Cell surface glycoproteins of rabbit lymphocytes: characterization with monoclonal antibodies

The structural characteristics of antigens recognized by a panel of monoclonal antibodies prepared against a rabbit T-lymphocyte cell line have been investigated. Those antigens which could be isolated using immunoadsorbents prepared from the monoclonal antibodies had mol. wts of 42,000, 90,000 and 120,000. The 42,000 mol. wt molecule is similar or identical to a rabbit class I major histocompatibility complex antigen and its characterization has been reported elsewhere. Three different 90,000 mol. wt proteins can be distinguished by their reactivity with lectins and by sequential immunoprecipitation. The 120,000 mol. wt protein is a very abundant surface glycoprotein that appears to be a specific marker for T-cells in the rabbit. It is the immunodominant antigen in a lentil lectin bound glycoprotein pool. Over half of the antibodies were directed against this antigen. All antigens detected by the panel of monoclonal antibodies have been detected on normal lymphoid cells.     

Large-scale purification of murine I-Ak and I-Ek antigens and characterization of the purified proteins

Detailed analysis of the role of la antigens in T-cell activation and of the structural characteristics of these molecules will require isolation of relatively large amounts of these antigens in serologically active form. We have purified murine Ia antigens on a large scale by affinity chromatography using monoclonal antibodies coupled to Sepharose 4B. Both I-A^k and I-E^k were isolated by sequential passage of cell lysate over columns prepared using specific monoclonal antibodies. Elution of the bound antigens required high pH (11–12) but, nonetheless, the purified material was 50–75% serologically active. Using LPS-stimulated spleen cells or B-lymphocyte tumor cells as starting material, 0.5 mg of each antigen can be readily purified. Based on antigen yields, it can be estimated that normal B-cells have about the same surface density of Class I and Class II MHC antigens. LPS blasts, in contrast, have normal levels of Class I antigen but 3–5 times higher levels of Class II antigens. We have now purified I-A1' and I-E1' from a number of different cell sources and have noted differences in both the mol. wts of the α- and β-chains and in their apparent associations with cytoskeletal components. Proteins having the same apparent mol. wts as actin and myosin co-purify with both I-A^k and I-E^k antigens from various sources. These proteins do not co-purify with H-2K and D molecules obtained by similar methods, suggesting that Ia antigens may specifically interact with cytoskeletal elements.     

Further comparative studies on chemical properties of carcinoembryonic antigen in tumor tissues and closely related antigens in adult feces and meconium

The chemical structure of carcinoembryonic antigen (CEA) and two closely related antigens, normal fecal antigen-2 (NFA-2) in normal adult feces and nonspecific cross-reacting antigen-2 (NCA-2) in the meconium, were further analyzed comparatively. The NH2-terminal amino acid sequence of NCA-2 was newly determined to position 18 and found to be identical to that so far determined for CEA- and NFA-2. After proteolytic digestion with chymotrypsin or protease V8, the digests of these antigens showed two groups of fragments upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. One consisted of the sharply banded fragments which were identical in all antigens and stained only with Coomassie brilliant blue (CBB) (five bands in the range 2500-10,000 daltons for chymotrypsin and 11 bands in the range 8000-35,000 daltons for protease V8, respectively), and the other consisted of the dispersed fragments which had variable mol. wts in the range 10,000-100,000 and were stainable with both CBB and periodic acid-Schiff reagent. Elution profiles of CEA, NFA-2, and NCA-2 from lectin columns, especially from concanavalin A-Sepharose columns, suggested some differences in oligosaccharide chains between them. These results indicate that the fundamental chemical structure of these antigens seems to be very similar to one another and is divided into two parts; an homologous portion(s) which is common to all three antigens and contains no sialylated sugar components, and a heterogeneous portion(s) which is variable among these antigens and contains sialylated sugar components.     

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.     

Epitope mapping of the carcinoembryonic antigen with various related recombinant proteins expressed in Chinese hamster ovary cells and 25 distinct monoclonal antibodies.

