Carcinoembryonic antigen and nonspecific cross-reacting antigen in medullary carcinoma of the thyroid

Carcinoembryonic antigen (CEA) and nonspecific cross-reacting antigen (NCA) were studied immunohistochemically in formalin-fixed, paraffin-embedded tissues of 73 cases of medullary carcinoma of the thyroid (MTC) using 2 polyclonal antibodies (CEA antisera cross-reactive with or without NCA), 3 monoclonal antibodies recognizing epitopes only on CEA, and one monoclonal antibody against NCA. The staining patterns of the 5 antibodies against CEA in MTCs were not different, and they reacted with 86.3% of all cases. With regard to the effects of fixatives on the staining patterns, samples fixed with formalin or 4% paraformaldehyde demonstrated CEA immunoreactivity in both the cell membrane and cytoplasm. In Bouin-fixed tissue, the immunoreactivity was predominant on the cell membrane, whereas cytoplasmic positivity predominated in alcohol-fixed specimens. Thus the difference in fixatives used in previous studies does not appear to be a major reason for the difference in the reported incidence of CEA-positive MTCs. It is concluded that CEA is still a useful tumor marker for MTC and that it is detectable only in thyroid tumors originating from C cells, as seen in our series. The epitope defined by monoclonal antibody F106-88, present only on NCA, was found in 42.5% of all cases (49.2% of CEA-positive MTCs). The NCA immunoreactivity was located in the tumor cell cytoplasm as globular aggregates, which were also labeled for CEA.     

Immunohistochemical Demonstration of Nonspecific Cross-reacting Antigen in Normal and Neoplastic Human Tissues Using a Monoclonal Antibody: Cornparison with Carcinoembryonic Antigen Localization

Nonspecific cross-reacting antigen (NCA) immunoreactivity was localized in normal and neoplastic human tissues using a monoclonal antibody to 55, 90 and 95 kDa molecules of NCA. This was compared to the localization of immunoreactive carcinoembryonic antigen (CEA) as demonstrated by polyclonal and monoclonal antibodies. In frozen sections, CEA was localized in normal surface epithelium of the stomach and colon where NCA was only weakly detected. Type 1 and type 2 like pneumocytes were positive for NCA, while CEA was localized only in type 2-like pneumocytes. CEA and NCA were both demonstrated in ductal cells of frozen pancreatobiliary and mammary tissues. The antigenicity of CEA and NCA in normal tissues was significantly lost after paraffin embedding as compared to frozen sections. NCA was consistently demonstrated in eccrine sweat glands embedded in paraffin. In various tumor tissues, CEA and NCA were colocalized and expression increased sufficiently to be detected in paraffin sections. Adenocarcinomas of the stomach and colon and cystadenocarcinoma of the pancreas, as well as neuroendocrine carcinomas of the lung and thyroid, showed a CEA predominance over NCA. In ductal adenocarcinomas of the pancreas and breast and in cholangiocarcinoma, NCA reactivity was greater than CEA. Keratiniring foci of most squamous cell carcinomas of mucosal origin and some adenocarcinomas equally expressed both. Hepatocellular carcinoma, lobular mammary carcinoma and papillary thyroid carcinoma were positive only with unabsorbed polyclonal antibody which widely recognizes CEA-related substances. Renal cell carcinoma, prostatic adenocarcinoma, transitional cell carcinoma, anaplastic carcinomas, choriocarcinoma and basal cell carcinomas showed little or no immunoreactivity. Hence the relative ratio of CEA/NCA expression in tumors was dependent on the tissue of origin and histologic type. The cytoplasmic granular staining of NCA in cancer cells was a noteworthy difference from the plasma membrane-associated localization of CEA. Acta Pathol Jpn 40: 85–97, 1990.     

