Biomedical subjects

M J Mattes

Publications and source records attributed to M J Mattes.

At least 55 records · Page 3Linked to original sources

PubMed1993

Biochemical and immunological characterization of the human carcinoma-associated antigen MH 99/KS 1/4.

We have characterized the 38-kDa transformation-associated membrane glycoprotein MH 99, whose expression is highly elevated in many epithelial malignancies. A spontaneous cleavage of MH 99 into a 32- and a 6-kDa chain in some carcinoma cell lines was recently shown. Sequence homologies to nidogen, a matrix-adhesion molecule, support the suggestion of a receptor-like function. In this study, we characterized biochemical and immunogenic aspects of MH 99. Transformed epithelial cell lines which do not spontaneously cleave MH 99 were exposed to 8 proteases with distinct specificities. Each of the enzymes produced similar specific fragmentation into chains of about 30 to 32 and 6 kDa, indicating a characteristic cleavage site of MH 99. The fragments were not distinguishable from those in carcinoma cells showing spontaneous cleavage of MH 99. The specific fragmentation depends on the localization in intact membranes and is not shared by other membrane proteins. N-glycosylation of MH 99 of about 4 kDa was exclusively found on the 32-kDa fragment. Characterization of antigenic epitopes was performed using 16 different monoclonal antibodies (MAbs). Only 2 independent determinants were found. One is located on the 32-kDa chain and is recognized only by the MM 104 MAb. The other 15 antibodies bind to a dominant epitope on the 6-kDa fragment which can be divided into 3 overlapping sub-epitopes. The unique features of MH 99 indicate that its immunogenic epitopes are mainly located at its 6-kDa chain, and support the suggestion of a transformation-associated cell-surface receptor which might be proteolytically regulated.

Animals↗

PubMed1993

Re-evaluation of the concept of functional affinity as applied to bivalent antibody binding to cell surface antigens.

Although it is recognized that the bivalent binding of an antibody to a multivalent antigen cannot be characterized by true affinity, "functional affinity" is frequently determined. "Functional affinity" is calculated by the same methods used for true affinity, and is presumed to have similar biological significance. The data presented herein demonstrate, for IgG antibodies binding to cell surface antigens, that "functional affinity" does not adequately describe the interactions that occur. First, the dissociation rate was not first-order, but rather reflected heterogeneity of bound Ab. A minority of bound Ab (probably monovalently bound) dissociated relatively rapidly, while the majority dissociated very slowly, and, for most purposes, should be considered irreversibly bound. Although irreversible binding is incompatible with a state of equilibrium, the dissociation rate was greatly increased in the presence of free Ab, which may explain why equilibrium is reached in a Scatchard-type experiment. In addition, "functional affinity" was found to vary depending on trivial experimental conditions, such as the volume of incubation. Thus, antibodies do not possess a single "functional affinity", but rather a spectrum of "functional affinities", which are therefore of little value in comparing different antibodies and cannot be used to predict the extent of binding under other experimental conditions. Both of these discrepancies can be attributed to the effect of bivalent Ab binding. We conclude that "functional affinity" determination is inappropriate.

Animals↗

PubMed1993

The specificity of alternative complement pathway-mediated lysis of erythrocytes: a survey of complement and target cells from 25 species.

Sera from 20 species of mammals were tested for their ability to lyse erythrocytes from 18 species of mammals and birds by the alternative complement pathway. Erythrocytes were not lysed by homologous complement, with one minor exception, but all erythrocytes tested were lysed by at least one complement source, and all sera tested except that of the horse lysed at least one type of erythrocyte. Control experiments indicated that lysis was via the alternative complement pathway and that antibodies were not involved. Complement from the various species could be ranked from most active to least active, and erythrocytes could be ranked from most susceptible to least susceptible. There was an inverse correlation between complement activity and erythrocyte susceptibility. The ranking of the orders of placental mammals, from strongest to weakest complement, was carnivore > artiodactyl (ruminants and swine) > primate = armadillo > rodent > rabbit > horse. Opossum serum had activity that placed it in the centre of this range. Ferret complement, the most potent tested, lysed all erythrocytes tested except for homologous erythrocytes, with APCH50 titres as high as 4000. Although the overall reactivity pattern was clear, there were several striking exceptions. For example, the only complement source which lysed ferret erythrocytes was sera of the mouse. The amount of sialic acid present on erythrocytes of 14 mammals was determined, and was, in general, directly correlated with resistance to alternative complement pathway lysis, although there were prominent exceptions to this correlation, involving erythrocytes of the horse, burro and human. All 20 types of complement were also tested for their ability to lyse antibody-coated human tumour cells, under conditions in which both the classical and alternative complement pathways were functional. The data obtained suggest that alternative pathway activation is, in some cases, a major factor determining the effectiveness of a particular complement source in the lysis of xenogeneic tumour cells.

