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Biomedical subjects

R A Reisfeld

Publications and source records attributed to R A Reisfeld.

At least 163 records · Page 9Linked to original sources
PubMed1984

Detection of ganglioside GD2 in tumor tissues and sera of neuroblastoma patients.

A murine monoclonal antibody (monoclonal antibody 126) produced against cultured human neuroblastoma cells (LAN-1) was found to be specifically directed to a disialoganglioside (GD2) antigen preferentially expressed on both cell lines and tissues derived from melanoma and neuroblastoma. In enzyme-linked immunosorbent assays, monoclonal antibody 126 failed to react with leukemic and lymphoblastoid cells as well as with a variety of carcinoma and sarcoma cell lines. Immunohistological analysis by the immunoperoxidase technique revealed strong reactivity of monoclonal antibody 126 with frozen and formaldehyde-fixed neuroblastoma and melanoma tissues. Tissues from patients with glioma or with small cell cancer of the lung showed faint staining, whereas those from individuals with sarcoma, lymphoma, and a variety of other neoplasms proved to be negative. Sera of neuroblastoma patients showed significantly elevated GD2 levels compared to normal children (p less than 0.001) and children with other tumors (p less than 0.001) as determined by a quantitative competitive enzyme-linked immunosorbent assay. Furthermore, the GD2 serum level of one neuroblastoma patient, when followed serially, was found to correlate with progression of disease, suggesting the potential usefulness of this assay for the diagnosis and monitoring of neuroblastoma.

Antibodies, Monoclonal↗
PubMed1983

N-terminal amino acid sequences of the alpha and beta chains of HLA-DR1 and HLA-DR2 antigens.

The N-terminal amino acid sequences of the alpha and beta chains of HLA-DR1 and HLA-DR2 antigens were obtained with subnanomole quantities of material by using a gas-liquid solid-phase sequencer. A comparison of the N-terminal amino acid sequences of HLA-DR1 and HLA-DR2 alpha chains revealed no differences. However, in the first 35 N-terminal residues of the beta chains from HLA-DR1 and HLA-DR2 antigens, two regions of variability are readily apparent, each comprising about six amino acids. Conceivably one or both of these variability regions may be responsible for the serologically defined polymorphism of HLA-DR alloantigens.

Amino Acid Sequence↗
PubMed1983

Biosynthesis and secretion of fibronectin in human melanoma cells.

The biosynthesis and secretion of cellular fibronectin from human melanoma cells have been investigated by pulse-chase/immunoprecipitation analysis. Melanoma cells synthesize endoglycosidase H (Endo H)-sensitive glycoprotein precursors of fibronectin glycoproteins which chase to an Endo H-resistant monomer with an apparent Mr of 240,000 (240 K). This molecule, which has a significantly higher molecular weight than normal plasma or cellular fibronectin, is rapidly secreted by melanoma cells, resulting in the secretion of 80% of newly synthesized fibronectin in 120 min, following a 10-min biosynthetic pulse. This active secretory process can be inhibited by brief exposure of melanoma cells to sodium monensin (10(-7) M), which also results in a modified fibronectin of lower apparent Mr. Monosaccharide-incorporation studies of melanoma fibronectin reveal that monensin significantly inhibits galactose and fucose incorporation into this glycoprotein, correlating with reported effects of monensin on Golgi apparatus functions. These studies indicate that this tumor-associated and biosynthetically altered cellular fibronectin is a rapidly secreted major N-linked glycoprotein of metastatic human melanoma cells.

Cells, Cultured↗
PubMed1983

Anti-HLA antibodies of predetermined specificity: a chemically synthesized peptide induces antibodies specific for HLA-A,B heavy chain.

