In the upper airway, the production of
antimicrobial peptides (AMPs) protects against bacteria, viruses and fungi. Previous investigations have revealed downregulated expression of AMPs in different manifestations of allergic disease. In this study, we examined the expression of LL-37, Ribonuclease7 (
RNase7) and
Liver-expressed antimicrobial peptide 2 (LEAP-2) in tonsillar tissue and studied a possible relation to
seasonal allergic rhinitis (SAR). Tonsils, obtained from patients with SAR and nonallergic controls, were examined for the occurrence of LL-37,
RNase7 and LEAP-2 with real-time RT-PCR and immunohistochemistry. Tonsillar mononuclear cells were cultured in presence or absence of LEAP-2 or LL-37 and analyzed for
cytokine levels using ELISA.
mRNA and
protein for LL-37,
RNase 7 and LEAP-2 were found in all tonsils. Immunohistochemistry revealed prominent staining for LL-37 and
RNase7 in the tonsillar epithelium, whereas a moderate staining was seen with LEAP-2. Real-time RT-PCR showed a downregulation of
RNase7 and LEAP-2 in the allergic as compared to the nonallergic group. Mononuclear cells cultured in presence of LEAP-2 or LL-37 demonstrated reduced levels of
IL-10. The present study demonstrates the presence and function of LEAP-2, LL-37 and
RNase7 in tonsils. Moreover, a downregulation of LEAP-2 and
RNase7 is seen in SAR patients, indicating that allergic individuals may be more susceptible to
respiratory tract infections due to an impaired antimicrobial defense.