| Research Abstract |
It is generally recognized that epithelial cytokeratins (CKs) are expressed in tissue-specific patterns and reflect differentiation, functional specialization, and pathological alteration of the cells. Therefore, differentiated epithelial cell types can be distinguished from each other by their selective expression of particular sets of CKs. To determine the characteristics of metaplastic and hyperplastic changes of alveolar-lining epithelial cells in the lungs of idiopathic interstitial pneumonia (IIP), the expression of individual CKs was studied immunohistochemically using monospecific anti-CK monoclonal antibodies (anti-CK 7, 8, 10, 13, 14, 16, 17, 18, 19). Biopsy specimens from 17 patients with IIP and normal lung tissues (NL) from 7 with lung cancer were studied.
In the IIP specimens, several kinds of altered epithelial cells were observed, and showed characteristic changes in CKs expression, especially in CK 8, 14, and 17 compared with those in NL; hyperplastic type II cells (exp
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ressed increased-CK 7, 8, and 19, no CK 17), flattened or stratified squamous metaplastic cells (expressed increased-CK 17 and 14, co-expressed CK 7, 8, and 19), bronchiolar metaplastic cells (increased-CK 7, 8, and 19, co-expressed CK 14 and 17), cuboidal metaplastic cells (increased-CK 7, 8, 17, and 19). The quantification of individual CKs in the tissues by enzyme-linked immunosorbent assay revealed increased expression of CK 8, 14, and 17 in IIP lung tissues compared to NL. These results were consistent with the immunohistochemical observations. The hyperplastic and bronchiolar metaplastic nature was demonstrated by their increased expression of simple CKs without CKs-alteration. The squamous metaplastic nature was demonstrated by their CKs-alteration, appearance of CK 17 and 14.
These data indicate the possibility that epithelial cells are altered not only in shape but also in differentiation and function. Epithelial alterations may be considered one of the important factors in the pathogenesis of IIP. Less
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