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

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 biters 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/m(3); range, 93 to 54,000 ng/m3) were significantly higher than during challenges 1 or 2 (mean, 65 ng/m(3); range, nondetectable to 100 ng/m(3)) (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.