Cellular distribution of mucosa-associated lymphoid tissue with otitis media in children

This study examined mucosa-associated lymphoid tissue (MALT) in the eustach ian tube (ET), middle ear (ME), and mastoid antrum (MA) in 163 celloidin-em bedded temporal bones from children with or without otitis media. Otitis me dia was defined by the presence of histopathologically identified inflammat ory cell infiltration in the mucosa or cavity of the ME. We found MALT in t he ET in 30 cases (46.2%), in the ME in 19 cases (29.2%), and in the MA in 4 cases (6.2%) out of 65 cases of otitis media, and in the ET in 7 (7.1%), in the ME in 0, and in the MA in 0 out of 98 specimens without otitis media . No MALT appeared in any children under the age of 1 month. Immunohistoche mical methods were used to investigate MALT in 12 horizontally cut temporal bones with OM, The follicular area contained OPD4-positive (helper-inducer T) cells and a few CD8-positive (cytotoxic and suppressor T) cells, wherea s the parafollicular area contained OPD4-positive and CD8-positive T cells. CD57-positive (natural killer) cells were confined to the germinal center. CD30-positive (activated T and B) cells were observed throughout the folli cles. A few CD15-positive (granulocyte, monocyte) cells were found in the f ollicles. Histopathologic and immunohistochemical findings were indistingui shable for MALT in the ET, ME, and MA. Our results suggest that MALT may be a mechanism for producing a rapid and massive local immune reaction to rep eated bacterial infections via the ET.