Researchers identified immunological markers in nasal secretions and tears is becoming essential in the study of allergic diseases. The collection procedure of nasal and ocular secretions directly influences the results, thus it is of paramount importance to validate and standardize the sampling process.
Current techniques for nasal secretions sampling are mainly based on three principles: a collection of spontaneous secretions, nasal washings, and absorption. Collection of spontaneous secretions is appropriate in subjects with nasal hypersecretion, whereas in healthy individuals the collected volume is frequently insufficient. Nasal washings are associated with an unpredictable, high dilution and concentrations of markers often fall below detection limits of immunological assays.
The analysis of human secretions, such as nasal fluid and tears, provide valuable information on pathophysiological aspects of allergic diseases. There is increasing evidence of its potential role in allergology diagnostics and in immunotherapy monitoring.
However, testing nasal fluids (and tears) still remains a research domain and is neither included in practice guidelines nor common in clinical practice. Major concerns are the inconsistent data on biomarker concentrations as their low concentration in secretions
Absorption seems to provide the best compromise between sufficient sample amounts and detectability of inflammatory mediators and immunoglobulin E. Tear samples can be obtained by glass capillary tubes, filter paper strips, and ophthalmic sponges. Volumes are however small or highly diluted through reflex tearing.
Secretions reflect the local inflammatory activity and provide valuable information about the immunological reaction to allergens at the target organ. There is increasing evidence of the potential clinical role of their analysis, for diagnosis, and monitoring of allergic rhino-conjunctivitis. Appropriate collection and processing is very important and requires special attention.