Glycoprotein PAS-0 from the milk fat globule membrane carries antigenic determinants for epithelial membrane antigen

Expression of MUC-1 glycoprotein in plasma cells, follicular dendritic cells, myofibroblasts and perineurial cells: immunohistochemical analysis using three monoclonal antibodies

Normal and malignant plasma cells (PC), follicular dendritic cells (FDC), myofibroblasts (MFB) and perineurial cells (PNC) were investigated for the expression of MUC-1 glycoprotein (MUC-1gp) by immunohistochemical and immunoelectron microscopic techniques using monoclonal antibodies E29, 115D8, DF3 and a combination of the three. MUC-1 glycoprotein-positive PC detected by the combined antibodies were frequently seen in a variety of pathological lesions tested, including chronic cervicitis, chronic synovitis, Hodgkin's disease, allergic rhinitis and sinusitis, tuberculous lymphadenitis, foreign body granuloma, multiple myeloma, and chronic tonsillitis. In the lesions containing MUC-1gp-positive PC, the infiltration of immunoglobulin (Ig) E PC and/or IgE-bound mast cells was significantly increased, but MUC-1gp-positive PC did not contain any specific immunoglobulin heavy or light chains. The findings suggest that the expression of MUC-1 gp in PC, although not restricted to IgE-class cells, may be induced in an allergic status. Plasma cells and PNC mainly reacted with the antibodies E29 and 115D8, while FDC and MFB were principally reactive with the antibody DF3. In some cases of multiple myeloma, the neoplastic PC were predominantly immunoreactive with DF3. The results indicate: (i) the epitopic variability of MUC-1gp molecules expressed on the non-epithelial cells; and (ii) the epitopic alterations during malignant transformation. It should also be noted that the expression of MUC-1gp in the non-epithelial cells represents a pitfall in histopathological diagnosis.

Use of peanut lectin and rat mammary stem cell lines to identify a cellular differentiation pathway for the alveolar cell in the rat mammary gland

The presence of the carbohydrate receptor for PNL has been used to identify the previously described morphological types of epithelial cell produced as the stem cell line rat mammary 25 (Rama 25) differentiates to casein secretory alveolar-like cells in vitro. Thus when cultures of the epithelial stem cell line Rama 25 are treated with neuraminidase, fluorescently-conjugated PNL fails to stain cuboidal cells, stains weakly grey cells, and stains strongly the surface of dark cells. When superconfluent cultures of Rama 25 are treated with dimethyl sulfoxide or retinoic acid and prolactin, estradiol, hydrocortisone, and insulin to induce differentiation to alveolar cells, PNL stains strongly the untreated surfaces of droplet cells and casein-secreting vacuolated cells. PNL-staining of the derivative cell lines with truncated cellular pathways, and quantitative binding of [125I]-labeled PNL to the cultured cells are consistent with this cellular staining pattern. The presence of the carbohydrate receptor for peanut lectin (PNL) has also been used to identify specific epithelial cell types in different mammary structures of the developing rat mammary gland, as they differentiate to casein secretory alveolar cells in vivo. Thus when different structures of the developing rat mammary gland are treated with neuraminidase, peroxidase-conjugated PNL fails to stain histochemically the majority of epithelial cells in ducts, stains the cytoplasm of the majority of epithelial cells in terminal end-buds (TEBs), and stains strongly the luminal surfaces of the majority of epithelial cells in alveolar buds (ABs). PNL also stains the untreated luminal surfaces of alveolar cells, whether or not the cells can be stained with a monoclonal antibody to rat beta-casein. Stimulation of mammary differentiation by an analogue of ethyl retinoate or by perphenazine causes cells in end-buds to bind PNL without the necessity for their desialylation similar to that seen in casein secretory alveoli of lactating rats. In conclusion the different interconverting cell types of Rama 25 which form a pathway to casein-secretory cells in vitro are thus equated with recognisable epithelial cell types in vivo. These results suggest that casein-secretory cells in vivo are generated by similar successive interconversions between the major epithelial cell types present in the different mammary structures in the order: ducts, TEBs, ABs, alveoli, and secretory alveoli.