Immunohistochemical demonstration of nonspecific cross-reacting antigen in normal and neoplastic human tissues using a monoclonal antibody. Comparison with carcinoembryonic antigen localization

Nonspecific cross-reacting antigen (NCA) immunoreactivity was localized in normal and neoplastic human tissues using a monoclonal antibody to 55, 90 and 95 kDa molecules of NCA. This was compared to the localization of immunoreactive carcinoembryonic antigen (CEA) as demonstrated by polyclonal and monoclonal antibodies. In frozen sections, CEA was localized in normal surface epithelium of the stomach and colon where NCA was only weakly detected. Type 1 and type 2-like pneumocytes were positive for NCA, while CEA was localized only in type 2-like pneumocytes. CEA and NCA were both demonstrated in ductal cells of frozen pancreatobiliary and mammary tissues. The antigenicity of CEA and NCA in normal tissues was significantly lost after paraffin embedding as compared to frozen sections. NCA was consistently demonstrated in eccrine sweat glands embedded in paraffin. In various tumor tissues, CEA and NCA were colocalized and expression increased sufficiently to be detected in paraffin sections. Adenocarcinomas of the stomach and colon and cystadenocarcinoma of the pancreas, as well as neuroendocrine carcinomas of the lung and thyroid, showed a CEA predominance over NCA. In ductal adenocarcinomas of the pancreas and breast and in cholangiocarcinoma, NCA reactivity was greater than CEA. Keratinizing foci of most squamous cell carcinomas of mucosal origin and some adenocarcinomas equally expressed both. Hepatocellular carcinoma, lobular mammary carcinoma and papillary thyroid carcinoma were positive only with unabsorbed polyclonal antibody which widely recognizes CEA-related substances. Renal cell carcinoma, prostatic adenocarcinoma, transitional cell carcinoma, anaplastic carcinomas, choriocarcinoma and basal cell carcinomas showed little or no immunoreactivity. Hence the relative ratio of CEA/NCA expression in tumors was dependent on the tissue of origin and histologic type. The cytoplasmic granular staining of NCA in cancer cells was a noteworthy difference from the plasma membrane-associated localization of CEA.     

Differential reactivities of carcinoembryonic antigen (CEA) and CEA-related monoclonal and polyclonal antibodies in common epithelial malignancies.

To evaluate the role of carcinoembryonic antigen (CEA) in solving problems of tumor histogenesis in surgical pathology, monoclonal antibodies to four distinct epitopes of CEA (E-Z-EM) were applied to paraffin sections of 303 epithelial neoplasms from multiple sites. Two epitopes were CEA specific (D14 and B7.1), one was shared with nonspecific cross-reacting antigen (NCA) (B7.8), and the fourth (B18) was common to CEA, NCA, and biliary glycoprotein antigen (BGP). A sample of the tumors (n = 110) was also stained with a polyclonal anti-CEA (DAKO). Gastrointestinal adenocarcinomas, including esophageal and gastric (n = 19), small intestinal (n = 8), colorectal (n = 56), biliary tract (n = 8), and pancreatic adenocarcinomas (n = 14), were consistently positive with all five antibodies. Other predominantly gland-forming carcinomas tested, comprising lung (n = 22), ovary (n = 18), and endometrium (n = 12), were either invariably negative with all five antibodies (endometrial adenocarcinoma, non-mucinous ovarian adenocarcinoma) or demonstrated selective and variable positivity (lung: D14, 50%; ovarian mucinous: D14, 50%). Among large polygonal cell carcinomas (hepatocellular carcinoma, renal cell carcinoma, melanoma, and adrenal carcinoma), only hepatomas stained positively, showing a distinctive canalicular staining pattern with the B18 (BGP epitope) (55%) and polyclonal antibody (50%). In the small polygonal cell carcinoma category, true CEA positivity was rare in breast (D14, 10% and B7.1, 14%) and never seen in prostatic carcinomas and carcinoid tumors. A subset of these breast (8 of 42), prostate (4 of 22), and carcinoids (4 of 7) showed exclusive positivity for the B18 antibody (NCA/BGP epitope). Ovarian serous papillary carcinomas (n = 14), papillary carcinomas of thyroid (n = 12), transitional cell carcinomas of the bladder (n = 11), and mesotheliomas (n = 3) were negative with all monoclonal antibodies. Metastatic carcinomas (n = 74) showed a similar pattern of reactivity to primary tumors. The authors conclude that CEA immunostaining may assist in identifying the histogenesis of epithelial tumors in several morphologic categories; that differential reactivities of the CEA monoclonal antibody panel exceed those of the polyclonal antibody; and that the discriminating power of the monoclonal panel is related to whether (1) CEA is or is not produced or (2) NCA or BGP is produced without concomitant CEA production. There is little evidence to support a concept of site-specific CEA species.     