A chemically synthesized dodecapeptide (Asp-Ala-Ala-Ser-Pro-Arg-Glu-Glu-Pro-Arg-Ala-Pro), consisting of residues 39 through 50 of the HLA-B7 heavy chain sequence and containing a highly hydrophilic hexapeptide segment (Pro-Arg-Glu-Glu-Pro-Arg), induced antibodies that bound specifically to free HLA-A, and HLA-B heavy chains and to the soluble dodecapeptide. Although these antibodies reacted with free HLA-A,B heavy chains in blots on nitrocellulose, they failed to immunoprecipitate the HLA-A,B-beta 2-microglobulin antigen complex solubilized from human lymphoblastoid cells by nonionic detergents. These observations suggest that the physical characteristics of this particular soluble hydrophilic dodecapeptide may closely resemble nonallotypic determinants expressed by free HLA-A,B heavy chains and that such antigenic sites may be modified by conformational changes in the native HLA-A,B heavy chain-beta 2-microglobulin complex.

Amino Acid Sequence↗
PubMed1983

Generation of protein-reactive antibodies by short peptides is an event of high frequency: implications for the structural basis of immune recognition.

Recent studies have shown that chemically synthesized small peptides can induce antibodies that often react with intact proteins regardless of their position in the folded molecule. These findings are difficult to explain in view of the experimental and theoretical data which suggest that in the absence of forces provided by the folded protein, small peptides in aqueous solution do not readily adopt stable structures. In order to rationalize the two findings, there has been general acceptance of a stochastic model which suggests that the multiple conformers of a peptide in solution induce sets of antibodies with a small percentage reactive with conformations shared by the folded protein. This stochastic model has become less tenable as the success rate for the generation of protein-reactive anti-peptide antibodies has grown. To test the stochastic model, we have used monoclonal anti-peptide antibodies as a way of estimating the frequency with which small peptides induce antibodies that react with folded proteins. We have made monoclonal antibodies to six chemically synthesized peptides from three proteins. The frequency with which the peptides induce protein-reactive antibodies is at least 4 orders of magnitude greater than expected from previous experimental work and vastly different from what would be predicted by calculating the possible number of peptide conformers in solution. These findings make the stochastic model less likely and lead to consideration of other models. Aside from their practical significance for generation of highly specific reagents, these findings may have important implications for the protein folding problem.

Amino Acid Sequence↗
PubMed1983

Monoclonal antibody-directed effector cells selectively lyse human melanoma cells in vitro and in vivo.

Monoclonal antibody 9.2.27 (mAb 9.2.27) directed to a chondroitin sulfate proteoglycan on human melanoma cells was able to suppress tumor growth in athymic (nu/nu) mice more effectively when bound with polyethylene glycol to murine effector cells than when injected alone. These "armed" effector cells also proved more effective than the monoclonal antibody in eliciting antibody-dependent cellular cytotoxicity against human melanoma target cells in vitro.

Animals↗
PubMed1983

Monoclonal antibody and an antibody-toxin conjugate to a cell surface proteoglycan of melanoma cells suppress in vivo tumor growth.

A monoclonal antibody directed against a cell surface chondroitin sulfate proteoglycan of human melanoma cells, 9.2.27, and its diphtheria toxin A chain (DTA) conjugate were investigated for their effects on in vitro protein synthesis and in vivo tumor growth of human melanoma cells. The 9.2.27 IgG and its DTA conjugate display similar serological activities against melanoma target cells but only the conjugate can induce consistent in vitro inhibition of protein synthesis and toxicity in M21 melanoma cells. However, both 9.2.27 IgG and its DTA conjugate effect significant suppression of M21 tumor growth in vivo in an immunotherapy model of a rapidly growing tumor in athymic nu/nu mice, suggesting that other host mechanisms may mediate monoclonal antibody-induced tumor suppression.

Animals↗
PubMed1983

Inhibition of anchorage-independent growth of human melanoma cells by a monoclonal antibody to a chondroitin sulfate proteoglycan.