Animals↗

PubMed1992

Analysis of high complement levels in Mus hortulanus and BUB mice.

BUB/BnJ mice were previously identified as having exceptionally potent complement activity, relative to common mouse strains, in the lysis of antibody-coated human tumor cells. We describe herein our investigation into the molecular and genetic basis for this difference between mouse strains, and also our results with wild mice and mouse strains recently derived from the wild, to determine whether low complement levels are characteristic of wild mice. BUB complement was compared with complement from BALB/c and C57BL/6 mice. BUB mice had higher levels of most individual classical pathway components, except for C1, than the other two strains, but the difference was generally only 2-3-fold, so insufficient to fully explain the difference observed with tumor target cells. CH50 titers on antibody-coated sheep erythrocytes also demonstrated only a 2-4-fold difference. However, CH50 titers on antibody-coated human erythrocyte target cells demonstrated a difference similar in magnitude to that seen with human tumor targets. These results suggest that the difference between mouse strains depends partly on the use of human, rather than sheep, target cells. In an assay for alternative complement pathway activity using neuraminidase-treated human erythrocytes as targets, complements of BALB/c and BUB mice were similar in activity, suggesting that the difference between mouse strains is manifested in the early steps of complement activation. Analysis of F1 and backcross mice suggested that the difference in complement level between BUB and BALB/c or C57BL/6 mice is controlled by semi-dominant genes, and cannot be attributed to a single gene. Wild mice and mice recently derived from the wild generally had low complement levels, similar to most laboratory mice. However, three strains of aboriginal mice, including Mus hortulanus (spicilegus) and Mus spretus, had complement levels higher than that of BUB mice, and as high as sera from the rabbit or rat, which are the most potent known complement sources for the lysis of human tumor cells. In comparison with BUB mouse sera, M. hortulanus sera had at least four-fold higher levels of C3, C6, C8 and C9, and some or all of these differences may explain its higher total complement activity. In the lysis of antibody-coated human erythrocytes, M. hortulanus serum was more potent than any other complement source tested, including sera of the guinea pig, rat, rabbit or human. These strains may be useful in investigating the role of complement in various pathological processes, and in investigating the genetic regulation of the complement system.

Animals↗

PubMed1992

The fate of antibodies bound to the surface of tumor cells in vitro.

The fate of monoclonal antibodies binding to the surface of human tumor cells in vitro was investigated. Seven antibodies, labeled with 125I, were tested on four cell lines, which included a melanoma and carcinomas of the ovary, kidney, and lung. The antibodies were selected only by the criterion that they not be rapidly internalized via coated pits, so that they would be representative of most antibodies reacting with cell surface antigens. After allowing binding during a 2-h incubation, unbound antibody was removed, and the release of intact or degraded antibody in the supernatant was monitored. The data demonstrate that most bound antibody was gradually degraded and released from the cell over a 2-3-day period, probably via internalization, while only a small fraction, less than 20% for most antibodies, appeared to dissociate intact. One exceptional antibody, MW207, dissociated largely intact. The release of intact antibody was virtually complete within 4 h, and radioactivity released after this time was predominantly in degraded form. These results demonstrate that antibody binding to the surface of viable cells must in general be considered irreversible, and hence the concept of affinity is not applicable. Since an Fab fragment of one of the antibodies dissociated rapidly, such irreversible binding appears to require bivalent attachment. Another conclusion of this study is that most antibodies binding to the cell surface are gradually internalized, which we suggest is due to the normal turnover of cell surface constituents via non-clathrin-dependent endocytosis. Several experimental approaches indicated that a large fraction of antibody retained by the cells, for at least 2 days after binding, was present at the cell surface.

