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 durin g the past 10 years, especially in many health care workers who have high e xposure to latex allergens both by direct skin contact and by inhalation of latex particles from powdered gloves. Development of satisfactory diagnost ic methods to verify the presence of latex allergy in health care workers r equires characterization of the immunoreactive proteins in latex products a nd identification of specific IgE antibodies in sensitized patients. A numb er of different latex preparations are now available for in vitro evaluatio ns. Objectives: Utilizing different in vitro methods, this study examines IgE s ensitization to components of latex in a selected population of hospital em ployees, employing a raw natural latex glove extract and Various commercial latex extracts. Methods: Two hundred hospital employees exposed to latex were evaluated usi ng an allergy history questionnaire. To further identify sensitized patient s, two different specific IgE tests and leukocyte histamine release tests w ere performed using a panel of latex extracts obtained from different manuf acturers. Sodium dodecylsulfate polyacrylamide electrophoresis (SDS-PAGE) p rofiles were obtained. Sera from 34 subjects suspected to be latex-sensitiz ed 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 t ests (18 individuals) and/or positive histamine release tests (26 individua ls). Significant extract differences in both the histamine release response profile and the frequency of positive test results were noted in the hista mine release test. Significant individual differences in patients' latex ep itope-specificity were found by IgE immunoblotting, substantiated by sodium dodecylsulfate polyacrylamide profiles revealing differences in protein ba nd 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 s ubjects (22%) of the 34 considered to be latex-sensitized did not reveal bi nding of specific IgE in immunoblots. One latex extract (Stallergene) with the widest IgE-reacting protein repertoire identified the majority of subje cts (63%) as latex sensitive by leukocyte histamine release and also provid ed the best quantitative histamine release test results. Conclusion: Only by testing with a combination of latex extracts were all s ensitized individuals identified. This study demonstrates that currently se veral in vitro methods may be necessary to detect IgE sensitization to late x. Latex extracts to be employed in future skin tests must contain a wide e pitope repertoire of IgE-binding proteins to identify all latex-sensitized individuals.