Carbohydrates as a tool for oriented immobilization of antigens and antibodies

A biospecific sorbent for the isolation of ovalbumin antibodies was prepared by coupling of ovalbumin via its periodate-oxidized carbohydrate moiety to bead cellulose modified with adipic acid dihydrazide. The anti-ovalbumin IgG fraction isolated on this sorbent from immune rabbit serum contained only antibodies against protein determinants of ovalbumin. Thus, when these IgG were immobilized through their carbohydrate moieties to cellulose beads it became possible to prepare a biospecific sorbent for concanavalin A by oriented adsorption of ovalbumin. Ovalbumin was specifically adsorbed via its protein moiety and its carbohydrate part remained free for interaction with concanavalin A.

Delipidation of alpha 1-acid glycoprotein. Propranolol binding to this glycoprotein and its modification by extracted material and exogenous lipids

Propranolol binding to human alpha 1-acid glycoprotein (AAG) delipidated by two methods is described. Commercial AAG (99% pure) was either precipitated by ethanol-acetone and then washed by ether, or it was precipitated by ethanol. Binding capacity was quantified by the product n x Ka where n denotes the number of binding sites and Ka the association constant (M-1). Propranolol binding to nondelipidated AAG (n x Ka = 0.113 +/- 0.013 microM-1) was clearly increased after precipitation by ethanol-acetone (n x Ka = 0.386 +/- 0.109 microM-1) or precipitation by ethanol (n x Ka = 0.312 +/- 0.096 microM-1). Binding capacity potentiation cannot be due to modification of AAG microheterogeneity forms, as two-dimensional gel electrophoresis pattern of AAG in presence of concanavalin A was not altered after both methods. Recombination of precipitated AAGs with supernatant dry residue resulted in the abrogation of observed potentiation. Moreover, addition of a polar lipid, linoleic acid, (from 30 to 300 microM) strongly inhibited propranolol binding. These results indicated that glycoprotein precipitation by ethanol provided a simple method to further study binding inhibitors associated with isolated AAG.

Crosslinking of concanavalin A with glutaraldehyde

Crosslinking of Concanavalin A with low concentrations of glutaraldehyde gives a mixture of products. A specific product having about 66% of the biological activity of the native molecule was characterized. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed the presence of monomers, dimers, trimers, tetramers, and a small amount of pentamers as products. The presence of alpha-methyl mannoside during crosslinking changed the nature of the products, yielding a product retaining 80% of the biological activity. The crosslinked products showed greater stability than the native molecule at alkaline pH. However, the greatest stability under alkaline conditions was shown by the native molecule itself where alpha-methyl mannoside was present.

Determination of chemical properties of individual histidine and tyrosine residues of concanavalin A by competitive labeling with 1-fluoro-2,4-dinitrobenzene

A selective peptide-mapping procedure was devised to purify peptides containing histidine or tyrosine residues from proteolytic digests of concanavalin A (Con A). The protein was modified with maleic anhydride followed by 1-fluoro-2,4-dinitrobenzene (Dnp-F) and then digested with thermolysin. The resulting labeled peptides were separated by high-performance liquid chromatography, and the Dnp-histidine and Dnp-tyrosine peptides were identified by their spectral characteristics. From their amino acid compositions, the labeled peptides could all be assigned within the known sequence. Peptides representing five of the six histidines and all seven tyrosines were obtained. With the same peptide-mapping procedure, the chemical properties (pK and reactivity) of these residues were determined. Samples of concanavalin A at various pH values were labeled with trace amounts of [3H]Dnp-F, in the presence of Gln-Gly as an internal standard. To each sample was added an aliquot of a mixture of [14C]Dnp-Gln-Gly and [14C]Dnp-maleyl-Con A. Portions of each sample were removed, [14C]Dnp-Ala-Ala and epsilon-[14C]Dnp-lysine were added, and the mixtures were hydrolyzed. The various Dnp amino acid derivatives were purified by HPLC. The remainder of each [3H]Dnp sample was maleylated, dinitrophenylated, and digested with thermolysin and separated by HPLC as above. From the 3H/14C ratios of the Dnp amino acid derivatives and the Dnp peptides relative to the ratio of the internal standard, pK and reactivity data were obtained for (a) the average behavior of the lysine, histidine, and tyrosine residues and (b) the individual behavior of the N-terminal alanine residue and the five histidine and seven tyrosine residues in the protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of a concanavalin A supernatant-derived idiotype-specific T helper cell factor