Immunohistochemical and biochemical characterization of the mucin-type tumor associated antigen TAG-12 by monoclonal antibody 7A9

The reactivity of monoclonal antibody 7A9 with normal and neoplastic human tissues and some biochemical characteristics of the antigen (TAG-12) bound by 7A9 were evaluated. Antibody 7A9 showed broad reactivity with various carcinomas in paraffin sections. High percentages of positive tumor cells, displaying membrane and cytoplasmic staining, were noticed in adenocarcinomas of the breast (83/85), serous cystadenocarcinomas of the ovary (15/16), and lung adenocarcinomas (14/16). TAG-12 antigen was also detectable in normal adult and fetal tissues, but the reactivity of 7A9 was mainly restricted to the luminal surface of epithelial cells. For biochemical analyses, TAG-12 antigen purified from T47-D breast carcinoma cells by lectin affinity chromatography was treated with different glycosidases and proteases and analyzed by immunoblotting with 7A9. The data indicate that the antigen recognized by 7A9 is a heavily sialated mucin-type glycoprotein with a molecular weight of more than 200 KD. Similar to all other antibodies against tumor associated antigens, monoclonal antibody 7A9 is not tumor-specific but displays tissue staining patterns with a high carcinoma-to-normal ratio. The strong reactivity with the majority of tumor cells in several carcinoma types suggests that 7A9 is useful for in vitro and in vivo targeting of those tumors.

Bindings of the lectins Griffonia simplicifolia-1 and pokeweed mitogen mark discrete stages of myoepithelial-like differentiation of cell lines from the rat mammary gland

Individual single-cell-cloned cell lines of the different rat mammary (Rama) cell types have been tested for their ability to bind the lectins Griffonia simplicifolia-1 (GS-1) and pokeweed mitogen (PWM) using fluorescent, histochemical, and radioactive assays. Myoepithelial-like cell lines isolated from neonatal rat mammary glands and from nonmetastasizing tumors strongly bind GS-1 and PWM, whereas the corresponding epithelial and fibroblastic cell lines do not. When the epithelial cell lines are grown on floating gels of polymerised rat tail collagen, the basally situated or peripheral cells are stained strongly with peroxidase-conjugated lectins, whereas the apically or luminally situated cells are unstained. The capacity of cell lines intermediate in morphology between epithelial and myoepithelial-like cells to bind to GS-1 is as follows: Rama 25 epithelial less than Rama 25-12 less than Rama 25-11 less than Rama 25-14 less than Rama 29 myoepithelial-like cells, the same order as for other markers of myoepithelial cells. Conjugated PWM, however, binds only to the myoepithelial-like cell lines. Treatment of Rama 25 epithelial cells with agents that disrupt microtubules accelerates their conversion to elongated, myoepithelial-like cells in culture. The binding of cells to GS-1 is observed prior to, and that to PWM after, the major morphological change. It is suggested that the stepwise appearances of carbohydrate receptors for GS-1 and PWM mark discrete stages in the differentiation of epithelial to myoepithelial-like cells in culture, in the same way that they mark similar differentiation stages in ductal development in mammary glands of prepubertal rats.

Analysis of the tumour-associated antigen TAG-12 by monoclonal antibody 7A9 in normal, benign and malignant mammary tissues

A monoclonal antibody 7A9 was raised against the tumour-associated glycoprotein TAG-12 purified from T47-D breast carcinoma cells. In immunoblots from cytosol of T47-D cells and from sera of breast cancer patients, antibody 7A9 detects the high molecular weight mucin-like TAG-12 antigen. A series of paraffin sections of normal, benign and malignant mammary tissues have been studied with monoclonal antibody 7A9 and the immunoalkaline phosphatase method. In resting gland, proliferating gland and fibroadenoma ducts, reactivity of 7A9 was mainly restricted to luminal membranes of epithelial cells and secretions. 77/79 primary breast carcinomas including ductal, lobular and various other carcinoma types showed cytoplasmic and/or membrane-associated staining with 7A9 in most tumour cells. Metastases (31/31) from different sites were also positive. Strong immunoreactivity with single tumour cells was noted in cytological preparations from freshly resected breast cancer tissue. Thus, monoclonal antibody 7A9 seems to be very useful for the targeting of breast carcinoma cells.

