Increased expression of ICAM-1 has been demonstrated on conjunctival and nasal epithelium in patients with asymptomatic allergic rhinitis caused by mites. This study demonstrated that symptom-free patients sensitized and exposed to perennial allergens always have a weak ICAM-1 expression, even when they are symptom free; this is known as the concept of minimal persistent inflammation, which is also present in patients with seasonal allergic rhinitis. A study in allergic patients has shown that ICAM-1 expression on conjunctival epithelium derives from endogenous synthesis. As inflammation determines prognosis in asthma, there is a need to measure it. Bronchial biopsy remains the standard by which to determine inflammation in the airways.”
However, the process is invasive and unsuitable for repeated use. Therefore, noninvasive methods based on the study of the cellular and soluble mediator content of induced sputum, exhaled constituents of breath, and circulating activation markers of eosinophils have been developed. The collection of exhaled breath condensate is a simple, noninvasive approach that comprehensively samples the lower respiratory tract. It is currently used as a research and diagnostic tool, yielding information on the degree and type of inflammation in the lung, and is most often used to measure cysteinyl leukotrienes and carbon monoxide as potential markers of inflammation. more
With further developments, such an approach may ultimately have a role in the clinic. Measurement of sputum eosinophil count and nitric oxide in exhaled breath have also been shown to have value in the diagnosis and management of asthma.
Allergic rhinitis is a highly prevalent disease affecting 15 to 50% of people worldwide. It is a chronic inflammatory disorder that affects patient quality of life and is associated with comorbid diseases such as asthma. A study from the University of Genoa of the prevalence of asthma and allergic rhinitis in naval recruits in Italy has shown that the incidence of rhinitis in asthmatic patients increased from 41% in 1983 to 77% in 1993 to 1995. Epidemiologic stud-ies have shown that up to 78% of patients with asthma have nasal symptoms and that rhinitis is an almost universal phenomenon in patients with allergic asthma.