Granular cell myoblastoma: an immunoperoxidase study using a variety of antisera to human carcinoembroyonic antigen

Immunoperoxidase staining using five antisera to human carcinoembryonic antigen (CEA), including a mouse monoclonal antibody, was performed to investigate the expression of CEA reactivity in ten cases of granular cell myoblastoma. The granular cells were negative with four of the antisera although control sections of CEA producing colon carcinoma were positive. The single positive antiserum gave intense granular cytoplasmic staining of all tumour cells in the ten specimens studied. This reactivity was abolished after absorption of the antiserum with a perchloric acid extract of human lung to remove cross-reacting antibodies against non-specific cross-reacting antigen (NCA); a procedure which did not affect the staining of colon carcinoma specimens. The results indicate that the granular cells do not contain CEA but express a related antigen and that care in the choice of primary antiserum is important if the immunocytochemical detection of this antigen is to be used as a diagnostic aid.     

Galectin-3 and carcinoembryonic antigen expression in medullary thyroid carcinoma: possible relation to tumour progression

AIMS: Galectin-3 is a beta-galactoside binding protein involved in multiple biological processes through interactions with complementary glycoconjugates. We analysed the expression and coexpression of galectin-3 and carcinoembryonic antigen (CEA), one of the putative galectin-3 ligands, in medullary thyroid carcinoma (MTC). METHODS AND RESULTS: An immunohistochemical study using monoclonal antibodies was performed on paraffin sections of 20 cases of sporadic MTC comprising 10 cases without and 10 cases with lymph node metastases at the time of surgery. CEA expression was found in all tumours, distributed predominantly in the cytoplasm and occasionally at the cell surface. In the majority of cases (18/20) moderate to strong intensity of staining was found in most of the cells. Positive cytoplasmic staining for galectin-3 was found in 16/20 cases, but varied in intensity and distribution from weak/focal (7/16) to moderate (7/16) or strong (2/16). More intense staining for galectin-3 was mainly associated with MTC cases involving lymph node metastases. Eight out of these 10 cases showed moderate to strong galectin-3 expression concomitant with CEA expression throughout the tumour tissue. CONCLUSIONS: These findings suggest that galectin-3 might play a role in the pathobiology of MTC. Simultaneous expression of galectin-3 and CEA in the same tumour cells at an advanced stage of MTC indicates the possibility of their autocrine cooperation during tumour progression.     

CEA immunoreactivity in metastatic malignant melanoma.

Immunohistochemical techniques may aid in the diagnosis of poorly differentiated metastatic tumors. Anti-carcinoembryonic antigen (CEA) antibodies have been used in the identification of epithelial neoplasms. However, recent unpublished data report CEA reactivity in malignant melanoma and melanoma cell lines. We studied 28 cases of known metastatic malignant melanoma with an antibody panel for CEA (polyclonal and monoclonal), AE1:3, S-100, and HMB-45. Reactivity for CEA (polyclonal) was seen in 15 of 28 (53%) cases: nine exhibited strong diffuse positivity, five moderate focal positivity, and one globular cytoplasmic staining. Focal reactivity for cytokeratin (AE1:3) was seen in three of 28 cases. HMB-45 staining was present in 23 of 28 (82%, including strong positivity in the cytokeratin-reactive cases). Staining for S-100 protein was strong in all cases. No staining was seen for CEA (monoclonal). CEA immunoreactivity is seen in a significant number of metastatic malignant melanoma cases. This may be due to CEA expression by tumor cells, or crossreactivity of the polyclonal antibody with substances such as nonspecific crossreacting antigen (NCA) that share antigenic sites with CEA. These findings emphasize the need for care in interpreting immunohistochemical results. Immunohistochemical evaluation of CEA should not be made alone, but only as part of a diagnostic antibody panel.     