Anchorage-independent growth of tumor cells constitutes a phenotype highly associated with malignant transformation and appears to be important in the ultimate event of tumor metastasis, i.e., secondary tumor colonization. The role of a specific, melanoma-associated chondroitin sulfate proteoglycan population in anchorage-independent growth was assessed. Melanoma cells cultured in soft agar containing monoclonal antibody (mAb) 9.2.27, which recognizes such molecules on the surface of these cells, showed a 67-74% specific decrease in their colony formation. In contrast, neither mouse myeloma IgG nor monoclonal anti-HLA-A,B,C antibody (W6/32) had any effect on colony formation of the melanoma cells grown in soft agar. Human melanoma cells cultured in the presence of mAb 9.2.27 or W6/32 did not exhibit any changes in their DNA or protein synthetic metabolism. These findings suggest that 9.2.27-defined chondroitin sulfate proteoglycans on the surface of human melanoma cells may be involved in cell--cell interaction important in anchorage-independent growth.

Antibodies, Monoclonal↗
PubMed1982

A recurrent idiotype on monoclonal anti-human Ia antibodies.

We report a recurrent idiotype on a remarkably high fraction (4/19) of murine monoclonal antibodies specific for human Ia monomorphic determinants and elicited by separate immunizations. For three of them, the shared idiotype is associated with the antigen-combining site. These results indicate that the spectrum of mouse antibody responses to human Ia antigens may be based on recurrent idiotypes, suggesting a limited potential repertoire of murine monoclonal antibodies to human Ia antigens. Anti-idiotypic reagents might be helpful in dissecting this repertoire and to generate a mirror image of a human Ia antigenic map. Furthermore, antisera to the idiotype of antibodies specific for human Ia monomorphic determinants might help in elucidating the interactions between Ia molecules and receptors on immune cells.

Animals↗
PubMed1982

A high yield purification procedure for alpha and beta chains of HLA-DR antigens.

A procedure is described for purifying to homogeneity the alpha and beta chains of HLA-DR antigen from the homozygous human lymphoid cell line LG-2. The procedure involves a combination of lectin affinity as well as classical and high pressure liquid chromatography. From 100 g of packed cells, 8 mg (235 nmol) of alpha chain and 7 mg (205 nmol) of beta chain were isolated.

Amino Acid Sequence↗
PubMed1982

Association of human and bovine beta 2-microglobulins with detergent solubilized HLA-A,B antigens.

The association of human and bovine beta 2-microglobulins with detergent solubilized HLA-A,B antigens was analyzed by a direct binding assay using radiolabeled beta 2-microglobulin and an immunoadsorbent containing a monoclonal antibody to the HLA-A,B heavy chains. Binding of beta 2-microglobulin to HLA-A,B heavy chains could be saturated with respect to the amount of membrane glucoprotein in the system and reached steady state after 6 h at 37 degrees C. Inhibition of [125I]beta 2-microglobulin binding to HLA-A,B heavy chains by beta 2-microglobulin purified from human urine or bovine colostrum resulted in identical inhibition curves and apparent dissociation constants of 1 X 10(-8) M. This evidence suggests that beta 2-microglobulins from different species have similar binding sites for HLA-A,B heavy chains.

Animals↗
PubMed1982

Unique glycoprotein-proteoglycan complex defined by monoclonal antibody on human melanoma cells.

A monoclonal antibody, 9.2.27, with a high specificity for human melanoma cell surfaces has been utilized for biosynthetic studies in M21 human melanoma cells to define a unique antigenic complex consisting of a 250-kilodalton N-linked glycoprotein and a high molecular weight proteoglycan component larger than 400 kilodaltons. The 250-kilodalton glycoprotein has endoglycosidase H-sensitive precursors and shows a lower apparent molecular weight after treatment with neuraminidase. The biosynthesis of the proteoglycan component is inhibited by exposure of M21 cells to the monovalent ionophore monensin, this component can be labeled biosynthetically with 35SO4, is sensitive to beta-elimination in dilute base, and is degraded by both chondroitinase AC and ABC lyases, suggesting that it is a chondroitin sulfate proteoglycan. These data demonstrate that the antigenic determinant recognized by monoclonal antibody 9.2.27 is located on a glycoprotein-proteoglycan complex which may have unique implications for the interaction of glycoconjugates at the human melanoma tumor cell surface.