Antigenic epitopes of carcinoembryonic antigen (CEA) and non-specific cross-reacting antigen (NCA) were analysed in relation to their domain structures [domains N, I (A1-B1), II (A2-B2), III (A3-B3) and M for CEA and domains N, I (A1-B1), and M for NCA]. We reconstructed cDNAs for CEA-N, CEA-N-I, CEA-N-I-II, CEA-N-I-II-III-M (CEA-whole), NCA-N, NCA-N-I and NCA-N-I-M (NCA-whole), which were expressed in Chinese Hamster Ovary (CHO) cells. The recombinant proteins were purified by immunoadsorption and gel filtration. Their mol. wts judged from Western blotting were 17,000-26,000 for CEA-N, 70,000 for CEA-N-I, 150,000 for CEA-N-I-II, 165,000 for s-CEA-whole which was spontaneously released from cells into culture medium, 180,000 for p-CEA-whole which was solubilized with phosphatidylinositol specific phospholipase C (PI-PLC) from cells, 18,000-25,000 for NCA-N, 63,000 for NCA-N-I, and 96,000 for p-NCA-whole which was solubilized with PI-PLC from cells. The divergence of the observed mol. wts from those calculated from cDNA sequences seems to indicate that these recombinant proteins are highly N-glycosylated. By enzyme immunoassays, the immunoreactivities of the purified recombinant proteins were tested with 25 distinct anti-CEA monoclonal antibodies (MAbs), each representative of 25 different subgroups within five groups (Groups 1-5) previously classified by us in terms of the reactivity with CEA and CEA-related antigens. Twenty-one MAbs previously shown to react with different protein epitopes of the CEA molecule allow to define six groups (A-F) of epitopes according to their expression by different domains of the CEA and NCA molecules. Among four epitopes common to CEA and NCA, two were found to be present on domain N (Group A) and two on domain I (Group B). Among 15 epitopes absent from NCA but expressed by CEA and normal fecal antigens (NFAs), four were on domain N (Group C), five on domain I (Group D) and six on domain II (Group E). Two epitopes were previously described as "CEA distinctive", because they were recognized by MAbs reacting with CEA but not with the NFAs. These two epitopes (Group F) were found to be expressed by p-CEA-whole but not by s-CEA-whole. The latter results suggest that the Group F epitopes are located on a part of the domain III close to the anchoring device of the CEA molecule.(ABSTRACT TRUNCATED AT 400 WORDS)     

Carcinoembryonic Antigen and Nonspecific Cross-reacting Antigen in Medullary Carcinoma of the Thyroid

Carcinoembryonic antigen (CEA) and nonspecific cross-reacting antigen (NCA) were studied immunohisto-chemically 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.     

Identification and partial characterization of the unglycosylated peptide of carcinoembryonic antigen synthesized by human tumor cell lines in the presence of tunicamycin

Unglycosylated peptide backbones of carcinoembryonic antigen (CEA) synthesized by human tumor cell lines in the presence of tunicamycin were identified and analyzed by SDS-polyacrylamide gel electrophoresis. Three tumor cell lines, QGP-1 (pancreas), FCC-1 (colon) and KNS-62 (lung) were found to produce CEA molecules of 180,000-190,000 mol. wts labeled with both [3H]leucine and [14C]glucosamine under conventional culture conditions. In contrast, in the presence of tunicamycin, the native CEA molecules disappeared, and a new component that was precipitated with anti-CEA antibodies and labeled only with [3H]leucine but not with [14C]glucosamine was identified in each cell line. Monoclonal antibodies each directed to different major antigenic determinants on the native CEA molecules also reacted with this unglycosylated peptide. The apparent mol. wts of the naked CEA peptides from QGP-1 and FCC-1 were equally about 78,000, whereas that from KNS-62 was somewhat larger than the other two, suggesting some differences in the peptide structure of the CEA molecules.     

A glycoprotein of molecular weight 85,000 on human cells of B-lineage: detection with a family of monoclonal antibodies

