D2-40 immunohistochemical assessment of lymphangiogenesis in normal and edematous sinus mucosa and nasal polyp

OBJECTIVE: The lymphatic system plays an important role in the maintenance of tissue fluid homeostasis, which facilitates interstitial protein transport. Until recently, the lymphatic system of the sinonasal mucosa has been relatively poorly studied. The authors aimed to investigate the distributional and quantitative changes of the lymphatic vessels in inflammatory sinus mucosa and nasal polyps in comparison with healthy sinus mucosa using D2-40 antibody. METHODS: Immunohistochemistry and Western blotting with D2-40 antibody were applied to normal and edematous ethmoid sinus mucosa and nasal polyps. The number, size, and length densities of lymphatic vessels were evaluated using tissue sections and whole mount preparations. RESULTS: Most lymphatic vessels in normal and edematous ethmoid sinus mucosa were distributed in the subepithelial layer. Some of these vessels were dilated, whereas others were compressed and had a slit-like lumen. No D2-40 positive vessels were found in samples of nasal polyps. Lymphatic vessels showed no statistically significant difference in their number, size, or length density between normal and edematous ethmoid sinus mucosa. Western blot also showed no differences in their expression levels. CONCLUSION: These findings indicate that lymphangiogenesis does not occur in edematous ethmoid sinus mucosa, which may not reuptake interstitial fluid efficiently in inflammatory conditions, resulting in the formation of mucosal edema in chronic inflammation.