Objective: Measurement of total immunoglobulin E (IgE) is clinically important for the diagnosis of allergic diseases. The total serum IgE level is normally measured because of its widespread use and convenience, but little attention has been paid to the measurement of local IgE concentrations. We evaluated whether the measurement of local production of IgE in tears, saliva, and nasal mucus was useful for the diagnosis of allergic rhinoconjunctivitis.
Methods: A prospective, nonrandomized, cross-sectional study was conducted in 33 consecutive patients with seasonal allergic rhinoconjunctivitis (allergic group) and in 30 age- and sex-matched healthy control subjects (control group). The total IgE level was measured in tears, saliva, and nasal mucus from all subjects. Using a 4- or 5-point scale, symptoms (sneezing, rhinorrhea, nasal obstruction, ocular itching, and lacrimation) were assessed in each subject along with the activities of daily living (ADL) score and total symptom score for allergic conjunctivitis.
Results: Total IgE could be assayed within 10 minutes of collection in all samples. The scores for all symptoms were higher in the allergic group than in the control group (p < .00001). The IgE scores for tear fluid samples (p < .00001) and undiluted saliva (p = .00003) were significantly higher in the allergic group than in the control group. The total IgE score of tear fluid samples was strongly correlated with the severity of symptoms of allergic conjunctivitis, including ocular itching (r = 0.769, p < .00001), tearing (r = 0.560, p = .00035), and ocular symptom score (r = 0.329, p = .03452). On the contrary, the total IgE scores for both saliva and nasal mucus were correlated with the severity of rhinitis-related symptoms, including sneezing (saliva r = 0.897, p < .00001; nasal mucus r = 0.871, p = .00024), nose blowing (saliva r = 0.764, p < .00001; nasal mucus r = 0.829, p = .00080), and nasal obstruction (saliva r = 0.519, p = .00099; nasal mucus r = 0.745, p = .00429). The ADL score was correlated with the total IgE level in each specimen (tear r = 0.705, p < .00001; saliva r = 0.468, p = .00301; nasal mucus r = 0.479, p = .06816).
Conclusions: These results suggest that local production of IgE is closely correlated with local allergic symptoms. This rapid test for the measurement of local IgE is easy to perform on an outpatient basis and may be helpful in the diagnosis of allergic rhinitis and conjunctivitis.