Human tumor and normal tissue reactivity of the anti-(breast cancer) monoclonal antibody BA-Br-3 and its similarity to the anti-(epithelial membrane antigen) monoclonal antibody E29

A mouse monoclonal antibody (BA-Br-3) raised against the breast carcinoma cell line CAMA-1 was previously shown to react with a greater than or equal to 300-kDa globule-like glycoprotein from human milk fat also expressed in the cytoplasm and on the surface of human carcinoma cells of different histological types. In this report the reactivity of this mAb with a large number of normal and malignant human tissues was analyzed using immunoperoxidase techniques. When tested on sections of both fresh-frozen tissues and formalin-fixed, paraffin-embedded tissues, BA-Br-3 reacted with a formalin-resistant antigenic determinant expressed by normal and malignant epithelial cells. Preferential reactivity was observed at the apical portion of ductal epithelial cells in normal breast and in glandular epithelia distributed in several other organs. Reactivity with mucin-like secretions in the lumina of ducts was also found. BA-Br-3 reacted mostly in heterogenous staining patterns with 88% of 49 breast carcinoma specimens tested, regardless of their histological type or whether they were primary or secondary neoplasms. Testing of epithelial malignant tumors other than breast carcinomas with this antibody showed that 127 of 151 (84%) were also reactive. mAb BA-Br-3 and E29 (a commercially available anti-(epithelial membrane antigen) shared very similar staining patterns and distributions of reactivity with breast and other epithelial tumors. However, BA-Br-3 showed a significantly higher percentage of reactivity with melanoma (33% versus 6%, P = 0.003) and a trend toward a higher percentage of reactivity with sarcoma (55% versus 27%, P greater than 0.05). This antibody, therefore, defines a molecule that is a member of the mucin-like epithelial membrane antigen family. Further studies are warranted to determine its usefulness in antibody-directed cancer diagnosis, prognosis, and immunotherapy.

Critical evaluation of monoclonal antibody staining in breast carcinoma

The immunoperoxidase staining of 84 primary invasive breast carcinomas with four monoclonal antibodies (BRST-1, HMFG1, EMA, B72.3) was evaluated by semiquantitative light microscopical examination and quantitative image analysis. Major differences in the staining of the tumours for each of the monoclonal antibodies was observed. Correlation between monoclonal antibody staining and patient age, survival, histological grade, tumour diameter and cellularity was also carried out. This showed a significant association between histological grade and staining with BRST-1 and EMA.

Monoclonal antibodies reactive with mucin expressed in breast cancer

Three murine monoclonal antibodies (BC1, BC2 and BC3) were developed against human milk fat globule membrane (HMFGM). By immunoperoxidase staining, it was found that the antigenic determinants had a predominant distribution in breast cancer tissue. In addition, the antibodies reacted preferentially with mucin derived from human milk rather than that derived from the breast cancer cell line ZR75; they also recognized polymorphic high molecular weight components (MW greater than or equal to 230,000) in serum and in human milk fat globule membrane. Thus the antibodies appear to react with a component of the family of mucins found in breast cancer and human milk and it appears likely that at least part of each epitope is protein in nature. Antibodies BC1, BC2 and BC3 recognized related but not identical epitopes, and they appear to be co-expressed on the same molecules as 3E1.2-defined antigen (mammary serum antigen, MSA) which is also a member of the family of breast cancer-related mucin. However, the 3E1.2 epitope is distinct and non-cross-reactive with those described for BC1, BC2 and BC3. The BC2 and BC3 defined epitopes were examined for their value in serum assays. Immunoassay was developed with a combination of two antibodies, using antibody BC3 for antigen capture and antibody BC2 or 3E1.2 for antigen detection and gave reasonable sensitivity (approximately 85%) and specificity (approximately 95%) in such serum tests for breast cancer. In a limited study, these tests appeared to complement the MSA test in the detection of breast cancer.