Ammonium Chloride↗

PubMed1991

Rapid blood clearance of immunoglobulin G2a and immunoglobulin G2b in nude mice.

An extremely rapid blood clearance rate of murine IgG2a antibodies was found in all strains tested of outbred Swiss nu/nu mice, including mice from the major commercial suppliers. The clearance half-life was less than 5 h, in comparison to a 4-5-day half-life in BALB/c mice. Therefore, most of the IgG2a antibody injected i.v. in such mice is cleared before it can reach interstitial fluid, which interferes with immunotherapy and immunodetection experiments. Individual nude mice varied greatly in their IgG2a clearance rates, which hampered investigation of the phenomena. In our experience, approximately three-fourths of nude mice had a rapid or intermediate clearance rate, whereas the remainder had an approximately normal clearance rate. The clearance rate in nude mice was age-dependent, at least in some instances, in that a rapid clearance rate was observed at 2 months of age, whereas the same mice retested at 4 months of age had a normal clearance rate. Rapid clearance could be inhibited by increasing the dose injected: 100 micrograms/mouse resulted in a normal clearance rate, whereas 30 micrograms/mouse was insufficient to inhibit rapid clearance. The clearance rate of IgG2b antibodies was affected similarly to that of IgG2a, whereas the clearance rate of IgG1 and IgG3 was not affected. The Fc region of IgG2a was required in order for rapid clearance to occur. Biodistribution experiments demonstrated that rapid blood clearance was due, at least partially, to binding to the liver and spleen. To determine the genetic basis for rapid IgG2a clearance, approximately 20 inbred and outbred mouse strains were tested. Unexpectedly, nu/+ as well as nu/nu outbred Swiss mice displayed rapid clearance, whereas control +/+ mice did not, so this phenotype appears to be a dominant effect of the nu mutation. BALB/c nu/nu and nu/+ mice did not display rapid clearance, which may be due to expression of the Igh-1a gene, which codes for the IgG2a present in BALB/c mice and in the monoclonal antibodies used in these studies. In conclusion, this clearance effect must be considered in experiments involving murine IgG2a or IgG2b antibodies in outbred Swiss nude mice, except those in which high antibody doses of greater than 0.1 mg/mouse are used. One method of circumventing this problem is to increase the antibody dose injected; a better but more long-range method is to develop strains of outbred nude mice that do have this characteristic.

Animals↗

PubMed1991

Galactose-conjugated antibodies in cancer therapy: properties and principles of action.

Galactose conjugation of antibodies causes them to be recognized by the hepatic asialoglycoprotein receptor and therefore cleared very rapidly from the blood. In these investigations, some effector functions of galactose-conjugated antibodies were assayed, and several applications to experimental tumors in vivo were demonstrated. Galactose conjugation did not interfere with two antibody functions in addition to antigen binding, namely complement-mediated cytotoxicity and antibody-dependent cell-mediated cytotoxicity. This conjugation procedure was originally developed for its potential use in localized immunotherapy, such as i.p. Injection of galactose-antibody conjugates i.p. demonstrated, more conclusively than other methods that have been used, that the presence of ascites causes prolonged retention of antibody in the peritoneal cavity and that this effect is correlated with the volume of ascites present. In mice bearing i.p. tumor xenografts, i.p. injection of galactose-antibody conjugates resulted in high tumor/nontumor ratios at 28 h after antibody injection, with values of 40:1, 43:1, 77:1, and 11:1 for the blood, kidney, lung, and spleen, respectively, although the ratio was only 4:1 for the liver. Control experiments demonstrated that i.p. injection of unconjugated antibody or a galactose-conjugated nonreactive antibody produced much lower tumor/nontumor ratios. In investigations of possible systemic application of galactose-antibody conjugates, we found that injection of large amounts of an inhibitor that binds competitively to the hepatic receptor, asialo-bovine submaxillary mucin, can block clearance of galactose-conjugated antibodies for 2-3 days. In this way, high blood levels of antibody can be maintained for 2-3 days, thus allowing penetration and binding to solid tumors, followed by very rapid blood clearance. With this approach, using a human carcinoma growing s.c. in nude mice, high tumor/nontumor ratios were obtained 4 days after injection, with mean values of 43:1, 18:1, 17:1, and 15:1 for the blood, kidney, lung, and spleen, respectively, although the ratio for the liver was only 1.7:1. The blood level at this time was 0.04 +/- 0.02% (SD) of the injected dose/g, while the tumor level was 1.69 +/- 1.29% of the injected dose/g. In conclusion, galactose-conjugated antibodies appear to have diverse applications in regional or systemic immunotherapy.

