Keratins versus epithelial membrane antigen in tumor diagnosis: an immunohistochemical comparison of five monoclonal antibodies.
Among the monoclonal antibodies capable of detecting epithelial lineage, some recognize keratin and others identify antigens of epithelial membranes. Of the latter, the most commonly used is directed against an antigen present in cell membranes derived from milk fat globules, epithelial membrane antigen (EMA). To determine their relative sensitivity and specificity and hence their diagnostic value, we compared four commercially available monoclonal antibodies to low-molecular-weight keratins--AE1, CAM 5.2, PKK1, and 35 beta H11--with the monoclonal antibody to EMA (anti-EMA). We studied 383 samples of human neoplasms of diverse histogenetic types and degrees of differentiation. Anti-EMA was found to be less sensitive than the monoclonal antibodies to keratin in several epithelial tumors, including tumors of the prostate (11 of 13 negative), gastrointestinal tract (13 of 34 negative), and thymus (seven of eight negative). Anti-EMA was also less sensitive in mesotheliomas (nine of 24 negative). Of the embryonal carcinomas, all stained with the monoclonal antibodies to keratin, whereas none stained with anti-EMA. False-positive staining with anti-EMA was seen in two of 14 T-cell lymphomas. We conclude that the monoclonal antibodies to low-molecular-weight keratins are more sensitive and specific for the identification of epithelial origin of neoplasms than is monoclonal anti-EMA. Anti-EMA should not be used as the sole marker of epithelial differentiation in tumor diagnosis.
D000230:Adenocarcinoma / Q000175:diagnosis; D000911:Antibodies, Monoclonal; D003110:Colonic Neoplasms / Q000175:diagnosis; D005189:False Positive Reactions; D006651:Histocytochemistry; D006801:Humans; D007633:Keratins / Q000032:analysis*; D008223:Lymphoma / Q000175:diagnosis; D008297:Male; D008565:Membrane Proteins / Q000032:analysis*; D018396:Mucin-1; D009369:Neoplasms / Q000175:diagnosis*; D011471:Prostatic Neoplasms / Q000175:diagnosis
D000911:Antibodies, Monoclonal; D008565:Membrane Proteins; D018396:Mucin-1; D007633:Keratins