Cellular proliferation of mucosa-associated lymphoid tissue with otitis media: a preliminary study

Histopathologic and immunohistochemical analyses were used to investigate the cellular proliferation of mucosa-associated lymphoid tissue (MALT) in human temporal bones with and without evidence of otitis media (OM). Anti-proliferating cell nuclear antigen (PCNA) antibody (clone PC10) was applied after the antigen retrieval procedure. Positive PCNA expression was observed in temporal bones that had been stored for 10 to 31 years in 80% ethanol. In specimens with purulent OM, the MALT had faint germinal centers (GCs). Positive PCNA expression in the MALT was moderate and scattered. In specimens with mucous OM, the MALT had complete GCs. Positive PCNA expression in the MALT was moderate to strong, and the distribution of PCNA-positive cells was associated predominantly in the GCs, the mucosal epithelial layer, and/or the subepithelial layer. In specimens with serous OM, the MALT also had complete GCs. However, the PCNA expression was weak and scattered, and appeared to be similar to that of the MALT in the temporal bones without OM. These results indicate that the cellular proliferation of MALT in the temporal bone might reflect the activity that produces secretory IgA against invasion of foreign antigens. However, further studies are needed to elucidate whether the PCNA expression within MALT in the eustachian tube and middle ear is associated with a mucosal immune response to inflammation as in OM.