to protein allergens in natural rubber latex derived from the Hevea brasiliensis tree emerged in the 1990s as a concern with occasional allergic manifestations. Symptoms encompassing hives, uriticaria, rhinitis, asthma and anaphylaxis have all been reported in latex allergic individuals exposed to products derived from natural rubber latex.
Since no safe level of Hevea latex allergen exposure is known, avoidance is the primary mode of treating latex allergy.
As a result of investigations conducted by many scientists across the world, thirteen latex allergens have so far been identified and categorized by the Allergen Nomenclature Sub-Committee of the International Union of Immunological Societies (IUIS) as Hev b 1 to Hev b 13 (Table 1) (see Specification D 1193
From the historical context, a number of assays have been developed to quantify the level of protein, antigen and allergen in natural rubber latex containing products (see Practices D 4483
The modified Lowry assay for total protein, Test Method D 5712
The second assay to be developed involved the use of human latex-specific IgE antibody in a competitive inhibition immunoassay format to estimate the overall allergenic potency of a natural rubber product extract (5, 6). The extract is incubated with human serum containing latex-specific IgE antibody and then this mixture is incubated with a solid phase latex allergosorbent. Latex allergenic proteins, if they are present, bind to the latex-specific IgE antibody in solution and they thus inhibit IgE antibody binding onto the latex allergosorbent. Allergosorbent bound IgE is then quantified and the extent of competitive inhibition of IgE binding is a measure of latex allergens. While this assay provides an estimate of the allergenicity or level of natural rubber allergens extractable from a product, difficulty in procuring reproducible lots of latex specific IgE containing human serum has precluded widespread use of this assay. For this reason, this assay has not been put forth as an ASTM standard.
A third assay design is similar to the human IgE based competitive inhibition immunoassay, but it employs rabbit antiserum instead of human serum containing IgE anti-latex. The
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