Animals↗

PubMed1991

Normal tissue reactivity of four anti-tumor monoclonal antibodies of clinical interest.

Normal tissue reactivity on frozen sections was examined with 4 monoclonal antibodies (MAbs) that were reported previously to be negative or weakly reactive with normal tissues, and strongly reactive with some types of carcinoma. All 4 antibodies reacted strongly with certain normal epithelial cells. The antibodies tested include 2 antibodies to ovarian cancer, MOv18 and MOv19, one antibody to breast cancer, H23, and one antibody reactive with a range of carcinomas, B72.3. MOv18, MOv19 and H23 reacted with many normal glandular and ductal epithelial cells, while B72.3 reacted most strongly with secretions of the small intestine epithelium and the suprabasal squamous epithelial cells of the esophagus. Since the tissue distribution of MOv19 was very similar to that of another antibody described previously, MW207, these two antibodies were compared by competitive binding inhibition, and found to recognize the same epitope. Our data emphasize the importance of repeated, independent tests of antibody specificity.

Antibodies, Monoclonal↗

PubMed1990

Patterns of antigen distribution in human carcinomas.

Ten epithelial-specific monoclonal antibodies, including monoclonal antibodies to antigens that have been used extensively in immunodiagnosis and immunotherapy experiments, were tested for reactivity with 20 human carcinomas each of the colon, lung, and breast. The antibodies tested included B72.3, OC125, and antibodies to carcinoembryonic antigen, the 17-1A antigen, and the milk fat globule mucin antigen (epithelial membrane antigen). Striking differences in the pattern of antigen distribution were seen, with each antibody having a fairly consistent staining pattern, which was dependent on the tumor type. Two antibodies reacted with most or all tumor specimens and, when positive, reacted homogeneously with apparently every cell in the specimen. Other antibodies consistently produced a variegated staining pattern, typically with areas of positive cells surrounded by areas of negative tumor cells. A third pattern was strong localization to the luminal edge and/or secretions of glandular tumors; this pattern was seen primarily in colon carcinomas which have more well-developed glandular structures than breast or lung carcinomas. A correlation with biochemical properties of the antigens was evident, in that mucins or mucin-related antigens generally produced variegated staining of lung and breast carcinomas and luminal edge/secretion staining of colon carcinomas. Such differences in antigen distribution are likely to be a major factor in developing methods for immunodiagnosis and immunotherapy.

Antibodies, Monoclonal↗

PubMed1990

Breast tumor radioimmunodetection with a 111In-labeled monoclonal antibody (MA5) against a mucin-like antigen.

Monoclonal antibody MA5 recognizes a determinant displayed on high molecular weight antigens associated with secretory and malignant breast epithelial cells. MA5 reactivity with greater than 95% of primary and metastatic breast tumors, surface expression of the antigen, as well as its ability to localize within breast tumor xenografts prompted this initial study to determine the efficacy of MA5 to localize breast tumors by radioimmunoscanning. A total of 17 patients was monitored, each receiving 2 mg of purified MA5 labeled with 5 mCi of 111In. Some patients also received 3 or 18 mg of unlabeled carrier antibody (MA5); no serious allergic reactions were noted. Primary tumors, bone lesions, soft tissue recurrences, and lung metastases greater than 3 cm in diameter were detectable, whereas only one lesion (hilar node) less than 3 cm was localized. Significant antibody accumulation was noted in the liver and less significant uptake in the spleen and bone. The extensive fibrosis and poor vascularization of breast tumors may partly explain the limited sensitivity obtained thus far. The imaging results obtained with MA5 are compared with other antibodies which we show recognize the same antigens.

Antibodies, Monoclonal↗

PubMed1989

Mouse strains with typical mammalian levels of complement activity.