Preservation of cluster 1 small cell lung cancer antigen in zinc-formalin fixative and its application to immunohistological diagnosis

Monoclonal antibodies reactive with cluster 1 small cell lung cancer antigen have been shown to be useful for the distinction of small cell from non-small cell tumours. In previous studies the antibodies have been applied to frozen sections and cold acetone-fixed tissues. However, one of three monoclonal antibodies that we produced, NCC-LU-243, reacted with some small cell lung carcinomas fixed in formalin solution and embedded in paraffin. The addition of zinc sulphate to the formalin solution at a concentration of 2% (v/w) greatly improved antigen immunoreactivity, and reactivity was retained even after prolonged fixation. Occasionally, immunoreactivity was present in a poorly differentiated adenocarcinoma with rosette-like structures. The monoclonal antibody NCC-LU-243 is thus of considerable potential value in the immunohistochemical diagnosis of small cell lung cancers.     

Carcinoembryonic antigen in medullary thyroid carcinoma: an immunohistochemical study applying six novel monoclonal antibodies

Six novel mouse monoclonal antibodies raised against carcinoembryonic antigen (CEA) were used to study 22 medullary, ten papillary, ten follicular, and eight anaplastic thyroid carcinomas. The antibodies CEA 12-140-5, -7, and -10 reacted with the same epitope group (GOLD 4), whereas antibodies CEA 12-140-1, -2, and -4 recognized different epitopes (GOLD 5, 2 and 1, respectively) on the CEA molecule. All medullary carcinomas of the thyroid (MCTs) were stained when the antibodies CEA 12-140-5, -7, and -10 were applied, whereas CEA 12-140-1 stained all but five MCTs; CEA 12-140-2 and CEA-12-140 -4 each stained all but two. The CEA immunoreactivity was predominantly located diffusely in the cytoplasm but occasionally was also concentrated along the cell membrane. CEA immunoreactivity was also observed in normal C-cells and C-cell nodules. The follicular, papillary, and anaplastic carcinomas were all CEA-negative with the monoclonal antibodies applied in this study. The differences in staining pattern of MCTs found with the various antibodies may be explained as a lack of expression of some epitopes in some tumors, or they may be due to a varying degree of masking of the epitopes by the extensive glycosylation of CEA and CEA-like substances.     

Comparison of immunoreactivity between two different monoclonal antibodies recognizing peptide and polysialic acid chain epitopes on the neural cell adhesion molecule in normal tissues and lung tumors.

A comparative immunohistochemical study of two different monoctonal antibodies against different epitopes on the neural cell adhesion molecule (N-CAM) was performed. Various normal tissues and lung tumors were examined for reactivity with NCC-LU-243, a monoclonal antibody which recognizes a peptide epitope on N-CAM, and monoclonal antibody 735 (MoAb 735), which reacts with a polysialic acid chain epitope on N-CAM. When acetone-fixed normal tissues were used, the immunoreactivities of MoAb 735 and NCC-LU-243 were not identical. In lung tumors, almost all small cell cancers (SCLC) and carcinoid tumors, and some non-SCLC were stained by both monoclonal antibodies. NCC-LU-243 stained the cell membrane only of almost all SCLC cells and clusters of non-SCLC cells. MoAb 735 stained the cell membrane of SCLC in a patchy manner and not only the cell membrane but also the cytoplasm of some non-SCLC. However cytoplasmic staining was evaluated as ‘not positive’. The number of positive cases and the size of the positive tumor cell population determined by cell membrane staining with MoAb 735 were smaller than those determined with NCC-LU-243 in both SCLC and non-SCLC cases. In routinely formalin-fixed materials, the immunoreactivity of both monoclonal antibodies, especially of NCC-LU-243, decreased after prolonged fixation as in surgically resected and autopsy materials. However, both monoclonal antibodies were found to be useful when materials were fixed for a short period of time as in biopsy specimens.     

抗癌胚抗原单链抗体与核心链霉亲和素基因的融合及在大肠杆菌的表达

制备抗癌胚抗原 (CEA )单克隆抗体的单链抗体 ,在保留抗原抗体结合位点的同时有效降低抗体的分子量不仅可减少人抗鼠抗体反应 (HAMA ) ,而且适合放射免疫显像。为纯化及核素标记抗体 ,将单链抗体基因与核心链霉亲和素基因融合并在大肠杆菌得到高效表达 ,表达量占菌体总蛋白的 2 4%。SDS PAGE和蛋白质印迹图谱显示表达产物分子量为 41kD ,与其基因编码蛋白质的理论推算值相符。表明融合蛋白能特异性地与生物素结合 ,RIA表明表达产物具有结合其特异性抗原CEA的能力 ,以HRP标记的生物素作为抗体进行蛋白质印迹在 41kD处可见表达条带。说明表达物不仅能与生物素结合且能特异性地与CEA结合。     

