Antigenic and immunogenic properties of membrane proteins solubilized by sodium desoxycholate, papain digestion or high ionic strength

Production of Leukocyte Migration Inhibition Factor by Lymphocytes of Larynx Cancer Patients Stimulated by Laryngeal Carcinoma Solubilized Membrane Antigens

The production of leukocyte migration inhibition factor (LIF) from lymphocytes after stimulation with 3 M KCl soluble tumor and normal mucosa extracts was investigated in 30 patients with laryngeal carcinoma at different development stages and in 30 normal donors. The experiments were performed in heterologous and autologous systems. In heterologous systems 3 M KCl tumor extracts induced LIF production by heterologous lymphocytes from patients in 91 % of the cases, and normal mucosa extracts induced LIF production by heterologous lymphocytes from patients in 73 % of the cases and from normal donors in 90 % of the cases. In autologous systems 3 M KCl tumor extracts induced LIF production by autologous lymphocytes from the same patients in 65 % of the cases, whereas the normal laryngeal mucosa extracts induced LIF production by the same autologous lymphocytes in the 6 % of the cases. The high positivity percentage of the test in heterologous systems could be related to differences in the major histocompatibility complex. The 65 % test positivity in autologous systems using tumor extracts could be related to the presence of tumor associated antigens.

Specific Lif Production in Laryngeal Cancer Patients: Evidence of Suppressor Activity Exerted by Adherent Cells

The specific tumor-induced LIF production in 30 laryngeal cancer patients has been investigated before and after the removal of adherent cells to evaluate the existence of a suppressor activity. LIF production, after challenging lymphocytes with 3 M KCl autologous tumor extracts, was significant in 16 patients and showed a further significant increase after removal of adherent cells. A conversion to significance when the adherent cells were removed was shown in 6 patients, with no previous significant LIF production. These data suggest the existence of a suppressor activity exerted by adherent cells on LIF production in laryngeal cancer patients.

Critical factors for liposome-incorporated tumour-associated antigens to induce protective tumour immunity to SL2 lymphoma cells in mice

Physical and immunogenic properties of reconstituted membranes designed for the presentation of tumour-associated antigens (TAA) to the immune system are described. Proteins and lipids of crude membranes of SL2 murine lymphosarcoma cells were partially solubilized with octylglucoside. Reconstituted membranes, consisting mainly of unilamellar vesicles with a diameter of 0.03-0.15 microns, were formed by detergent removal and were purified by floatation in a discontinuous sucrose gradient to remove non-lipid-bound protein. Subcutaneous immunization of syngeneic mice with reconstituted membranes or with purified reconstituted membranes induced protection against an intraperitoneal challenge with 10(3) viable SL2 cells. Reconstituted membranes were more immunogenic than crude membranes in immunoprotection experiments when compared on the basis of protein dose. Detergent removal was required to obtain an immunogenic presentation form of SL2 membrane antigens and to avoid toxicity associated with the detergent. Reconstitution of SL2 membranes in the presence of exogenous phospholipid slightly increased the fraction of protein that associated with the reconstituted membranes. However, the immunogenicity of the solubilized membrane TAA was not significantly affected by the presence of exogenous phospholipid. The reconstitution procedure described may be useful in identifying membrane factors required for the induction of immune responses against TAA. The versatility of the system may be employed to develop safe alternatives for whole-cell vaccines.

Biochemical and immunological properties of the human carcinoma antigen CAR-5 defined by the monoclonal antibody BD-5

The monoclonal antibody (MAb) BD-5 reacts with an epitope (CAR-5) expressed in 83% of the gastric carcinomas and in 51% of the ductal pancreatic carcinomas. This MAb reacts also with epithelial cells of colorectal mucosa, but does not react at all with normal adult gastric mucosa or normal adult pancreas. We report the biochemical and immunochemical characterization of CAR-5-bearing molecule. The epitope was found to be carried on a mucin of more than 400 kDa with a density of 1.45 g/ml, metabolically labelled with 35S-sulfate, 3H-glucosamine, 3H-mannose and 35S-methionine. Antigenicity survived metaperiodate oxidation and alkalinization, while it was fully destroyed by pronase or papain. Trypsin, although cleaving the molecule, did not affect its antigenic activity. CAR-5 epitope is thus carried on the protein moiety of a sulfo-mucin. On the basis of its biochemical properties, the antigen was purified by a 3-step procedure, consisting of perchloric acid extraction, molecular sieving on Sepharose CL-4B and affinity chromatography on wheat-germ agglutinin coupled to Sepharose 4B. Cross-competition experiments, together with the chemical properties displayed by the different epitopes, clearly indicate that CAR-5 is different from all previously characterized carcinoma-associated determinants. Cross-DDIRMA experiments performed with different "catcher" and "tracer" antibody combinations showed that CAR-5 epitope may be expressed on the same mucin bearing CA 19-9, MOv2, DU-PAN-2, Lewisa and Lewisb epitopes.

