Abstract
Objectives:
Chronic rhinosinusitis with nasal polyposis (CRSwNP) is characterized by B cell inflammation. We sought to determine whether immunoglobulin class switch recombination (CSR) occurred locally within polyps and to quantify the expression of proteins involved in regulating CSR. Germline transcripts (GLTs) are produced during CSR, and activation-induced cytidine deaminase (AICD) is an enzyme that is required for CSR. Thus, GLT and AICD expression can be used as markers for CSR.
Methods:
Polyp (n = 12-37), tonsil (n = 7), and uncinate tissue (UT) from patients with CRSwNP (n = 9), CRSsNP (n = 10), and normal controls (n = 11-12) were collected. Quantitative reverse transcriptase polymerase chain reaction for GAPDH, GUSB (housekeeping genes), AICD, IL-15, iNOS, BAFF, and A1, A2, G1, G4, and E GLT was performed using cDNA from tissue. Relative expression was calculated in relation to a housekeeping gene.
Results:
AICD expression was significantly increased in tonsils compared with all other groups (P < .05), and polyp AICD expression was significantly elevated compared with UTwNP and UTsNP (P < .01). Tonsils expressed significantly more A2 GLT than all other groups (P < .05). E GLT was significantly increased in polyps versus UTnl (P < .05). G1 GLT was increased in polyps compared with all other groups (P < .05 vs UTwNP). G4 GLT was also increased in polyps compared with all other tissues, but this did not reach significance. Only IL-15 showed significantly increased expression in polyps versus UTnl and UTwNP (P < .01).
Conclusions:
These results suggest that local CSR is occurring in polyps of patients with CRSwNP.
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