A novel CEA-cross-reacting antigen of molecular weight 140,000 expressed on human lymphoid cell lines

To investigate the possible expression of the carcinoembryonic antigen (CEA) gene family products on lymphoid cells, we screened 28 human cell lines derived from malignant lymphoid cells for reactivity with monoclonal antibodies (MAbs) against CEA and nonspecific cross-reacting antigen (NCA), which is one of the CEA gene family members. Six cell lines (four B cell lines and two non-T, non-B cell lines) were found to react, by a membrane immunofluorescence test, with an MAb, F34-187, which recognizes an antigenic determinant shared between CEA and NCA. None of the 15T cell lines was reactive with any MAbs tested. A glycoprotein antigen isolated with F34-187 from the cell surface showed an apparent molecular mass of ca 140 and 70 kDa in the glycosylated and deglycosylated forms, respectively, and was unreactive with MAbs specific for CEA or NCA, suggesting that the antigen is a new member of the CEA gene family.     

Immunohistochemistry in the diagnosis of malignant mesothelioma

Summary The histological diagnosis of malignant mesothelioma of the pleura, especially the distinction from peripheral adenocarcinoma of the lung, may be difficult. The immunohistochemical reports previously published on this subject show diverging results mainly because a variety of antibodies and staining techniques have been used by the different authors. To obtain comparable and reproducible results standard techniques and commercialized antibodies should be applied in routine pathology. In order to investigate the value of immunohistochemistry for the separation of the two entities formalin fixed and paraffin embedded blocks of 47 mesotheliomas and 22 adenocarcinomas were investigated with the PAP technique and commercially available antibodies to carcino-embryonic antigen (CEA), keratin, vimentin, epithelial membrane antigen (EMA), pregnancy specific antigen (SP₁), S-100 protein and monoclonal antibody lu-5 (mAB lu-5). CEA positivity was found in all 22 adenocarcinomas examined, but only 2/47 (4%) of all mesotheliomas showed a positive result. SP₁ was positive in 13/22 (59%) of the adenocarcinomas, whereas only 3/47 (6%) mesotheliomas were positive for this marker. No significant difference in the rate of positive cases in the adenocarcinoma and mesothelioma group could be found with the other above mentioned antigens. The results of our study indicate that especially CEA, but also SP₁ are valuable markers in the diagnosis of malignant mesothelioma.     

Effect of formalin fixation and epitope retrieval techniques on antibody 34betaE12 immunostaining of prostatic tissues.

Basal cell-specific, anti-high molecular weight cytokeratin (HMCK) antibody is often used to confirm the diagnosis of prostatic adenocarcinoma, particularly if limited amounts of tissue are available. HMCK is formalin sensitive and requires pretreatment by enzymes or heat if formalin-based fixatives are used. To date, the effect of prolonged formalin fixation on HMCK immunoreactivity has not been systematically studied; this is critical, because the diagnosis of malignancy is based on a negative immunoreaction. In this study, 5 tissue blocks obtained from each of 10 radical prostatectomy specimens were fixed in formalin from 6 hours to 1 month. HMCK immunostaining was performed with monoclonal antibody clone 34betaE12 after pretreatment of the sections by either enzymatic predigestion with pepsin, heat-induced epitope retrieval (HIER) with a microwave, or HIER with a hot plate. For scoring, the staining intensity at 6 hours of formalin fixation was considered as the baseline for that particular antigen retrieval technique. After pepsin predigestion or microwaving, there was progressive loss of HMCK immunoreactivity from 1 week or longer of formalin fixation. HIER with a hot plate yielded consistent results with no decrease in HMCK immunoreactivity with as long as 1 month of formalin fixation. The staining intensity was consistently stronger at all periods of formalin fixation when the hot plate method was used, compared with pepsin predigestion or microwaving. Generally weak HMCK positivity was observed in rare neoplastic cells of 3 of 10 specimens after hot plate HIER but not with pepsin predigestion or microwave antigen retrieval. This sporadic immunostaining of malignant cells was quantitatively and qualitatively distinct from the pattern seen in benign epithelium. We conclude that formalin fixation affects HMCK immunoreactivity over time and might impact its diagnostic usefulness. Efficacies of different antigen unmasking/epitope retrieval techniques vary and must be standardized for individual laboratories.     