Common laboratory mouse strains have very low complement levels relative to humans, rats, guinea pigs, rabbits and other mammals, which limits the value of the mouse as an experimental model. We therefore tested serum complement levels of 43 mouse strains and 11 rat strains, for the purpose of selecting a convenient laboratory animal having high complement levels. Total complement activity was determined with both erythrocytes and human tumor cells as targets. Eight mouse strains were identified that have complement levels comparable to those of other mammals. These mouse sera lyse tumor cell targets as well as sera from humans, rats or guinea pigs, although they are somewhat less active than rabbit sera. They are relatively inefficient in lysing erythrocyte targets, yet are as active as rabbit serum in this assay. Target cell lysis was demonstrated to be via the classical pathway of complement activation. Of the eight 'high complement' mouse strains, four were recently derived from wild mice, and one, SF/CamEi, was derived from wild mice in 1951. The three other strains, BUB/BnJ, DA/HuSn and RIIIS/J, were developed more than 40 years ago, but apparently were not tested previously for complement activity. Using the BUB mouse as a representative of the 'high complement' mice, we assayed levels of the nine complement components, in an attempt to identify the cause of high complement activity. No difference in levels of C1, C2, C4, C8 or C9 was detected between BUB and BDF1 mice. C2 activity was very low in both strains. C3, C5, C6 and C7 activities were higher in BUB mice than in BDF1 mice, indicating that variation in these complement components is responsible for the difference in total complement activity. The genes determining the 'high complement' phenotype appeared to be semi-dominant in F1 hybrids. The 'high-complement' mouse strains, and recombinant strains derived from them, will be useful in a wide range of biomedical research.

Animals↗

PubMed1989

Penetration and binding of antibodies in experimental human solid tumors grown in mice.

Monoclonal antibody localization to human carcinoma xenografts in nude mice was investigated by injecting biotinylated antibody. The antibody used in most experiments, MA103, reacts with a widely distributed human antigen present at a high density on the cell surface and has a relatively high effective affinity, 5.8 x 10(9) M-1. Various doses of antibody were injected, and tumors were collected at various times after injection. Frozen sections were stained by the immunoperoxidase method to detect bound antibody, and adjacent sections were stained with the same antibody in vitro to demonstrate total antigen distribution. In complementary experiments, unconjugated MA103 was injected in high doses to determine whether subsequent in vitro staining of frozen sections by biotinylated MA103 would be inhibited. The results demonstrate that: (a) approximately 0.5 mg antibody was sufficient to saturate antigenic sites on viable tumors cells; (b) saturation was achieved on viable tumor cells throughout the tumor 3 days after injection; (c) in necrotic areas, some antigen was accessible to antibody in vivo, but a considerable fraction of the antigen was inaccessible; (d) at 1 day after injection, stained cells were confined to areas near the blood vessels in the stroma; (e) for i.p. tumors, there was no difference between i.p. and i.v. injection of antibody and no indication of solid tumor penetration directly from the peritoneal cavity; and (f) nonspecific localization of a nonreactive biotinylated monoclonal antibody was weakly detectable and when present was seen as diffuse staining in the connective tissue only. A more limited range of experiments was performed with a second biotinylated antibody, MH99, which reacts with an epithelial cell surface antigen also recognized by many other antibodies, including 17-1A, AUA1, and KS1/4. Results were generally similar, except that a higher dose, 1.5 mg, was required to obtain homogeneous dark staining of tumor cells, and there appeared to be a considerable amount of antigen in viable areas of the tumor that was not accessible in vivo, possibly because it was intracellular. This approach appears to demonstrate tumor localization of antibody more impressively than other methods that have been used. This is partly because of the excellent resolution attained, since the reactive antibody produces a sharp membrane-staining pattern that is totally absent using a nonreactive control antibody. In addition, use of a target antigen that is predominantly on the cell surface, as opposed to cytoplasmic or secreted, is probably important. These data will be of value in attempting to use antibodies for immunotherapy.

Animals↗

PubMed1989

Binding parameters of monoclonal antibodies reacting with ovarian carcinoma ascites cells.