Purification and biochemical characterisation of a novel breast carcinoma associated mucin-like glycoprotein defined by antibody 3E1.2

A member of the high molecular weight glycoproteins of human milk and breast cancer was isolated from the sera, ascites and breast carcinoma tissue of patients with breast cancer using monoclonal antibody 3E1.2. The 3E1.2 defined antigen, termed mammary serum antigen (MSA) was obtained by immunoaffinity chromatography and a solid phase immuno-precipitation technique (SPIT) from serum of patients with metastatic breast cancer. MSA was found to be a high molecular weight glycoprotein with a Mr greater than 300,000 by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and a native Mr approximately 1 x 10(6) by gel filtration chromatography; in accord with the published Mr of other high molecular weight glycoproteins obtained from human milk and breast cancer. A high degree of glycosylation of MSA molecule was shown by its poor staining with Coomassie blue but good staining in a PAS-silver stain. In addition, MSA contained N-acetyl neuraminic acid and N-acetyl glucosamine as indicated by its binding to wheat-germ agglutinin. The epitope defined by antibody 3E1.2 is sensitive to treatment by sodium periodate and neuraminidase, implying that both carbohydrate and sialic acid are required for binding of antibody 3E1.2. Sandwich immunoassays demonstrated that MSA+ molecules are likely to express repeated 3E1.2 defined epitopes. Furthermore, MSA was susceptible to degradation by pronase, subtilisin and proteinase K and gave a different peptide profile from that of the PAS-O glycoprotein of human milk. MSA+ molecules were found to carry epitopes for a number of other monoclonal antibodies which were reactive with the PAS-O glycoprotein. It is suggested that MSA has the same core protein as is recognised by antibody DF3 which has been used to clone the same cDNA as was cloned with antibodies HMFG-1, HMFG-2 and SM-3. However, the epitope detected by the 3E1.2 antibody is either absent or weakly expressed on human milk, human milk-fat globule membrane (HMFGM) or deglycosylated HMFGM--all of which react strongly with various anti-HMFG antibodies. The antibody 3E1.2 thus recognises a unique epitope of the high molecular weight glycoproteins of human milk and breast cancer, being found in cancer tissue, serum and ascitic fluid of patients with breast cancer but weakly expressed or absent in human milk.

Serum level of cryptic tumor antigens in breast cancer patients as determined by two monoclonal antibodies (M85/F36) and its comparison with CA 15-3

An enzyme immunoassay system that measures cryptic epitopes on breast cancer mucinlike antigens (BCM-EIA) was evaluated in a double-blind manner in sera from 58 normal blood donors, 36 sex- and age-matched controls, 36 patients with benign breast diseases, and 47 patients with breast cancer. Two murine monoclonal antibodies, M85 (IgM) as the solid-phase and F36/22 (IgG3) as the probe, were used in the configuration of the assay kit. The assay additionally utilized neuraminidase to remove terminal sialic acid from carbohydrate side-chains to expose cryptic epitopes that were masked in serum specimens. BCM-EIA monoclonal assay from the normal healthy blood donors resulted in 17.34 +/- 7.04 units/ml (mean +/- 1 S.D.) with an upper normal cutoff of 31.4 units/ml. The distributions of serum BCM in the sex- and age-matched controls (17.77 +/- 11.17) and benign breast diseases (14.34 +/- 11.46) were similar to that of normal blood donors. A mean value of 66.04 units/ml and 27.74 units/ml was obtained from breast cancer patients with active disease and without evidence of disease, respectively, a level much greater than those of normals, controls, and benign breast diseases. Simultaneous analysis of CA 15-3, a putative breast tumor marker, in the normal donors and breast cancer patients revealed correlation regression of (CA 15-3) = 0.876 (BCM) + 1.972, r = 0.856; and (CA 15-3) = 0.66 (BCM) + 16.094, r = 0.730, respectively. These data showed that there is a statistically significant correlation of CA 15-3 and BCM in normal blood donors' specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Development and characterization of a syngeneic monoclonal antibody to a rat mammary tumor metastasis-associated mucin-like cell-surface antigen (gp580)