Solubilization of human sperm antigens

Various methods of solubilization of human sperm antigens were compared by testing the sperm extracts against rabbit antihuman spermatozoa immune serums with double immunodiffusion and rocket immunoelectrophoresis. Marked differences were found in the protein contents and the SDS-PAGE protein patterns of the extracts. Lithium diiodosalicylate was the most efficient in solubilizing the sperm proteins and in preserving their antigenicity. Nonionic detergents also gave, either alone or combined to sonification and 1.0 M KCl, 24-28 clearly discernible protein bands and several different immunoprecipitates. Ionic detergents deoxycholate and cetylpyridinium chloride solubilized a high yield of proteins, but their antigenity was poor.

Noncytolytic extraction of cell surface antigens using butanol

Incubation of viable tumor cells in single-phase aqueous solutions of 1-butanol releases a subset of peripherally-associated membrane proteins. Among the extracted components are tumor-specific and tumor-associated antigens of several human and experimental neoplasms. The extraction technique is noncytolytic: extracted cells remain viable and proliferate both in vitro and in vivo. Examination of the denuded cells has elucidated several important differences in cell-surface phenotype that have proved useful in studying the biology of such diverse systems as cellular communications and the mechanisms of hematogenous metastasis. It is anticipated that noncytolytic butanol extraction will continue to prove a powerful approach for the isolation and characterization of a variety of cell-surface antigens.

Isolation of a tumor-associated transplantation antigen (TATA) from an SV40-induced sarcoma. Resemblance to the TATA of chemically induced neoplasms

A tumor rejection antigen (TATA), obtained from the cytosol of a BALB/c mKSA sarcoma induced by SV40 virus, has been partially purified. This partially purified antigen is strikingly immunogenic against mKSA, providing more than 90% inhibition of growth at levels of 10-30 micrograms. This antigen preparation does not protect against challenge with another SV40-induced BALB/c sarcoma VLM which, however, shares a group-specific TATA with mKSA. The antigen also does not immunize against challenge with the methylcholanthrene-induced sarcomas of BALB/c mice, Meth A, CI-4, CII-7 and CII-10, each of which has its own unique TATA. Binding assays, using ELISA, failed to detect any SV40 antigen in the antigen preparation despite the fact that the large T antigen of SV40 (or fragments of it) constitutes the immunodominant TATA of mKSA.

Generation of crossreacting tumor antigens in ascitic derivatives from murine methylcholanthrene-induced sarcomas

Sarcomas induced by the chemical carcinogen 3-methyl-cholanthrene (MC) in pedigreed BALB/c strain mice were studied for the existence and characteristics of tumor-specific antigens that induce protective immune defenses in syngeneic mice (TATA). It was found that each of the neoplasms expressed a unique immunogenicity that was stable and heritable over a period of 125 transfers in vivo. Common or crossreacting TATA were not observed. When converted to an ascitic form, two of these sarcomas, CII-7 and CII-10, were found to be crossreactive, presumably sharing TATA with each other and with the MC-induced sarcoma Meth A. Two other neoplasms converted to the ascitic form, however, retained their unique TATA. Although the precise nature of unique and crossreacting TATA is not known, it is hoped that recent investigations in the purification of TATA of chemically induced neoplasms will shed light on the mechanisms responsible for the diversity of tumor-specific antigens.

