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Biomedical subjects

R A Reisfeld

Publications and source records attributed to R A Reisfeld.

At least 19 recordsLinked to original sources
PubMed1979

Antibody-coated protein A-bearing Staphylococcus aureus: a versatile and stable immune reagent.

The human beta2-microglobulin antigen-antibody system was used as a model to illustrate the versatility of a microradioimmunoassay technique using protein A-bearing Staphylococcus aureus Cowan I strain (SACI) bacteria as a non-specific immunoadsorbent in place of a second antibody. Experimental conditions are described for a sensitive microassay which makes it possible to process large numbers of samples more rapidly and with minimum handling. Furthermore, SACI coated with specific antibodies by mixing with unfractionated antisera are a versatile reagent not only for radioimmunoassays but also for use as molecular probes to characterize cell surface antigens. Antibody-coated SACI could be lyophilized and proved extremely stable in storage thus providing a unique advantage for use in binding inhibition assays and as versatile reagent for clinical and investigative immunology.

Animals↗
PubMed1979

A radioimmunometric antibody-binding assay for evaluation of xenoantisera to melanoma-associated antigens.

A radioimmunometric antibody-binding assay was developed with the use of 125I-labeled protein A of Staphylococcus aureus (SpA) for the evaluation of xenoantisera to human melanoma-associated antigens. Antisera were produced in New Zealand male albino rabbits by the injection of cultured human melanoma cells or soluble, partially purified melanoma-associated antigens isolated from these cells. Xenoantisera were rendered operationally specific for melanoma-associated antigens by absorption with human red cells and cultured lymphoblasts. The methodologic parameters and the quantitative relationships among xenoantisera, cultured melanoma target cells, and 125I-labeled SpA and their effect on the measurement of xenoantibody binding were critically evaluated. Data indicated the usefulness of the radioimmunometric assay in monitoring the efficacy of absorption and in characterizing the specificity of xenoantisera to melanoma-associated antigens. The radioimmunometric binding assay when modified and used as a binding inhibition assay was effective in the assessment of the serologic activity of soluble melanoma-associated antigens and thus may be used to monitor the progress of antigen purification.

Animals↗
PubMed1979

Expression of a sheep red blood cell receptor by a murine lymphoma.

Murine 6C3HED lymphoma cells were found to rosette with sheep red blood cells (SRBC). Normal C3H lymphocytes did not exhibit this property. This rosetting capacity of 6C3HED cells was found to be an accurate and reproducible means for discriminating between normal and tumor cells. The SRBC receptor on these lymphoma cells appeared to be serologically distinct from that expressed by normal human T lymphocytes since reciprocal blocking experiments demonstrated that inhibitory antisera were not cross-reactive. The expression of the SRBC receptor by the 6C3HED cells appeared to correlate with the expression of a tumor-associated antigen and was spatially related to an antigen expressed by 6C3HED and normal neonatal but not adult mouse cells.

Animals↗
PubMed1979

Isolation and immunochemical characterization of antibodies from the sera of cancer patients which are reactive against human melanoma cell membranes by affinity chromatography.

Immunoglobulins were isolated by affinity chromatography from sera of two patients with melanoma, one with sarcoma, and one with carcinoma. The affinity columns were prepared by covalently linking the membrane-rich fraction of biopsied melanoma cells to cyanogen bromide-activated agarose beads. The membrane-rich fractions were prepared by two methods: (a) hypotonic cell lysis, and (b) homogenization and differential centrifugation. Melanoma sera were autologous to melanoma membrane preparations. The isolated immunoglobulins showed immunoreactivity against antigens prepared from melanoma, sarcoma, and carcinoma cells by complement fixation but not against antigens prepared from normal human liver and lung tissues. Absorption of the isolated immunoglobulins with rabbit anti-human immunoglobulin immunobeads resulted in complete elimination of the complement-fixing antibody titer in one instance, whereas reduction occurred in other samples. Similar absorption with rabbit anti-human immunoglobulin M immunobeads resulted in reduction, but not complete elimination, of the antibody titers against target tumor cell preparations. These results suggest the presence of immunoreactive immunoglobulin G in all immunoglobulins and immunoglobulin M in some. Absorption of the isolated immunoglobulins with cultured sarcoma cells reduced but did not completely abolish antibody activity against autologous or allogeneic melanoma target antigen, whereas it did completely abolish activity against sarcoma target antigen. However, absorption with cultured allogeneic melanoma cells abolished the antibody activity against melanoma as well as sarcoma target antigens. The antibody titers of the isolated immunoglobulins were not affected by absorption with cultured lymphoblastoid cells. Since cultured melanoma and sarcoma cells were known to contain oncofetal antigen(s), these results suggest that the isolated immunoglobulins from cancer sera by melanoma membrane affinity chromatography were of at least two specificities: (a) antioncofetal; and (b) antitumor associated. The former group may be comprised of antibody to cross-reactive antigens associated with different histological types of tumors. However, it was apparent that a portion of the antibody activity was against common tumor-associated antigen(s). These results provide further evidence for the presence of common antigen(s) associated with biopsy specimens of human malignant melanoma.