Binding parameters were determined for four mouse monoclonal antibodies reacting with three antigens on the surface of fresh human ovarian carcinoma ascites cells, under nearly physiological conditions. The object of these experiments was to aid in the selection of the optimal monoclonal antibodies for intraperitoneal immunotherapy. The number of antigenic sites per cell, the effective equilibrium association constant (affinity) and the half-life for dissociation were: for Ab MH99, 1.2 x 10(6) sites/cell, (1.9-4.1) x 10(8) M-1, and 4 h; for Ab MX35, (3.2-4.1) x 10(5) sites/cell, (3.4-4.8) x 10(8) M-1, and greater than 10 h; and for Ab MW207, 1.3 x 10(5) sites/cell, (3.6-4.1) x 10(9) M-1, and 3.1 h, respectively. One of the antigens, MH99, is recognized by five different monoclonal antibodies, and competitive inhibition experiments demonstrated that two distinct determinants are present; this antigen is also recognized by the previously described Ab 17-1A. These binding data will aid the rational design of immunotherapy strategies.

Animals↗

PubMed1988

Class 1 (unique) tumor antigens of human melanoma: identification of unique and common epitopes on a 90-kDa glycoprotein.

Antibodies present in the serum of melanoma patient FD detect an antigenic determinant (FD) restricted to the autologous melanoma cell line SK-MEL-131. This cell-surface determinant is carried on a glycoprotein of 90 kDa, designated gp90. Mice were immunized with a partially purified preparation of gp90 derived from SK-MEL-131 clone 1.5, and three murine hybridomas (KF23, KF26, and KF104) secreting monoclonal antibodies (mAbs) detecting this antigen have been generated. Sequential immunoprecipitation experiments demonstrate that the three mAbs and human FD serum react with the same gp90 species. The mAbs, in contrast to FD serum, react with a broad range of cultured cells in assays for cell-surface antigens and immunoprecipitate a gp90 component from radiolabeled extracts of these cells, including autologous FD B cells. We conclude that gp90 from SK-MEL-131 has two types of determinants: restricted (detected by FD serum) and common (detected by the mouse mAbs). gp90 molecules from cell lines other than SK-MEL-131 carry only the common determinant(s). Immunoperoxidase analysis of frozen tissue sections with mAb KF23 demonstrated a restricted gp90 expression in normal tissues (capillary endothelial cells, duct epithelium in sweat glands, breast, and pancreas). Melanomas and sarcomas showed strong gp90 expression, suggesting up-regulation of gp90 synthesis in certain human cancers.

Animals↗

PubMed1988

Monoclonal antibody B72.3 reacts with a core region structure of O-linked carbohydrates.

Monoclonal antibody (moAb) B72.3 appears to be exceptional among the many mouse moAbs reactive with human tumor cells in its degree of tumor specificity. The antigen recognized was characterized as a mucin-like molecule. We report here that B72.3 reacts strongly with ovine submaxillary mucin and that reactivity is abolished by desialylation, suggesting that the determinant recognized is the disaccharide N-acetylneuraminic acid alpha (2----6)-N-acetylgalactosamine, linked to serine or threonine, which might be designated sialylated Tn. A variety of human mucin preparations, including human salivary mucins, and other glycoproteins containing O-linked or N-linked carbohydrates were nonreactive. The data suggest that the determinant recognized is a core structure which is normally not exposed due to chain elongation at C-3 of the N-acetylgalactosamine, which appears to be less frequent in carcinoma cells than in normal cells.

Animals↗

PubMed1987

Class 1 (unique) tumor antigens of human melanoma: partial purification and characterization of the FD antigen and analysis of a mouse polyclonal antiserum.

Serum antibodies from melanoma patient FD were previously shown to detect a unique antigenic specificity (FD) expressed only on the autologous tumor cells (SK-MEL-131) in culture. The FD determinant is carried by a Mr 90,000 glycoprotein (gp90) that binds to concanavalin A but not to lentil lectin or wheat germ agglutinin. After treatment with endo-N-acetylglucosaminidase H, the antigen no longer bound to concanavalin A. These and other properties indicate the gp90 carries mainly high mannose or hybrid N-linked carbohydrate chains. gp90 was partially purified from a detergent-solubilized membrane preparation by chromatography on DEAE-Sepharose, hydroxylapatite, chelating Sepharose, and lectin-agarose columns. Two-dimensional electrophoresis of the final preparation revealed three major components, one of which was identified as the FD antigen since it was specifically removed by precipitation with serum from patient FD. Immunization with the partially purified antigen preparation elicited anti-gp90 antibodies in two of four mice as demonstrated by sequential radioimmunoprecipitation experiments. Absorption experiments demonstrated that the mouse antibodies could, unlike human FD serum, be absorbed by a number of different cell types. Based on these results it is proposed that gp90 in SK-MEL-131 cells has two distinct epitopes, one, unique, detected by autologous FD serum, and another, common epitope or epitopes, detected by the polyclonal mouse sera. The common epitope(s) is present on gp90 in a variety of cells, including allogeneic melanomas and FD-B cells. These findings, which are compared with those on mouse tumor rejection antigens, have clear implications for the understanding of the nature of tumor antigens.

