Immunolocalization of cystatin A in neoplastic, virus and inflammatory lesions of the uterine cervix.

Cystatin A was immunohistochemically demonstrated in the normal squamous epithelium of the uterine cervix, particularly in the parabasal and superficial cell layers whereas it was absent or scanty in the basal cells and in areas with parakeratosis. Cystatin A was also found in neoplastic lesions (dysplasia, carcinoma in situ and squamous cell carcinoma), but less abundant than in normal squamous epithelium. The immunoreaction in intraepithelial neoplasia was closely related to the degree of morphological maturation of the squamous cells with more abundant cystatin A in low grade dysplasia and less in high grade dysplasia and carcinoma in situ. In squamous cell carcinoma, cystatin A was often abundant in highly differentiated areas and almost absent in poorly differentiated ones. Cystatin A was found in the squamous epithelium in herpes and in condylomatous lesions. It was also found in the cytoplasm of neutrophils, but not in lymphocytes and plasma cells. In unspecific cervicitis, cystatin A was found extracytoplasmatically as small vesicles in the epithelial-stromal junction. The implications of cystatin A in neoplastic, virus, and inflammatory processes are discussed.