Epithelial markers in pancreatic carcinoma: immunoperoxidase localisation of DD9, CEA, EMA and CAM 5.2.

Paraffin wax embedded, formalin fixed sections of 22 adenocarcinomas of the exocrine pancreas were stained with four mouse monoclonal antibodies: DD9-E7, an antibody raised against a human pancreatic tumour xenograft; carcino-embryonic antigen (CEA); epithelial membrane antigen (EMA); and cytokeratin (CAM 5.2). An indirect immunoperoxidase technique without enzyme pre-digestion and an affinity-purified sheep anti-mouse peroxidase conjugate were used. All of the tumours were positive for DD9-E7, EMA, and CAM 5.2. Twenty out of 22 were focally positive for CEA and the staining was often weak. As all of these adenocarcinomas were DD9-E7 positive, absence of staining for DD9-E7 in a tumour makes the diagnosis of adenocarcinoma of the exocrine pancreas very unlikely, and this is of value in distinction from endocrine carcinomas with a marked acinar pattern. The weak CEA staining distinguished pancreatic carcinomas from colorectal tumours. Because the distribution of staining for EMA and CAM 5.2 was no different from that previously seen in adenocarcinomas from other sites, these markers are likely to be of limited value in the differential diagnosis of abdominal adenocarcinomas of uncertain origin.     

The effect of fixatives and paraffin embedding on the histochemical reactivity of a monoclonal antibody against human type IV collagen (JK-199)

A new monoclonal antibody (JK-199) was found to react with basement membranes on paraffin-embedded tissue sections without prior enzyme digestion. JK-199 was shown to react with isolated type IV collagen treated by any of four different fixatives--PLP, 4% formalin, modified Zamboni's (0.2% picric acid, 4% paraformaldehyde in 0.1 M phosphate buffer, pH 7.4) or Bouin's--applied for 6 h at room temperature and incubated at 60 degrees C for 30 min to simulate routine tissue processing. None of the fixatives was able to alter the reactivity of JK-199 with isolated type IV collagen. In the human placenta, specific and intense staining of basement membranes was demonstrated on paraffin sections fixed with any of the four fixatives. In human skin, basement membranes were fully demonstrated on paraffin sections fixed by PLP fixative or by 4% formalin, but only partially on sections fixed by picric acid-containing fixatives. Optimal results, i.e., with the least non-specific or incomplete staining, were obtained on PLP-fixed paraffin-embedded tissues. In PLP-fixed paraffin sections of the kidney, skeletal muscle, and small intestine, all basement membranes were stained intensely by this antibody (JK-199) at the expected locations. The results indicate that JK-199 may be widely applicable for the analysis of basement membrane kinetics, including developmental processes or pathological conditions.     

An Immunohistochemical Study of Cytokeratin and Vimentin in Benign and Malignant Thyroid Lesions

Intermediate filaments in benign and malignant thyroid lesions were immunohistochemically studied using polyclonal and monoclonal anti-cytokeratin (CK), and monoclonal anti-vimentin antibodies. Antigenicity of CK and vimentin was almost completely destroyed during formalin fixation in normal thyroid and all thyroid lesions except for some cases of papillary and squamous cell carcinoma, although the latter showed negative immunostaining with anti-vimentin antibody. In sections fixed with Carnoy's fixative, most cases of papillary carcinoma showed an intense reaction product for polyclonal anti-CK, monoclonal anti-CK-7, CK-19 and anti-vimentin antibodies. The reaction product for anti-CK antibodies was located mainly in the apical cytoplasm and that for anti-vimentin antibody in the basal cytoplasm. However antigenicity was still destroyed by the fixative in many specimens of normal thyroid, benign thyroid lesions and follicular carcinoma. In frozen sections, all specimens showed preserved antigenicity for both antigens with an intense reaction product in papillary carcinoma, but this was weaker in normal thyroid, benign thyroid lesions and follicular carcinoma. Therefore, follicular cells under normal and pathological conditions contain intermediate filaments of CK and vimentin in their cytoplasm and co-expression of the antigens is significantly increased in papillary carcinoma.     