Immunization of BALB/c mice with glycoproteins purified from a detergent extract of human chronic lymphocytic leukemia (CLL) cells by affinity to Lens culinaris lectin led to the production of several monoclonal antibodies with similar reactivity. One of the antibodies, 50B4, was purified and the corresponding antigen was isolated from a B-lymphoblastoid cell line extract by affinity chromatography to the 50B4-IgG immunoadsorbent. Co-purification of the antigenic activities associated with five other monoclonal antibodies was achieved. Purified and radiolabelled 50B4 antigen could be specifically immunoprecipitated not only by 50B4 but also by the other five antibodies. SDS-PAGE analysis revealed that all antibodies precipitated the same component, a polypeptide chain of apparent mol. wt 85,000 under reducing conditions. Competitive-binding studies between the purified antibodies indicated the presence of two distinct epitopes on the antigen. The epitopes, each recognized by three different antibodies, were equally accessible on the cell surface of either a B-CLL (3 X 10(5) molecules/cell), a B-lymphoblastoid cell line (11 X 10(5) molecules/cell) or two acute lymphocytic leukemia (ALL) cell lines of pre-B phenotype (5 X 10(5) and 0.8 X 10(5) molecules/cell respectively). Although the antigens purified from the strongly positive ALL cell line gave a gel pattern identical to that of the B-lymphoblastoid cell line, the antigens purified from the B-CLL extract were resolved into two distinct glycosylated polypeptides of mol. wts 85,000 and 77,000 under reducing conditions. The distribution of the antigen(s) is not restricted to cells of the B-lineage as mature T-cells and a variety of non-hematopoietic cell types express both epitopes of the antigen(s).     

Characterization of monoclonal antibodies to carcinoembryonic antigen with increased tumor specificity

Nine monoclonal antibodies reacting with carcinoembryonic antigen (CEA) were produced after immunization of mice with either purified CEA or a CEA-producing human cell line. Their specificities were assessed by immunohistochemistry on tissue sections of neoplastic and nonneoplastic lesions. These monoclonal antibodies have different patterns of tissue reactivity. Two of them, D14 and B18, were found to have a high degree of specificity for colonic carcinoma and did not react with formalin-fixed paraffin-embedded sections of normal colon with standardized staining conditions. Most cases of noncolonic adenocarcinomas and normal epithelial structures were not stained by these two monoclonal antibodies. The specificity of the monoclonal antibodies was further investigated immunochemically using intact, reduced, and alkylated or chemically fragmented CEA. Liquid phase radioimmunoassays and antibody competition immunoenzymatic assays confirmed that the antibodies recognize different epitopes of CEA. These data support the concept of CEA heterogeneity and the reactivity of the D14 and B18 monoclonal antibodies with colonic adenocarcinomas indicates that they are useful immunohistochemical probes.     

Monoclonal antibody against carcinoembryonic antigen (CEA) identifies two new forms of crossreacting antigens of molecular weight 90,000 and 160,000 in normal granulocytes

Two new forms of non-specific crossreacting antigens (NCAs) were identified in the Nonidet P40 (NP-40) extracts of normal granulocytes by precipitation with the monoclonal antibody (MAb) 192 directed against carcinoembryonic antigen (CEA) and already known to crossreact with the perchloric acid soluble NCA-55. The NP-40 soluble NCAs recognized by MAb 192 have apparent mol. wts of 90,000 and 160,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Both NCAs appear to consist of a single monomeric polypeptide chain, since they have the same electrophoretic mobility in SDS-PAGE under reduced and non-reduced conditions. When granulocytes were extracted with perchloric acid instead of NP-40, only the 55,000 mol. wt antigen, corresponding to the previously described NCA-55, was precipitated by MAb 192. Furthermore, it was shown that NCA-55 is not a degradation product of NCA-90 or NCA-160 due to the perchloric acid treatment because exposure to perchloric acid of NCA preparations purified from NP-40 extracts did not change their apparent mol. wts in SDS-PAGE. It was also shown that NCA-160 is not a granulocytic form of CEA because it was not precipitated by the MAb 35 reacting exclusively with CEA. Immunocytochemical studies of granulocytes and macrophages showed that MAb 192 stained both types of cells whereas MAb 47 stained only the granulocytes and MAb 35 none of these cells. In granulocytes both MAbs reacted with antigens associated with granules and also present at the periphery of the nucleus as well as in the Golgi apparatus. The NCA-90 identified by MAb 192 was found by sequential immunodepletion to be antigenically distinct from the NCA-95 precipitated by MAb 47. The epitope recognized by MAb 192 on CEA and NCA molecules appears to be on the peptidic moiety because the antigens deglycosylated by the enzyme Endo F were still precipitated by this MAb. Taken together, the results indicate that MAb 192 identifies two novel forms of NCA (NCA-90 and NCA-160) in NP-40 extracts of granulocytes, which are distinct from CEA and the previously described NCA-55 and NCA-95 identified by MAbs 192 and 47, respectively, in perchloric acid extracts of granulocytes.     

