Increased percentage of mast cells within sinonasal mucosa of chronic rhinosinusitis with nasal polyp patients independent of atopy.

Background: Initial attention on the pathophysiology of chronic rhinosinusitis (CRS) has focused on eosinophils. Other immune cells such as mast cells (MCs) have been identified and appear to be elevated in CRS with nasal polyp (NP) patients. MCs are commonly linked to immunoglobulin E (IgE)-mediated inflammatory changes characterized by elevated T helper 2 cytokines. Although atopy is a common comorbid condition with CRS, the objective of this study was to determine if elevated MCs are linked primarily to atopic status in CRS patients and to understand the significance of MCs in the pathophysiology of CRS.

Methods: Ethmoid sinonasal mucosa from patients undergoing endoscopic sinus surgery was harvested from 3 groups: healthy control (HC), CRS without NP (CRSsNP), and CRS with NP (CRSwNP) and analyzed by flow cytometry to quantify CD117(+) /CD203c(+) MCs and CRTH2(+) CD4(+) T cells. Relative expression of prostaglandin D(2) synthase in ethmoid mucosa was determined by quantitative real-time polymerase chain reaction (PCR).

Results: MCs were significantly elevated in CRSwNP patients as compared to CRSsNP patients and HCs. This elevation was not solely dependent on the presence of IgE-mediated hypersensitivity. Relative expression of prostaglandin D(2) synthase was also increased in CRSwNP patients along with an associated presence of a CRTH2(+) memory CD4(+) T cell population.

Conclusion: Elevated percentages of MCs are found in the sinonasal mucosa of CRSwNP patients, regardless of atopic status. Secreted by MCs, elevated prostaglandin D(2) may play a role in the recruitment of CRTH2(+) cells to the inflamed mucosa of CRSwNP patients.