A rat hybridoma producing IgM monoclonal antibody (MAb) GP21:56 was generated with specificity for a high-molecular-weight, mucin-like glycoprotein (gp580) present on highly metastatic 13762NF rat mammary adenocarcinoma cells. The hybridoma was made by fusing rat Y3 Ag1.2.3 myeloma cells with spleen cells from a rat immunized i.d. with purified gp580. The gp580 appeared to be of low immunogenicity in syngeneic F344 rats because a total of 27 fusions were required to produce one hybridoma with specificity for this glycoprotein. Immunoblotting of purified gp580 after electrophoresis in 1% agarose and antibody-binding assays using purified gp580 linked to microtiter plates confirmed that MAb GP21:56 bound specifically to gp580. Other MAbs made against breast mucins were negative for gp580 reactivity. Enzyme-linked immunoabsorbent assays (ELISA) and radiolabelled antibody binding assays demonstrated that MAb GP21:56 bound to 13762NF adenocarcinoma cell lines and clones in relation to their spontaneous metastatic potentials; significantly more MAb GP21:56 bound to highly metastatic MTLn3 cells than to low metastatic MTC cells, and MAb GP21:56 showed little reactivity towards the majority of other cell lines tested, whether of rodent or of human origin. Kinetic binding studies indicated that MAb GP21:56 does not have a high affinity for gp580 but, once bound, it shows high avidity for this sialogalactoprotein. Localization studies using frozen tissue sections of 13762NF tumors indicated that MAb GP21:56 reacts with tumor cells grown in vivo in an analogous manner to in vitro cultured cells. Using immunoperoxidase techniques, less than 50% of the highly metastatic MTLn3 tumor cells were stained, whereas approximately 20% of the intermediate metastatic MTF7 and MTLn2 cells and less than 10% of low metastatic MTC and MTPa cells were stained with MAb GP21:56. The cell-to-cell reactivity was heterogeneous and mainly associated with the tumor-cell surface and extracellular matrix.

Epithelial membrane antigen (EMA) distribution in various biological fluids

Different human biological fluids, namely breast cyst fluids (five), milks (four), sera (five), were submitted to molecular sieving chromatography on Sepharose CL6B. Global protein contents of the eluted fractions were estimated by the Bradford method. Epithelial membrane antigen (EMA) was assayed by two different ELISA techniques using polyclonal and monoclonal antibodies. Various molecular species reacting with EMA (15) were found in the chromatographies with molecular weights ranging from 35 to 1500 kd. But the total amount of antigens detected using polyclonal or monoclonal antibodies was quite similar. Moreover no significant difference was found between the sera from two lactating women and the sera from three women with adenocarcinoma with respect to the molecular distribution of different molecular species of EMA.

