Nasal mucus as a diagnostic fluid in human physiology and disease

Clinical and molecular diagnosis of disease has focused on blood and urine as major repositories of this information. Our studies have focused on nasal mucus as a practical, readily available fluid upon which to obtain clinical and molecular information to understand human physiology and to diagnose human disease. We have found nasal mucus to be a repository for unique information regarding bodily functions. To demonstrate its relevance we compared levels of many proteins and signal substances in nasal mucus with those in blood, urine and saliva using a 96 plate colorimetric ELISA assay. In this manner we evaluated leukemia inhibitor factor (LIF), macrophage inhibitory factor (MIF), placental growth factor (PGF), FAS ligand, substance P, endostatin, erythropoetin, granulocyte macrophage colony stimulatory factor (GMCSF) and many other substances in these biological fluids. LIF was present in nasal mucus at levels ranging from 40–70pg/ml but was not found in either plasma, urine or in saliva. MIF was present in nasal mucus in 94% of subjects but in serum in only 62% of subjects, in urine in 56% and in saliva in 50%; levels in nasal mucus were 5–35 times higher than in plasma, 3–30 times higher than in saliva and 3–20 times higher than in urine. Similar results were found with several other substances, the substance either found only in nasal mucus and not in other biological fluids or with levels significantly higher in nasal mucus than in any other biological fluid. These results indicate that, while specific mechanisms for presence of these substances in nasal mucus are unclear, their presence reflects unique and important indicators of both human physiology and disease.