Role of skin prick test and serological measurement of specific IgE in the diagnosis of occupational asthma resulting from exposure to vinyl sulphone reactive dyes

Abstract

Objectives-Some patients with occupational asthma resulting from exposure to reactive dyes have skin reactivity to the causative dyes and specific IgE to reactive dyes have been found in these patients. However, the usefulness of skin prick tests (SPTs) and serological measurement of specific IgE in screening, diagnosis, and monitoring the occupational asthma resulting from exposure to reactive dyes have not yet been assessed. In this study, the clinical validation of SPTs and measurement of specific IgE to vinyl sulphone reactive dyes by enzyme linked immunosorbent assay (ELISA) was evaluated. Methods-42 Patients with occupational asthma from reactive dyes (true positive group) were enrolled. In these the causative reactive dye was confirmed by bronchial challenge test. 93 Asymptomatic factory workers with negative challenge to the reactive dye (true negative group) and 16 unexposed controls with negative challenge to the reactive dye were also enrolled. Skin prick tests were done with 10 mg/ml reactive dye in 0.4% phenol/0.9% saline. IgE specific to reactive dye conjugated to human serum albumin (HSA) was measured with enzyme linked immunosorbent assays (ELISAs). Results-None of the unexposed controls had a positive response to SPTs. The sensitivity (76.2% v 53.7%), specificity (91.4% v 86.0%), positive predictive value (80.0% v 62.9%), and negative predictive value (89.5% v 80.8%) of SPTs were higher than those of ELISAs. The mean weal size of reaction to reactive dye was weakly correlated with the ELISA optical density of IgE to reactive dye conjugate in patients with occupational asthma from reactive dyes (n=41, r=0.337, p<0.05). In four patients with occupational asthma from reactive dyes and eight control subjects exposed to reactive dye, IgE specific to reactive dye conjugated to HSA was detected with ELISA even though they showed negative skin reactivity. Six patients completely avoided the reactive dye for a mean (SD) 27.8 (10.3) months, IgE specific to reactive dyes decreased in all six patients (p<0.05) during this time.Conclusions-Both SPTs and detection of IgE specific to reactive dye in serum samples could be valuable for screening, diagnosis, and monitoring occupational asthma resulting from exposure to reactive dyes. These two tests would complement each other. (Occup Environ Med 2001;58:411-416)

Comparison of Skin Prick Tests with In Vitro Allergy Tests in the Characterization of Horses with Recurrent Airway Obstruction

“…SPT showed higher sensitivity, specificity, PPV, and NPV than both ELISA tests, similar to the results found by Park et al [37] in humans. In human medicine, SPTs are considered the gold standard of allergy tests.…”

Guidelines for the management of work-related asthma

“…7) Both skin-prick and specific IgE measurement are sensitive for detecting type 1 sensitization and occupational asthma caused by acid anhydrides and some reactive dyes, but have a lower specificity for diagnosing occupational asthma (**) [58][59][60][61].…”

Skin prick tests and allergy diagnosis

“…SPT is useful to confi rm or exclude a suspected diagnosis of allergic rhinitis, allergic conjunctivitis or asthma triggered by allergens 10,20,21 and to demonstrate sensitisation to inhalant occupational allergens. 22,23 Previous observations suggest that skin test positivity at an early age is associated with subsequent development of rhinitis and wheeze. [24][25][26] The role of allergic sensitisation as a cause of eczema is less clear.…”