Identification of Ia glycoproteins in rat thymus and purification from rat spleen.

A fraction of la-like glycoproteins was prepared from rat thymocytes by lentil lectin affinity chromatography and gel filtration in deoxycholate. Spleen cells from mice immunized with this preparation were fused with myeloma cells to produce antibody-secreting hybrid cell lines. Antibody from four lines called MRC OX, 3, 4, 5, 6 reacted with the la-like glycoproteins, and MRC OX 3 antibody recognized an antigenie determinant polymorphic in the rat. All four antibodies also bound to mouse spleen cells and all detected polymorphisms. Studies on recombinant mouse strains suggest that the determinants are coded by the I-A subregion of the H-2 complex. MRC OX 3 correlates with Ia specificity 9, while MRC OX 4, 5, 6 correlate with specificity 17 or 18. MRC OX 4 monoclonal antibody was used for affinity chromatography to purify Ia glycoproteins from rat spleen. The rat Ia glycoprotein complex was composed of two noncovalently linked polypeptide chains of apparent mol. wt. (unreduced) 30 000 and 24 000 as determined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The purified Ia glycoprotein partially inhibited the binding to thoracic duct lymphocytes of an alloantiserum which detects Ia antigens linked to the major histocompatibility complex. The monoclonal anti-la antibodies bound to the majority of peripheral B lymphocytes and 18% of thymocytes, but did not significantly bind to peripheral T lymphocytes. There were on average 150000 molecules of Ia glycoprotein per la-positive B lymphocyte, and 45 000 molecules per la-positive thymocyte. From the same fusion, another cell line was prepared called MRC OX 2 which secretes monoclonal antibody to a previously undefined thymus glycoprotein of apparent mol. wt. 60000. Preliminary studies showed that the antigen was expressed on all thymocytes and on peripheral B lymphocytes in smaller amounts. It was also present in brain, but not liver or kidney homogenate.     

Production of monoclonal antibody SP-21 to colon-ovarian tumor antigen, COTA

An IgG monoclonal antibody, SP-21, directed against colon-ovarian tumor antigen, COTA, is reported. The antibody had no reactivity with CEA, normal colonic mucin, CSAp, ABO blood group antigens, or with normal human lung, liver, spleen, kidney, plasma and saliva in studies using the enzyme-linked immunoassay method (ELISA). Immunoperoxidase staining of colon, lung, kidney, and prostate cancer tissues and benign and inflammatory colon disease tissues revealed a specificity identical to that of the polyclonal (goat) anti-COTA antibodies.     

The molecular basis of T helper cell function--I. Allotype- and MHC-linked determinants on antigen-specific, H-2-restricted T cell lines, hybridomas and lymphomas

A T-cell hybridoma clone, which produces antigen-specific helper factors and a T-cell lymphoma clone which produces non-specific helper factors was used to study the expression of T-cell allotypes and Ia antigens. Use was made of rabbit antisera against isolated T-cell receptor material and of monoclonal mouse antibodies against isolated rat Ia antigen. The rabbit antisera detected endogenously produced determinants both on the membrane and on intracellular polypeptides of these cells. The monoclonal mouse anti-rat-Ia antibodies detected polymorphic determinants on mouse Ia antigens and reacted with endogenously produced molecules on the membrane and on intracellular molecules of the hybridoma and lymphoma cells. The molecules carrying Tcr allotypes were single-chain polypeptides with mol. wts of 60,000-70,000 and the molecules carrying Ia-like antigenic determinants were single-chain polypeptides with mol. wts of 40,000-50,000. Thus T-cell allotypes and Ia antigens were found on separate polypeptide chains. The role and genetic localization of allotype-like and Ia-like molecules in T-cell products is discussed.     