Epitope analysis of monoclonal antibody NCRC-11 defined antigen isolated from human ovarian and breast carcinomas

NCRC-11 is an IgM monoclonal antibody which defines an antigen found in most epithelial malignancies. The antigen has previously been shown to be a high mol. wt. glycoprotein (greater than 400,000) and in this study, antigen preparations were isolated by immunoadsorbent chromatography from ovarian mucinous and ovarian serous cyst adenocarcinoma and from breast carcinoma. Other monoclonal antibodies, against products in normal human milk, and antibodies of the Ca series (Bramwell et al., 1985) reacted with all three antigen preparations. Tests involving epitope mapping were performed to probe the relationships of the various epitopes to that defined by the NCRC-11 antibody, and, of note, the three antigen preparations from different tumour sources were remarkably similar with respect to their relative levels of epitope expression and to their topographical distribution of epitopes. The major differences in epitope expression could be attributed to the degree of sialylation in the three antigens. The antigens from ovarian tumours expressed I(Ma) blood group determinants (defined by the antibody LICR-LON-M18) which were partially masked by sialic acid. With NCRC-11 defined antigen from breast carcinoma, this determinant was totally masked by sialic acid although neuraminidase treatment clearly exposed epitopes reactive with M18 antibodies.

High-Mr glycoprotein profiles in human milk serum and fat-globule membrane

Gradient-polyacrylamide-gel electrophoresis of human milk serum separated three high-Mr glycoprotein bands. The properties of the components corresponding to the three bands (tentatively termed 'Components C, B and A' in their order of migration) were compared by staining with four monoclonal antibodies and lectins. Components B and C both reacted with the four antibodies, but Component A did not. Components B and C were stained with peanut (Arachis hypogaea) agglutinin (PNA) and wheat (Triticum)-germ agglutinin (WGA), Component A being stained with soya-bean (Glycine max) agglutinin as well as PNA and WGA. These results suggest that Components B and C were related molecules, whereas Component A was markedly different from them. The reactivities of Components B and C were the same as those of PAS-0, a high-Mr periodate/Schiff (PAS)-positive glycoprotein previously isolated from human milk fat-globule membrane (MFGM). Component C, whose electrophoretic mobility was the same as PAS-0, could have been a soluble form of PAS-0. A high-Mr glycoprotein having the same properties as Component A was also observed in MFGM. The amino acid composition of the isolated Component A was significantly different from that of Component C and PAS-0, high threonine and serine contents being characteristic of Component A. The carbohydrate content of Component A was 65-80%, and was much higher than that of Component C and PAS-0. Fucose, galactose, N-acetylglucosamine, N-acetylgalactosamine and sialic acid were each detected as constituent sugars of Component A. Component A represents, therefore, a new high-Mr glycoprotein species in human milk serum and MFGM. Since these glycoproteins were high-Mr mucin-like glycoproteins, the names 'HM glycoprotein-A' and 'HM glycoprotein-C' were proposed for Component A and Component C (PAS-O) respectively.

Multiple epitopes on a human breast-carcinoma-associated antigen

The monoclonal antibody (MAb) NCRC-11 identifies an epitope expressed variably in human breast cancer. The degree of expression of this epitope in primary operable tumours is closely related to the subsequent clinical course of the disease (Ellis et al., 1985). The target antigen for NCRC-11 was isolated from subcellular membranes of breast carcinomas and purified by immunoadsorbent chromatography. NCRC-11 epitopes were expressed upon a large glycoprotein of more than 400 kd. This material was susceptible to degradation by pronase and papain and contained N-acetylglucosamine, as indicated by its binding to wheat-germ agglutinin. The NCRC-11-defined antigen expressed epitopes for the anti-human milk-fat globule membrane antibodies HMFG-1 and HMFG-2, and other antibodies against epithelial membrane antigens (EMA, LICR-LON-M8). The reactivity of these antibodies with tumour membranes was also similar, but not identical, to that of the NCRC-11 antibody. In competitive binding-inhibition assays, these antibodies partially inhibited the binding of 125I-NCRC-11 antibody to antigen, suggesting that the epitopes involved are topographically closely associated. Sandwich immunoassays demonstrated that NCRC-11 epitopes are likely to represent repeated structures of the NCRC-11 antigen. The findings presented are interpreted as indicating that the NCRC-11 antigen expresses a variety of epitopes which are associated with normal differentiation and malignant change.