In vitro diagnosis of chronic nasal inflammation

Background Differential diagnosis of chronic nasal inflammation is insufficient when based solely on clinical examination and radiography of paranasal sinuses. Patients complain about more or less similar symptoms. Activation of mast cells and eosinophils is pivotal in nasal inflammation. Objective To compare tryptase and eosinophilic cationic protein (ECP) in nasal secretions in different forms of chronic nasal inflammation and to establish norm values. Methods The study included 1710 patients presenting with nasal complaints. Nasal secretions were gained by the cotton wool method and analysed for tryptase, as a marker of mast cell activation, and for ECP, as a marker of tissue eosinophilia and activation. Patients were grouped according to their diagnosis: chronic, non-allergic rhinosinusitis (sinusitis, n = 194), non-allergic nasal polyposis (polyposis, n = 138), non-allergic rhinitis with eosinophilia syndrome (NARES, n = 198), isolated perennial allergic rhinitis (AR) (n = 126), isolated seasonal AR (n = 132), and patients allergic to both, seasonal and perennial allergens (n = 193). Seven hundred and twenty-nine patients with nasal complaints due to a deviated septum and without any nasal inflammation served as controls. Results Nasal tryptase was highly significantly (P < 0.001) elevated in polyposis, NARES, and in AR. ECP was highly significantly (P < 0.001) elevated in all groups of patients suffering from chronic nasal inflammation. Based on our data and method we established norm values (95% confidence interval of mean value) for nasal tryptase in healthy adults, ranging from 12.0 to 18.7 ng/mL and for ECP ranging from 84.4 to 102.6 ng/mL. Conclusion Mast cells and eosinophils are involved in non-allergic and allergic forms of chronic nasal inflammation. We established an in vitro assay for tryptase and ECP in nasal secretions and defined norm values based on our data and method. In vitro measurement of biological markers in nasal secretions provides important information for differential diagnosis and therapeutic strategies of chronic nasal inflammation.