Tissue distribution of a coelomic-epithelium-related antigen recognized by the monoclonal antibody OC125

Our plain-English summary of Tissue distribution of a coelomic-epithelium-related antigen recognized by the monoclonal antibody OC125, by S.E. Kabawat, R.C. Bast, A.K. Bhan, et al (International Journal of Gynecological Pathology, 1983).

The study

• Authors: S.E. Kabawat, R.C. Bast, A.K. Bhan, W.R. Welch, R.C. Knapp, R.B. Colvin
• Journal: International Journal of Gynecological Pathology
• Published: 1983;2(3):275-85
• Cited by: 551 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

OC125, a murine monoclonal antibody, recognizes an antigenic determinant (CA125) that is associated with greater than 80% of epithelial ovarian neoplasms of serous, endometrioid, clear cell, and undifferentiated types. In the present report, a sensitive biotin-avidin immunoperoxidase technique was used to determine reactivity of OC125 with normal adult and fetal tissues, as well as with neoplasms of nonovarian origin. In fetal tissues, the antibody reacted with amnion and with derivatives of the coelomic epithelium, i.e., the müllerian epithelium and the lining cells of the peritoneum, pleura, and pericardium. Among adult tissues, OC125 reacted with the epithelium of fallopian tubes, endometrium, and endocervix. The CA125 determinant was also detected on mesothelial cells in the adult pleura, pericardium, and peritoneum, particularly in areas of inflammation and adhesion. Curiously, the surface epithelium of normal fetal and adult ovaries, thought to be derived from coelomic epithelium, did not express the determinant, except in inclusion cysts, areas of metaplasia, and papillary excrescences. Of neoplastic tissues of nonovarian origin, OC125 reacted consistently only with adenocarcinomas of the endocervix, endometrium, and fallopian tube, and with mesotheliomas. Only seven of 64 nongynecological tumors tested reacted with OC125. Thus, OC125 detects a differentiation antigen shared by fetal coelomic epithelium and its derivatives in the fetus and the adult. Apparently, this antigen disappears early in the course of formation of the ovarian epithelium and is reexpressed in certain reactive and neoplastic lesions, a process that could be termed "molecular metaplasia."

In plain English

This laboratory study tested where a mouse antibody, OC125, binds in human tissue. The antibody recognizes a marker the authors call CA125. The study did not examine asbestos or any other exposure. Frozen tissue sections from surgery, autopsies and therapeutic abortions were stained, including eight fetuses, normal adult tissues and tumors. In fetuses, OC125 bound to the müllerian ducts, the linings of the peritoneum, pleura and pericardium, and the amnion, but not to the surface of the fetal ovary. In adults it bound to the lining of the fallopian tube, endometrium and endocervix, and to mesothelial cells of the pleura, pericardium and peritoneum, especially in areas of inflammation and adhesion. Normal ovarian surface cells did not stain. Of 64 nongynecologic tumors (tumors not of the female reproductive organs), one of two malignant biphasic mesotheliomas reacted, seen only in cells from pleural fluid. Six of 60 tumors from noncoelomic tissues reacted, all lung and breast adenocarcinomas. The authors concluded that OC125 detects a marker associated with the coelomic epithelium and almost all its normal and tumor derivatives. They had not established whether the same molecule carried it in every tissue.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory immunohistochemistry study: frozen tissue sections were stained with the OC125 antibody using an avidin-biotin immunoperoxidase technique
• Who was studied: Human tissue samples studied at Boston hospitals (Massachusetts General Hospital, Brigham and Women's Hospital, Dana-Farber Cancer Institute): eight fetuses from therapeutic abortions (first and second trimester), normal adult tissues, ovarian tumors, other gynecologic tumors, and 64 nongynecologic tumors. No study dates are given.
• Exposure: No asbestos or other exposure was studied; the study examined which tissues the OC125 monoclonal antibody binds to
• Main results:
  • In fetal tissue, the CA125 antigen was found in the müllerian ducts and in the cells lining the fetal peritoneum, pleura and pericardium
  • The surface epithelial cells of the fetal ovary did not react with the antibody
  • In adults, the antigen was found in the epithelial cells of the fallopian tube, endometrium and endocervix
  • In adults, the antigen was present in mesothelial cells lining the pleura, pericardium and peritoneum, especially in areas of inflammation and adhesion
  • Normal adult ovarian surface epithelium did not react, although cells lining inclusion cysts, papillary excrescences and adhesions with tall columnar metaplasia did
  • Among gynecologic tumors, OC125 reacted with the majority of adenocarcinomas of müllerian origin (uterine or fallopian); squamous cell carcinomas of the cervix did not react
  • Among the 64 nongynecologic tumors tested, one of two malignant biphasic mesotheliomas reacted; the reaction was seen only on malignant cells in cytosmears from pleural effusion, as no frozen tissue was available from that case
  • Only six of 60 tumors from noncoelomic tissues reacted, and all six were adenocarcinomas of the lung and breast
  • Normal breast, lung and colon from patients without tumors were negative, but staining was sometimes seen in breast ducts, bronchiolar epithelium and colonic mucosal cells next to tumors
• The authors' conclusion: The authors concluded that OC125 detects a differentiation antigen associated with the coelomic epithelium and almost all of its normal and neoplastic derivatives, which normal ovarian surface epithelium curiously does not express
• Limitations the authors state:
  • The authors had not yet established whether the marker is carried by the same molecule in the various normal and tumor tissues
  • The antigen could not be demonstrated in formalin-fixed, paraffin-embedded tissue sections, which the authors attribute to the antigen appearing heat labile
  • The authors cautioned that their data suggesting a mesenchymal origin of amnion should be examined with caution, since sharing a molecule may not mean a shared embryological origin
  • Study of very early embryos would be required to test one explanation for the lack of staining in ovarian surface epithelium

Topics

Medical terms in this study, explained in our Lexicon: Epithelium, Monoclonal Antibody, Neoplasm, Peritoneum, Pleura, Pericardium, Mesothelial Cells, Inflammation.

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