Inhalation challenge testing of latex-sensitive health care workers and the effectiveness of laminar flow HEPA–filtered helmets in reducing rhinoconjunctival and asthmatic reactions☆,☆☆,★,★★

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Abstract

Background: There are few data relating latex aeroallergen concentrations to biologic responses in latex-sensitized persons. Objectives: We sought to investigate acceptable latex aeroallergen concentrations below which latex-sensitive health care workers do not experience symptoms and to study the effect of high-efficiency particle arrest (HEPA)–filtered laminar flow helmets in preventing latex-induced symptoms. Methods: Under challenge chamber conditions, latex-sensitive health care workers underwent 7 sequential inhalation challenge tests by donning and discarding either vinyl gloves (challenge 1), low latex–allergen powder-free gloves (challenge 2), or high latex–allergen powdered gloves (challenges 3 to 7) for up to 1 hour. Volunteers wore a laminar flow helmet during all challenges; HEPA filters in the helmet were in place only during challenges 3 and 4. Flow-volume loops, symptom scores, and latex aeroallergen concentrations were measured before and during each test. Results: At 60 minutes, latex aeroallergen concentrations during challenges 3 to 7 (mean, 7600 ng/m3 ; range, 93 to 54,000 ng/m3 ) were significantly higher than during challenges 1 or 2 (mean, 65 ng/m3 ; range, nondetectable to 100 ng/m3 ) (P < .001). During challenges 5 and 6, mean maximum percent falls in FEV1 (–16% and –11%, respectively) were significantly greater compared with those measured during challenges 3 and 4 (–3% and –1%, respectively) (P = .03). Mean maximum change from baseline symptom scores during challenges 5 and 6 was significantly higher than that during challenges 3 and 4 (P = .006). During challenges with high latex–allergen gloves, 4 volunteers had reproducible FEV1 falls of 20% or greater at cumulative inhaled latex aeroallergen doses ranging from less than 100 ng to 1500 ng. Conclusion: The laminar flow helmets were effective in reducing latex-induced symptoms. Only 1 volunteer exhibited a fall in FEV1 of 20% or greater after a cumulative inhaled latex aeroallergen dose of less than 100 ng, and no volunteer showed a decline in FEV1 after exposure to powder-free low allergen gloves. (J Allergy Clin Immunol 1998;102:998-1004.)

Section snippets

Subjects

We recruited 11 nonsmoking Mayo Medical Center female employees with clinical histories of occupational asthma (cough, wheeze, and/or shortness of breath) after latex exposure, all of whom had previously documented positive puncture skin test responses to NRL, elevated latex-specific serum IgE antibodies, or both (Table I).

. Study group characteristics

Volunteer noAge (y)Work locationAtopicPuncture skin test (mm wheal diameter)
HistamineLatex
1 mg/mL0.25 mg/mL2.5 mg/mL
135Allergy/immunization Clinic

Safety

Eight volunteers completed all 7 challenge tests. A ninth volunteer completed 6 challenge tests, and the other 2 volunteers withdrew from the study after the second and third challenge tests (1 because of a family emergency and 1 fearing more severe reactions with future challenges). Data from the latter 2 subjects were excluded from all analyses. One volunteer (number 4), who had moderate positive latex skin test responses 6 years previously, now showed only a minimal positive skin test

DISCUSSION

On the basis of feedback provided by our institutional review board, the experimental design of our pilot study was chosen to maximize safety to the participants. Thus the order of testing the gloves was not randomized, and each subject was exposed to lower aeroallergen doses first (helmet filters in place) and higher aeroallergen doses later (helmet filters removed). Also, because the challenge chamber had not been used for previous studies, it was necessary to document the reproducibility of

Acknowledgements

We thank Dr Kenneth C. Beck and Mr Mike Witzke of the Mayo Pulmonary Function Laboratory for their expert assistance and advice in setting up the pulmonary function testing equipment and protocol and Drs Charles E. Reed and Loren W. Hunt for helpful discussions. We also thank Ms Kathy Mieras and Ms Sue Thisius for performing the pulmonary function tests and Ms Marian Bortolon for her secretarial assistance.

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From a the Mayo Graduate School of Medicine, b the Department of Pediatric and Adolescent Medicine, c the Section of Biostatistics, Department of Health Sciences Research, and d the Allergic Diseases Research Laboratory, Mayo Clinic and Foundation, Rochester.

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Supported in part by Safeskin Corporation and the Mayo Foundation.

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Reprint requests: John W. Yunginger, MD, Allergic Diseases Research Laboratory, 406 Guggenheim Building, Mayo Clinic, 200 First Street SW, Rochester, MN 55905.

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