Immunohistochemical localization of alpha 1-antitrypsin and alpha 1-antichymotrypsin in salivary pleomorphic adenomas.

Immunohistochemical identification of alpha 1-antitrypsin (alpha 1-AT) and alpha 1-antichymotrypsin (alpha 1-ACh) in pleomorphic adenomas of salivary glands is reported in order to compare their distribution profiles with those of lysozyme and lactoferrin, already described elsewhere. Normal salivary glands indicated positive alpha 1-AT staining in ductal segments and had no alpha 1-ACh in any glandular cell. Pleomorphic adenomas displayed moderate positivity to alpha 1-AT staining in duct-like, tubular and glandular epithelia which was particularly intense in luminal cells. The limited number of tumour cells which showed duct-like structures with a single cellular layer arrangement, displayed the highest staining to alpha 1-ACh. Strongly alpha 1-AT positive tumour cells located on the inner side of luminal cavities were also markedly positive to alpha 1-ACh. Spindle shaped tumour cells existed outside tubular and ductal structures and were negative to alpha 1-AT and alpha 1-ACh. Distribution of alpha 1-AT in salivary glands was similar to that of lysozyme as is usual in ductal segments or their transformed cells, and occurrence of alpha 1-ACh localization rather resembled that of lactoferrin, with occurrence in acinar compartments and changed epithelia within acini. The biological role of a specific immunohistochemical distribution of alpha 1-AT and alpha 1-ACh in pleomorphic adenomas may be associated with a self regulating mechanism which inhibits degradation by tissue proteinases.