Histochemical study on keratin distributions and lectin-bindings in lining epithelia of jaw cysts.

Epithelial linings of 170 post operative maxillary cysts (POMCs) were microscopically examined, and correlations between lining epithelia and clinical findings were investigated. Then, using 45 of 170 POMCs (including ciliated (38), squamous (4), and composite lining epithelia (3 cases)), 30 radicular cysts (composed of ciliated (2), non-keratinized squamous (25) and of these composite epithelia (2), and keratinized epithelium (1)), and also using 25 dentigerous cysts revealing keratinized or non-keratinized epithelia in 8 and 17 cases, respectively, lectin-bindings and keratin localization were histochemically examined.Ninety walls of the subjected POMCs were lined with ciliated columnar epithelium, and linings of cuboidal, squamous and their combinations were seen in 6, 19, and 20 cases, respectively. Many POMCs lined with squamous epithelium revealed infection during past history, and a correlation between squamous lining and the infection was noted. RKSE60 keratin (56. 5 KD) only existed in the keratinized layer of squamous linings, while RGE 53 keratin (45 KD) was detected not only in all columnar epithelia, but also in all POMCs lined with squamous epithelia and 4 cases of maxillary radicular cysts. Tissue culture study of rabbit respiratory ciliated epithelium revealed that squamous cells, seemingly derived from originally columnar epithelium, and some newly proliferated squamous cells, induced with prostaglandin E1, E2 and dibutyryl cyclic AMP, reacted with RGE53 antibody. RGE53 keratin was therefore considered to be continuously maintained even after squamous metaplasia. From these results, it seems certain that epithelial linings of maxillary radicular cysts are sometimes derived from the respiratory epithelium associated with squamous metaplasia, and that RGE53 keratin is a useful marker for identification of metaplastic squamous cells.Most squamous epithelia bound strongly with SBA, Con A and UEA-I, while columnar epithelia showed weak bindings. Only a few linings of the tested cysts bound with SVGA. Among these lectins tested, SBA bindings revealed the most contrastive dramatic difference between both epithelia. Con A bound most prominently to squamous linings, and binding of UEA-I and SBA followed in this order. RKSE60 keratin-positive (i.e. keratinized squamous) epithelia had no glycoconjugates with SBA on basal cells. Contrarily, basal cells negative for this keratin had some lectin-binding sugar residues in most cases. From the above findings and other previous reports regarding keratin localization and lectin-binding in reduced enamel epithelium and dental lamina, it seems likely that keratinized lining of some dentigerous cysts may be derived from the early stage of tooth germ development. Metaplastic squamous epithelia intensely bound with SBA, Con A and UEA-I throughout the whole layer, and ciliated epithelium coexisting with squamous cells had similar staining patterns to those of metaplastic squamous epithelium. Ciliated epithelia of radicular cysts were also positive for SBA, Con A and UEA-I. Additionally, cultured respiratory epithelium gradually increased SBA binding ability corresponding to the degree of metaplastic change. Taking these facts into consideration, it is therefore likely that lectin binding sugar residues are expressed in advance on squamous metaplasia-ready columnar cell surfaces.