Adult↗
PubMed1979

Physical association of histocompatibility antigens and tumor-associated antigens on the surface of murine lymphoma cells.

Serologic and immunochemical techniques were used to characterize plasma membrane antigens of the murine lymphoma 6C3HED. Syngeneic C3H/HeJ anti-6C3HED antisera were prepared and were shown by cytotoxicity, absorption, and immunoprecipitation tests to be specifically reactive with the lymphoma cells. Alloantisera to H-2.23 were found to be unreactive with intact lymphoma cells by cytotoxicity and absorption assays. However, H-2.23 antigens were detectable in tumor cell lysates by inhibition of cytotoxicity and immunoprecipitation. SDS-PAGE electropherograms of immunoprecipitates of radiolabeled tumor cell extracts obtained with anti-6C3HED and anti-H2.23 antisera were essentially identical; proteins with Mr of approximately 70,000, 45,000, and 12,000 were apparent in both. An immuno-adsorbent of insolubilized anti-6C3HED removed H-2.23 antigens detectable in lymphoma extracts, but had no effect on H-2.23 antigens in normal splenocyte extracts. These data indicate that H-2.23 and TAA are physically associated on 6C3HED cells.

Animals↗
PubMed1978

Murine Ia and human DR antigens: homology of amino-terminal sequences.

Murine Ia and human DR antigens were isolated and purified by immunoprecipitation and sodium dodecyl sulfate/polyacrylamide gel electrophoresis with allo- and xenoantisera, respectively. The I-A subregion antigen consists of two chains, designated Aalpha and Abeta, with molecular weights of 35,000 and 26,000, respectively. The I-C subregion antigen likewise consists of two chains, designated Calpha and Cbeta, with molecular weights of 32,000 and 29,000, respectively. Under nonreducing conditions, the Cbeta chain migrates appreciably more rapidly on sodium dodecyl sulfate/polyacrylamide gels than the reduced Cbeta chain, reflecting the presence of an intrachain disulfide bond. The human DR antigen is also a two-chain unit and contains DRalpha and DRbeta components with molecular weights of 34,000 and 28,000, respectively. The DRbeta chain migrates more rapidly before reduction than afterward, like the murine Cbeta chain. The DRbeta and Cbeta chains are also strikingly homologous if a single amino acid shift is imposed on one of those chains. Thus, human DR antigens strongly resemble the murine I-C subregion antigens.

Amino Acid Sequence↗
PubMed1978

Continuous production of carcinoembryonic antigen in hollow fiber cell culture units: brief communication.

A line of cultured cells derived from a primary human adenocarcinoma of the colon was grown in the extracapillary spaces of hollow fiber tissue culture units in the absence of serum components of high molecular weight (greater than 10,000). The cells were capable of producing more than 30 microgram of carcinoembryonic antigen (CEA) per day, provided that the extracapillary fluid was changed frequently. The concanavalin-A binding and molecular sieve chromatography properties of the tissue culture-derived CEA were similar to those of CEA isolated from metastatic colon cancer tissue.

Adenocarcinoma↗
PubMed1978

Purification and immunologic evaluation of human melnoma-associated antigens.

Melanoma-associated antigens (MAA) were isolated and their functional immunologic properties were evaluated. Spent fetal calf serum-free culture media and 3-m KCI extracts of cultured human melanoma cells grown in this medium were used as antigen sources. Ultracentrifugal flotation on KBr was used to separate MAA and HLA antigens present in the extracts or spent culture media; thus interference by histocompatibility antigens was prevented in subsequent tests of tumor antigenic activity. MAA purified in this manner retained their immunologic functions as evidenced by their ability to produce delayed cutaneous hypersensitivity reactions in patients with melanoma, specifically combine with antimelanoma xenoantibody, and elicit production of functionally specific xenoantibody. Possible structural differences between HLA antigens and MAA were considered in evaluation of the data.

Animals↗
PubMed1978

Serologic and immunochemical characterization of HLA-A9 xenoantisera.

