Assessment of IgE allergen specificity among latex-allergic health care workers: review of IgE-binding components of various latex extracts.

Background: Allergic reactions to natural rubber latex have increased during the past 10 years, especially in many health care workers who have high exposure to latex allergens both by direct skin contact and by inhalation of latex particles from powdered gloves. Development of satisfactory diagnostic methods to verify the presence of latex allergy in health care workers requires characterization of the immunoreactive proteins in latex products and identification of specific IgE antibodies in sensitized patients. A number of different latex preparations are now available for in vitro evaluations.

Objectives: Utilizing different in vitro methods, this study examines IgE sensitization to components of latex in a selected population of hospital employees, employing a raw natural latex glove extract and various commercial latex extracts.

Methods: Two hundred hospital employees exposed to latex were evaluated using an allergy history questionnaire. To further identify sensitized patients, two different specific IgE tests and leukocyte histamine release tests were performed using a panel of latex extracts obtained from different manufacturers. Sodium dodecylsulfate polyacrylamide electrophoresis (SDS-PAGE) profiles were obtained. Sera from 34 subjects suspected to be latex-sensitized were IgE immunoblotted to assess the presence of IgE antibodies directed toward specific latex proteins.

Results: Thirty-four participants (17%) were considered sensitized to latex by a positive clinical history in conjunction with positive specific IgE tests (18 individuals) and/or positive histamine release tests (26 individuals). Significant extract differences in both the histamine release response profile and the frequency of positive test results were noted in the histamine release test. Significant individual differences in patients' latex epitope-specificity were found by IgE immunoblotting, substantiated by sodium dodecylsulfate polyacrylamide profiles revealing differences in protein band patterns among the various extracts. The IgE immunoblots indicated that the majority of patients reacted to proteins with molecular weights of 14, 21, 30 to 35, and 42 kD; the 30 to 35 kD protein being predominant. Seven subjects (22%) of the 34 considered to be latex-sensitized did not reveal binding of specific IgE in immunoblots. One latex extract (Stallergene) with the widest IgE-reacting protein repertoire identified the majority of subjects (63%) as latex sensitive by leukocyte histamine release and also provided the best quantitative histamine release test results.

Conclusion: Only by testing with a combination of latex extracts were all sensitized individuals identified. This study demonstrates that currently several in vitro methods may be necessary to detect IgE sensitization to latex. Latex extracts to be employed in future skin tests must contain a wide epitope repertoire of IgE-binding proteins to identify all latex-sensitized individuals.