Immunohistochemical studies on tumor antigen-4 in squamous cell carcinoma of uterine cervix.

Abstract
Immunohistochemical localization of Tumor Antigen 4 (TA-4) in squamous cell carcinoma (SCC) tissues of the uterine cervix was studied by means of the immunoperoxidase methods. Light microscopic detection of TA-4 was carried out by means of the avidin-biotin-peroxidase complex method on formalin-fixed paraffin-embedded sections from 92 cases of invasive cervical cancer of the uterus. These tumors were histologically SCC, consisting of 68 of the large cell non-keratinizing (LNK) type and 24 of the keratinizing (K) type. TA-4 positive cells were detected in 65% of LNK cases and 100% of K cases. Positively stained neoplastic cells were seen frequently around the hyperparakeratotic lesions, and they showed a tendency to keratinization. TA-4 localization was also confirmed in the cells of stratum spinosum of the non-cancerous squamous epithelium. Subcellular localization of TA-4 was studied by the preembedding indirect immunoperoxidase method. TA-4 was localized in the cytosols of the neoplastic cells, but not in tonofilaments. It was suggested that TA-4 was a structural protein of SCC. Therefore, unlike keratin, TA-4 can be considered as an index of differentiation of SCC cells, and TA-4 should be useful as a tumor marker which expresses the characteristics of the neoplastic tissue during squamous maturation.