Unusual expression of HLA molecules at the surface of murine cells transfected with HLA-B7 or HLA-A11 genes

The HLA-B7 and HLA-A11 molecules expressed on murine transfectants have been analysed by one- and two-dimensional polyacrylamide gel electrophoresis (PAGE). Two different murine cells, L and P815-HTR have been compared, because it has been previously established that P815 transfectants were much more sensitive to human cytolytic cells than L transfectants. Three kinds of HLA molecules were present on these cells: (1) normal HLA molecules with 2D-PAGE profiles identical to those of the molecules isolated from human cells; (2) HLA molecules of usual size but with more various charges than HLA molecules detected on human cells. This heterogeneity was constantly found with cells expressing HLA-B7 or -A11 antigens, both in L and in P815 transfectants, including several clones. These forms were detected by anti-HLA monoclonal antibodies and by antipeptide (from HLA-B7) antibodies; (3) other unusual products corresponding to shorter heavy chains: molecules of various mol. wts and charges were detected in HLA-B7 but not in HLA-A11 transfectants. They were observed using antipeptide sera but were not seen with anti-HLA monoclonal antibodies. These products were possibly related to the DNA used for transfection and it cannot be excluded that such abnormalities only detectable by antipeptide sera would exist in other transfectants. The functional discrepancies between P815 and L transfectants cannot be clearly explained by these biochemical results.     

Catalase,a specific antigen in the feces of human subjects infected with Helicobacter pylori

Recently, we reported the production of three new monoclonal antibodies with high specificity for a Helicobacter pylori antigen suitable for diagnosis of H. pylori infection. The aim of the present study was to identify the antigen recognized by these monoclonal antibodies concerning both H. pylori and the feces of human subjects infected with H. pylori. The cellular antigen was purified from an H. pylori cell extract by immunoaffinity column chromatography with the monoclonal antibody as a ligand. The amino-terminal amino acid sequences (eight residues) of the purified antigen and H. pylori catalase were the same. The molecular weights of native and subunit, specific catalase activity, and UV and visible spectra of the purified antigen were in good agreement with those of H. pylori catalase. The human fecal antigens were purified from two fecal samples of two H. pylori-positive subjects by ammonium sulfate precipitation, CM-Sephadex C(50) chromatography, and the same immunoaffinity chromatography used for the H. pylori cellular antigen. The fecal antigens had catalase activity. The amino-terminal amino acid sequences (five residues) of the human fecal antigen and H. pylori catalase were the same. The monoclonal antibodies reacted with the native cellular antigen, but did not react with the denatured antigen, human catalase, and bovine catalase. The results show that the target antigen of the monoclonal antibodies is native H. pylori catalase and that the monoclonal antibodies are able to specifically detect the antigen, which exists in an intact form, retaining the catalase activity in human feces.     

High levels of antibodies to streptococcal cell membrane antigens specifically bound to monoclonal antibodies in acute poststreptococcal glomerulonephritis

We produced 15 immunoglobulin G class monoclonal antibodies against antigens of the streptococcal cell membrane (SCM) of Streptococcus pyogenes (T type 12, Tanaka strain) and determined the levels in human sera of antibodies against Triton-X-extracted antigens specifically bound to each of these 15 monoclonal antibodies by enzyme-linked immunosorbent assay. Sample sera were obtained from 10 normal controls (group 1), 10 patients with streptococcal pharyngitis without sequelae (group 2), and 8 patients with acute poststreptococcal glomerulonephritis (APSGN) (group 3). Anti-streptolysin O (ASO) titers of the sera increased in the order of groups 1, 2, and 3. There was no relationship between ASO titer and the level of anti-SCM antibodies, and there was no significant difference in the level of anti-SCM antibodies determined with each of the 15 monoclonal antibodies between group 1 and group 2 sera. Group 3 sera had higher levels of antibodies to SCM antigens specifically bound to each of 14 of these 15 monoclonal antibodies than group 1 or group 2 sera did. Of these 14 monoclonal antibodies, 9 reacted with the four SCM antigens separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrophoretically transferred to a nitrocellulose sheet. These results suggest that high levels of antibodies to SCM antigens are related to the development of APSGN and that the systemic immune response to SCM antigens is involved in the pathogenesis of APSGN.     

Determination of human antibodies to specific antigens of cytomegalovirus using an antigen capture immunoassay

The antigen capture immunoassay which is described herein is based on the binding of specific antigens of cytomegalovirus (CMV) by monoclonal antibodies bound to a solid phase. The specificity of the binding was demonstrated by the analysis of antigens labelled with [35S]methionine and captured by the bound monoclonal antibodies. These specific antigens are recognized in turn by specific anti-cytomegalovirus antibodies in human sera. The immunoassay permits quantitation of these specific anti-cytomegalovirus antibodies and should facilitate both qualitative and quantitative comparisons of the antibodies against specific CMV antigens in different individuals.     

