A profound elevation of mast cells was detected within the epithelium and glands of nasal polyps in patients with chronic rhinosinusitis, suggesting that these cells have distinct phenotypes that vary by tissue location, according to study results.
Researchers collected nasal tissue and nasal lavage fluid from patients with chronic rhinosinusitis and nasal polyps (CRSwNP; n=91), chronic rhinosinusitis without polyps (CRSsNP; n=70) and a control group (n=42) to analyze the presence, localization and phenotype of mast cells. Using real-time PCR, they measured the mast cell proteases tryptase, chymase and carboxypeptidase A3 to analyze mRNA. They also used ELISA, immunohistochemistry and immunofluorescence to gauge mast cell protease proteins.
In the CRSwNP group, tryptase mRNA was significantly increased (P<.001) compared with uncinate tissue from patients in the control and CRSsNP groups. The CRSwNP patients also showed elevated tryptase protein in their nasal polyps and nasal lavage.
Mast cells expressing all three proteases were abundant within the glandular epithelium of polyps, but were not present in normal glandular structures. Researchers also found tryptase and carboxypeptidase A3, but not chymase in the mast cells detected in the epithelium in polyps.
“Clearly further study will be required to determine the mechanism of mast cell accumulation within the epithelium of [nasal polyps], both at the mucosal surface and within submucosal glands,” researchers concluded. “A unique phenotype of mast cells in nasal polyp glands may have a pathogenic role in chronic rhinosinusitis.”