抗人结肠癌单克隆抗体MC_6的制备及其相应抗原的免疫组化定位研究

本研究利用手术中取得的新鲜结肠癌组织免疫Balb/c小鼠。制得5株能持续、稳定分泌抗体的杂交瘤细胞系。其中HC6株杂交瘤细胞经过180天连续培养，单克隆抗体MC6分泌稳定，选择性强，效价高。免疫组化检测发现，MC6相应抗原在结肠癌组织及结肠癌细胞系高度表达（90％～100％），显著高于其它癌组织，癌旁和正常粘膜及癌细胞系（0％～44．4％）；中度以上染色者占阳性者总数80％以上，主要分布于细胞膜上，且除癌细胞膜和胞浆呈阳性反应外，腺腔内粘液亦可见不同程度着色。表明MC6相应抗原是一种在结肠癌细胞膜上占优势的抗原，并可脱落至腺腔。此单克隆抗体的成功研制为发现新的结肠癌生化标志，为结肠癌早期诊断及术后病情监测提供了可能性。     

An immunohistochemical study of cytokeratin and vimentin in benign and malignant thyroid lesions

Intermediate filaments in benign and malignant thyroid lesions were immunohistochemically studied using polyclonal and monoclonal anti-cytokeratin (CK), and monoclonal anti-vimentin antibodies. Antigenicity of CK and vimentin was almost completely destroyed during formalin fixation in normal thyroid and all thyroid lesions except for some cases of papillary and squamous cell carcinoma, although the latter showed negative immunostaining with anti-vimentin antibody. In sections fixed with Carnoy's fixative, most cases of papillary carcinoma showed an intense reaction product for polyclonal anti-CK, monoclonal anti-CK-7, CK-19 and anti-vimentin antibodies. The reaction product for anti-CK antibodies was located mainly in the apical cytoplasm and that for anti-vimentin antibody in the basal cytoplasm. However antigenicity was still destroyed by the fixative in many specimens of normal thyroid, benign thyroid lesions and follicular carcinoma. In frozen sections, all specimens showed preserved antigenicity for both antigens with an intense reaction product in papillary carcinoma, but this was weaker in normal thyroid, benign thyroid lesions and follicular carcinoma. Therefore, follicular cells under normal and pathological conditions contain intermediate filaments of CK and vimentin in their cytoplasm and co-expression of the antigens is significantly increased in papillary carcinoma.     

Differential expression of carcinoembryonic antigens and non cross-reacting antigens in the human thymus. Analysis on frozen sections and cultured epithelial cells using monoclonal antibodies

The organization of epithelial cells in distinct areas of the thymus appears important for understanding the pathways of T-cell differentiation. The presence of carcinoembryonic antigen (CEA) was investigated on sections of human thymus and in cultures of thymic epithelial cells through use of monoclonal antibodies (Mab) discriminating CEA and 2 non cross-reacting antigens (NCA 55 and NCA 95). All together, 5 monoclonal antibodies were used. The Mab 35 and 73 recognized exclusively a specific CEA antigenic determinant, whereas Mab 47, 192 and 202 were also reactive with CEA cross-reacting antigens. By immunofluorescence or the immunoperoxidase technique, staining of CEA was restricted essentially to Hassall's corpuscles and a few adjacent epithelial cells on thymic sections; this pattern was similar to distribution of Ca 19-9 antigen. Additionally, the 47, 192 and 202 antibodies were reactive with a keratin-negative subset mainly located in the cortex. Furthermore, a subset of keratin-positive cells bearing CEA molecules was observed in thymic epithelial cell cultures. Positive cells comprised less than 3% with Mab 35 and 73, and reached up to 12% with Mab 47, 192 and 202. By flow cytometry analysis, staining intensity varied with the epitope; it was much weaker with Mab 35, 47 and 73 than with Mab 192 and 202. The CEA content in culture supernatants was inversely correlated to the number of CEA positive cells. Thus, CEA could be considered as a marker of a late maturation stage of medullary epithelial cells culminating in Hassall's corpuscles and could contribute to delineating the heterogeneity of thymic epithelial cells.