基于压电谐振检测技术的癌胚抗原免疫传感器的实验研究

为了建立一种新型压电石英晶体癌胚抗原(CEA)免疫传感器,传感器检测池用AT切向、基频10 MH z的石英晶体通过金属夹具和乳胶套圈固定组成,采用巯基化方法把抗人CEA单克隆抗体固定在金膜电极表面制成抗体敏感膜,构成的压电CEA免疫传感器应用于临床检测。实验结果显示:构建的压电CEA免疫传感器对CEA的响应特性良好,其线性检测范围为1.56~50.00 ng/m l,甲胎蛋白(AFP)、前列腺特异抗原(PSA)、人绒毛膜促性腺激素(hCG)等对CEA的检测基本无干扰;传感器可再生后重复使用5次;50例临床标本检测结果与放射免疫检测法符合(P>0.05),两种方法的相关系数为0.90。研制的压电CEA免疫传感器具有灵敏度高、特异性好、不需标记、操作简单、省时、能实时在线检测和重复使用等优点,对比分析表明其检测结果准确、可靠,可用于临床检验。     

Monoclonal antibodies to human malignant mesothelioma

Murine monoclonal antibodies were used to identify tumor-cell membrane antigens on a new human mesothelioma cell line. Hybridomas were constructed by fusing SP2/0 mouse myeloma cells with spleen cells from Balb/C mice immunized by the human mesothelioma cell line MT-1. Hybridoma antibody was detected in 55/672 microculture wells that reacted to these MT-1 tumor cells by an indirect¹²⁵I-protein A binding assay. Six cultures produced antibody binding selectively to the MT-1 tumor cells but not to a human lymphoblastoid cell line. These six hybridomas were cloned: three were IgG and three were IgM antibodies. One monoclonal, MAb 45, reacted with 4 of 7 human mesothelioma cell lines but with only 1 of 11 carcinomas, 1 of 3 sarcomas, 4 of 11 melanomas, and 0 of 5 lymphoid lines. The other five monoclonals had a much broader cross-reactivity. Using an immunoperoxidase technique, MAb 45 bound to mixed-type malignant mesotheliomas but not to normal lung and pleura. The specificity of MAb 45 for diffuse mesotheliomas and the low cross-reactivity with carcinomas and normal adjacent tissues suggest that this monoclonal may be clinically useful.     

Purification and characterization of a 50,000 mol. wt glycoprotein antigen, and localization of determinants involved in cross-reactivity with carcinoembryonic antigen

A 50,000 mol. wt glycoprotein antigen (50 k) was purified from metastatic colon tumor. The initial purification was monitored by cross-reactivity of the antigen with an unabsorbed antiserum against carcinoembryonic antigen (CEA, Mr 180,000). Six mg of antigen was obtained from 250 g of tissue, with a recovery of 14% and a relative purification of 143-fold. The amino acid composition of 50 k was similar to that of CEA. The carbohydrate content, primarily glucosamine and mannose, totaled about 25%. Immunodiffusion showed that 50 k lacked some of the CEA epitopes, and that normal spleen contained an antigen identical to 50 k. Radioimmunoassays showed that the high avidity anti-CEA antibodies in the unabsorbed antiserum were mainly cross-reactive with 50 k, probably via a similar but not identical antigenic site. The immunochemical properties of 50 k thus correspond to those of the non-specific cross-reacting antigen (NCA). The molecular size and carbohydrate composition reported for various NCA-like antigens have differed, so identity of 50 k an NCA cannot be established on this basis. Immunoreactive fragments of 50 k were prepared by digestion with each of three different proteolytic enzymes, and were purified by high performance liquid chromatography (HPLC). A polypeptide of 20,000-30,000 mol. wt containing about half of the 50 k determinants, was recovered in each case. Experiments with mixtures showed that the three purified fragments all contained the same subset of antigenic determinants. The fragment-localized subset represented most, if not all of the 50 k determinants involved in CEA cross-reactivity. Similarly, a CEA fragment was shown to contain essentially all of the CEA determinants involved in 50 k cross-reactivity. The fragments of 50 k and CEA were quite resistant to further proteolytic digestion, and comparison of a CEA fragment with a 50 k fragment by partial acid hydrolysis and HPLC peptide mapping failed to reveal structural homology to account for the cross-reactivity.