The specificity of A9 antiserum produced in rabbits immunized with high density lipoprotein-associated HLA-A9 from serum was investigated by using serologic and immunochemical approaches. After suitable absorption, the xenoantiserum No. 2958 is monospecific for A9 antigens in direct cytotoxic test. Data from lysostrip experiments and from blocking of cytotoxicity with Fab2 fragments indicate that the A9 xenoantiserum No. 2958 react with the same or closely associated antigenic structures recognized by A9 alloantisera. Immunoprecipitates obtained with the specific xenoantiserum No. 2958 and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis contained only proteins of the size of detergent-solubilized HLA and beta2-microglobulin (45,000 and 12,000 m.w.). Immunodepletion experiments indicated that the precipitation was mediated by antibodies directed to the heavy chain, and not the light chain of the complex. These results indicate that monospecific HLA-A9 xenoantisera have the same discriminatory capacity of alloantisera and can be useful for the serologic and immunochemical characterization of HLA antigens.

Absorption↗
PubMed1977

Expression of histocompatibility (HLA) antigens on tumor cells and normal cells from patients with melanoma.

The expression of HLA antigens and beta2-microglobulin (beta2-mu) on cultured melanoma cells originated from 11 patients has been quantitated and compared with that on fibroblasts and cultured human lymphoid cells originated from the same patients. No qualitative or quantitative difference was detected with the exception of one melanoma line. HLA antigens were also quantitated in sera from melanoma patients: two sera reacted with anti-HLA-B7 antibodies although this specificity was not expressed on lymphocytes from whom the sera were obtained. A technique to quantitate HLA antigens on cells developed in the course of this study is described.

Cell Membrane↗
PubMed1977

Semi-automatic solid-phase radioimmunoassay for carcinoembryonic antigen.

A solid phase, double antibody radioimmunoassay has been semi-automated for the quantitation of carcinoembryonic antigens. Sepharose-bound rabbit anti-goat IgG immunoglobulin was used as the second antibody, reactions were carried out in 96-well microtiter plates, and samples processing (filtration and washing) was accomplished with the aid of a 24-sample harvester.

Carcinoembryonic Antigen↗
PubMed1977

Immunogenicity of HLA antigens purified from serum.

The immunogenic properties of HLA-A9 antigens isolated from serum have been evaluated. A9 antigens at various stages of purification can elicit the formation of cytotoxic antibodies which become operationally specific to A9 either after absorption of the xenoantisera with cultured human lymphoid cells or human red blood cells, or after dilution of xenoantisera with human serum. A9 xenoantisera do no affect mixed lymphocyte reactions between allogeneic lymphocytes carrying A9, suggesting that coating of antigens of the A locus does not impair the functional activity of lymphocytes in the mixed lymphocyte reaction.

Animals↗
PubMed1977

Immunogenicity of human B cell antigens solubilized from cultured human lymphoid cells.

Antigens solubilized from culured human lymphoid cells WI-L2 and RPMI 1788 were partially purified by ultracentrifugation on a KBr gradient. These antigens injected into rabbits produced xenoantibodies which after absorption with melanoma cells became specific to B cell antigens. Three such xenoantisera were submitted to the Second Histocompatibility Workshop of the Americas and reacted much like alloantisera to B cell antigens against a large panel of B peripheral lymphocytes and cells from patients with chronic lymphocytic leukemia. Xenoantisera to B cell antigens inhibited the mixed lymphocyte reaction, but did not affect the mitogenic activity of phytohemagglutinin or the functional properties of C3 receptors, monkey red blood cell receptors, or T cell receptors.

Antibodies↗
PubMed1977

Biologic and chemical characterization of HLA antigens in human serum.

HLA antigens of both the A and B loci were shown to be associated with the high density lipoprotein fraction of serum prepared by ultracentrifugal flotation. HLA-A9 antigens were purified 100-fold with essentially complete recovery by a simple procedure of high density lipoprotein preparation involving precipitation with polyanions and ultracentrifugal flotation. The purified lipid-associated antigen was immunogenic since it elicited the formation of cytotoxic xenoantibodies in rabbits. Serum HLA-A9 antigens were found by immunoprecipitation and gel electrophoresis to consist of a 45,000 m.w. heavy chain associated with beta2-microglobulin. The size of the HLA-lipid complex (less than 190,000 m.w.) and of the HLA-deoxycholate complex (less than 102,000 m.w.) suggests that HLA antigens are shed into plasma as a complex of a single HLA molecule and a single beta2-microglobulin chain, associated with boundary lipid.

Antibodies↗