Purified membrane fractions from mammary tumor cells elicit biological reactivity in in vitro cell-mediated immune reactions

Lithium chloride (LiCl) aggregation followed by centrifugation through a sucrose step gradient was used to obtain purified plasma membranes from two sublines of mouse mammary adenocarcinoma. These two tumor lines were chemically induced by treatment of a hyperplastic nodule with 7,12-dimethylbenzanthracene (DMBA). One line, D1-DMBA-3, has been found to be immunogenic to the host of origin, while the other, D1-DMBA-2, does not elicit specific tumor immunity as previously tested in in vivo and in vitro immune reactions. The purified membrane fractions were assayed for protein, DNA and sialic acid content as well as enzymatic markers of membrane purity. When tested in blastogenesis and cytotoxicity reactions, membrane-containing fractions from the D1-DMBA-3 immunogenic tumor were found to be stimulatory to spleen cells of D1-DMBA-3 tumor bearers over a ten-fold protein concentration. Spleen cells from normal mice do not respond in these reactions to the various tumor fractions. No reactivity was observed when non-membrane-containing preparations were used as stimuli in the cell-mediated immune reactions. The specificity of these reactivities was further demonstrated by the lack of responses when fractions from the non-immunogenic D1-DMBA-2 tumor were tested in parallel in our in vitro assays. The data presented indicate that the procedure employed is useful for the isolation of membrane-associated, tumor-specific antigens which can be easily quantitated and still retain biological activity in in vitro tests of cell-mediated immunity.

Solubilization and partial characterization of a tumor-rejection antigen from an ultraviolet light-induced murine tumor

Tumor rejection antigen (TRA) of an ultraviolet-light-induced murine skin tumor was solubilized, fractionated and partially characterized. Subcellular fractions were prepared by differential centrifugation of tumor cells that had been ruptured via nitrogen cavitation. Only the 110,000-g membrane fraction induced significant tumor protection, as determined by in vivo immunization and challenge assays. Extraction of the membrane fraction with 3 M KCI resulted in solubilization of material that could induce in vivo tumor-rejection immunity. Both the membrane fraction and soluble extract had a limited effective dose range. The KCI extract was separated on a Sepharose, CL-6B column in the presence of 6 M guanidine-HCI. Only one of five fraction pools (molecular weight range of 76,000-127,000 daltons) was immunogenic. It contained at least eight protein bands by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), but no lipid components. This immunogenic Sepharose fraction was chromatographed on a Sephadex G-150 column. Each of the four Sephadex fraction pools was immunogenic. One protein component was common to each of those fractions. It migrated as a single 76,000-dalton band on SDS-PAGE and contained [14C]-leucine and [3H]-glucosamine that had been incorporated during cell growth. These results suggest that the TRA of this tumor is a 76,000-dalton glycoprotein.

Immunochemical purification of probe-labeled plasma membrane proteins: an approach to the molecular anatomy of the cell surface

The probe 2,4,6-trinitrobenzene sodium sulfonate may be used under appropriate conditions for selective labeling of plasma membrane proteins exposed at the outer cell surface. Labeled proteins, solubilized by detergents, can be purified by reverse immunoadsorption using antiprobe antibodies covalently linked to Sepharose 4B. This method has been applied to an investigation of the outer cell surface structure of chicken embryo and hamster fibroblasts. Coelectrophoresis in sodium dodecyl sulfate-polyacrylamide gels of probe-labeled membrane proteins purified from baby hamster kidney fibroblasts have shown that 7 major protein groups of different molecular weight are exposed on both control and Rous sarcoma or polyoma virus-transformed cells. Moreover, the transformed cells display a nonvirion component of 80--100 k daltons that is not labeled by the probe in normal cells. In fibroblasts transformed by a temperature sensitive Rous sarcoma virus mutant, that transforms at 37 degrees C but not at 41 degrees C, the expression of this component is related to the expression of the transformed phenotype.

Immunochemical studies of infectious mononucleosis. VI. a radioimmunoassay for the detection of infectious mononucleosis heterophile antibody and antigen

The coated-tube method of solid-phase radioimmunoassay has been adapted to the detection of heterophile antibodies and antigens of infectious mononucleosis. Disposable plastic hemagglutination trays were coated with purified glycoprotein from horse erythrocytes and the subsequent uptake of antibody from test sera was detected by radio-iodinated horse erythrocyte glycoprotein. In a preliminary survey of sera from patients with infectious mononucleosis and sera from controls, the assay proved highly sensitive and specific. The test system was also useful in a competitive binding assay for immunochemical studies of glycoproteins from other heterophile antigen-positive species.

A solid-state competitive binding radioimmunoassay for measurement of antigens solubilized from membranes

A sensitive, solid-state, competitive radio immunological method for quantitation of antigens solubilized from membranes is described. This method is based on the measurement of the displacing activity of unknown samples of antigens on 125I-labelled antibodies bound to antigen-coated polyvinyl microtitre wells.