Antibodies, Monoclonal↗
PubMed1982

Immunochemical and biosynthetic analysis of monoclonal antibody-defined melanoma-associated antigen.

Immunoprecipitation studies with application of monoclonal antibody F11 originally made to a partially purified spent medium antigen of melanoma cells, made it possible to delineate the molecular profiles of both the cell associated and spent medium antigens recognized on melanoma cells intrinsically labeled with glycoprotein precursors. F11 distinguishes a glycoprotein of Mr 100,000 (100 K) in the spent media of melanoma cells while a parallel analysis of detergent lysates of cells reveals a pattern of three glycoproteins of Mr 75, 77, and 100 K. Pulse-chase analysis of the biosynthesis of these antigens indicated that F11 first recognizes the 75 and 77 K antigens in the absence of a 100K component suggesting strongly that these molecules contain an antigenic site recognized by F11. The 100 K antigen appears later in the pulse-chase analysis with kinetics that suggest some of the 75 and 77 K antigens are biosynthetic precursors of the 100 K antigen. This molecule is ultimately secreted into the extracellular media and appears to be a sialoglycoprotein judging from its sensitivity to neuraminidase. A cross-reactive species with an approximate Mr 90 K is also recognized by F11 in indirect immunoprecipitation analysis of spent media from a neuroblastoma cell line indicating that a common antigenic site exists on this secreted but structurally different neuroblastoma antigen. Thus, a combination of immunochemical and biosynthetic analyses of cell-associated and secreted antigens recognized by monoclonal antibody F11 demonstrate such molecules can differ structurally when isolated from the same or different tumor cells. These findings indicate the necessity to establish molecular profiles of melanoma-associated glycoprotein antigens recognized by monoclonal antibodies to characterize and define their potential biological functions within tumor cells.

Antibodies, Monoclonal↗
PubMed1982

Serological and biochemical analyses of monoclonal antibodies to human melanoma-associated antigens.

Monoclonal antibodies submitted and exchanged by participating laboratories were analyzed serologically and biochemically in accordance with the goals and aims of the Workshop on Monoclonal Antibodies to Melanoma. Serological evaluation of the workshop panel revealed that when a variety of tumor and normal cell lines were tested by enzyme-linked immunoassay, a majority of antibodies reacted preferentially with melanoma cells. Indirect immunoprecipitation analysis of those antibodies that bound staphylococcal protein A provided molecular weight estimates for some antigens and additional information that suggested possible commonalities among antigens recognized by antibodies 9.2.27, 225.28S and 763.24TS. Competitive binding analyses demonstrated that antibodies 225.288 and 763.24TS bound separate and distinct epitopes from that recognized by antibody 9.2.27 on the core glycoprotein of melanoma-associated chondroitin sulfate proteoglycans. Immunoperoxidase staining of fresh frozen melanoma tissue with antibody 9.2.27 revealed a limited tissue distribution and preferential association with the cell surface of human melanoma cells.

Antibodies, Monoclonal↗
PubMed1981

Immunochemical delineation of an oncofetal antigen on normal and simian virus 40-transformed human fetal melanocytes.

Human melanoma cells of uveal origin shed 94,000- and 240,000-dalton glycoproteins in common with most melanoma cell lines of dermal origin. Normal human melanocytes derived from fetal uvea shed a 90,000-dalton glycoprotein that was found to be immunologically identical with the 94,000-dalton glycoprotein of melanoma cells. Expression of this 90,000-dalton molecule was confined to fetal cells of ectodermal origin. After simian virus 40 (SV40) transformation of human fetal melanocytes, there was an apparent increase in molecular size of this component to 94,000 daltons. In contrast, the 240,000-dalton glycoprotein was not synthesized or shed by uninfected or SV40-transformed fetal melanocytes. These data suggest that the 94,000-dalton glycoprotein is an oncofetal antigen of ectodermal origin.

Antigens, Neoplasm↗