Animals↗

PubMed1987

Mouse monoclonal antibodies to human epithelial differentiation antigens expressed on the surface of ovarian carcinoma ascites cells.

Four different human epithelial differentiation antigens (MT179, MW162, MW207, and MX35) have been defined by mouse monoclonal antibodies obtained from mice immunized with either an ovarian carcinoma cell line or fresh ovarian carcinoma cells. In an attempt to identify tissue-specific antigens restricted to ovarian epithelial cells, sections of a benign ovarian cyst were used as the initial target for screening hybridoma supernatants. The distribution of the antigens detected by these monoclonal antibodies was determined on frozen sections of 24 normal tissues and on 103 cultured cell lines of various histological types. In spite of the method used to select these monoclonal antibodies, they all reacted to some degree with normal epithelial cells in tissues other than ovary. All antibodies were unreactive with nonepithelial cells in frozen sections. These antibodies also reacted with frozen sections of most or all fresh ovarian carcinomas and benign ovarian cysts. All antibodies were unreactive with ABH, Lewis blood group-related antigens and appeared to be different in specificity from previously described well-characterized antigens of ovarian carcinoma cells. MW162 was characterized as a high-molecular-weight mucin-like molecule, and the determinant recognized is probably carbohydrate in nature. MW207 was identified as a Mr 37,000 protein. These monoclonal antibodies and 24 other previously derived antibodies that react with epithelial differentiation antigens were tested for reactivity with the surface of fresh ovarian carcinoma ascites cells and for nonreactivity with normal mesothelial cells. This assay was designed to select monoclonal antibodies that might be effective agents for i.p. therapy or radioimmunodetection of human ovarian carcinoma. Five antibodies with the desired specificity were selected; these were the four new antibodies described herein and MH99, which was characterized previously and recognizes a glycoprotein having Mr 38,000 and 29,000 subunits. The degree of heterogeneity of antigen expression on ascites carcinoma cell was dependent on the particular antigen being examined and was related to the biochemical nature of the antigen. In particular, most ABH and Lewis blood group-related antigens showed a striking degree of heterogeneity.

Animals↗

PubMed1987

Biochemical analysis of two cell surface glycoprotein complexes, very common antigen 1 and very common antigen 2. Relationship to very late activation T cell antigens.

Two mouse monoclonal antibodies (mAb), AJ2 and J143, define two related human cell surface protein complexes, very common antigen 1 (VCA-1) and very common antigen 2 (VCA-2). In the present report, these complexes have been defined with respect to: (i) subunit arrangement; (ii) monoclonal antibody binding sites; (iii) carbohydrate content; (iv) homology to other cell surface protein complexes; and (v) possible functional roles. Analysis of the antigens from a human melanoma cell line, MeWo, reveals that VCA-1 is a noncovalently linked heterodimer of 170- and 140 (designated 1401)-kDa polypeptides. mAb AJ2 reacts with an epitope on the 1401-kDa polypeptide. VCA-2 is composed of the same 1401-kDa polypeptide as VCA-1 and another 170-kDa species; this 170-kDa species consists of a second distinct 140-kDa (designated 140(2)) and a 30-kDa polypeptide which are disulfide-bonded. Indirect evidence indicates that mAb J143 reacts with an epitope on this 170-kDa complex. Peptide mapping has shown that the complexes are members of a family of cell surface proteins that include antigens present on activated T cells (designated very late activation antigens). Since VCA-2 is found predominantly on the basal membrane of adherent cells and its expression increases 12-fold when HUT-102 lymphoblastoid cells are grown as an adherent cell culture, we suggest that VCA-2 plays a role in cellular adherence.

Antibodies, Monoclonal↗