We have previously demonstrated the requirement of two T helper (Th) populations for the expression of plaque-forming cells (PFC) that bear the dominant cross-reactive idiotype (CRI) associated with the phenyltrimethylammonium (TMA) response (1). In addition to the classic major histocompatibility complex-restricted Th cell, the response was also dependent upon the so-called second order Th2 population, which binds to idiotypic determinants, is carrier specific, but does not require hapten linked to carrier for function. This cell type can be replaced by supernatant (Sn) media from concanavalin A (Con A)-stimulated naive spleen cells. This report involves the study of the Con A Sn derived factor(s) responsible for the expression of CRI bearing PFC populations. When the Brucella abortus (BA)-trinitrophenol (TNP) conjugated antigen is added to TNP-ovalbumin-primed A/J-derived spleen cells in culture, anti-TNP PFC are generated of which only less than or equal to 5% bear the CRI normally associated with anti-TMA antibodies. Upon addition of Con A Sn, the total number of generated anti-TNP PFC doubles, whereas the percentage and number of CRI+ PFC increases approximately eightfold to 10-fold. The factor(s) responsible for this activity are T cell derived, bear Jk serologic determinants, and can be detected in the Sn as early as 4 hr after Con A stimulation. The material appears to be late acting, because it can augment the CRI+ anti-TNP response when added as late as 24 hr before termination of the cultures. In addition, the factor(s) can be bound to and eluted from CRI+ anti-TMA and anti-TNP monoclonal antibodies coupled to Sepharose 4B beads, but not from their CRI- counterparts (i.e., CRI- anti-TMA and anti-TNP antibodies), nor from A/J normal mouse immunoglobulin-coupled beads. Most interestingly, the factor(s) also bind to and can be eluted from the TMA ligand coupled to Sepharose 4B, but not from TNP-Sepharose conjugates. All of these results are consistent with the support the contention that the factor(s) is derived from a Th2-like subpopulation. As assayed by standard protocols, the isolated material contains no T cell replacing factor, interleukin 2, or B cell growth factor activity.

Induction of suppressor cells, interleukin-2 production and mitogenesis with monomeric concanavalin A: different actions of tetrameric and monomeric concanavalin A

The ability of a photoalkylated monomeric concanavalin A (Con A) derivative to induce mitogenesis, interleukin-2 (IL-2) production and suppressor cells in murine spleen cell cultures has been compared with the activity of native, tetrameric Con A. The monomeric derivative was prepared by photochemically induced alkylation of tryptophan residues of tetravalent Con A in the presence of chloroacetamide followed by sizing chromatography [Tanaka et al. (1981) J. Biochem. 89, 1643-1646]. The monomeric derivative appeared to display less mitogenic activity than the tetramer and was also less effective in inducing IL-2 production. No difference was detected between the monomeric and tetrameric forms of Con A in inducing suppressor cells. The data suggest that cross-linking and bridging via sugar-binding sites, while potentiating mitogenesis and IL-2 production, had little effect on suppressor cell induction.

Stimulated rat T cell-derived inhibitory factor for cellular DNA synthesis (STIF). III. Effect on cell proliferation and immune responses

Stimulated T cell-derived inhibitory factor for cellular DNA synthesis (STIF), a lymphokine produced from concanavalin A (Con A)-stimulated rat suppressor T cells, was examined for its inhibitory effect on various cultured cells and on in vitro immune reactions. STIF could inhibit the DNA synthesis of a variety of normal and neoplastic cells from rats, mice, and humans in a dose-dependent fashion. Kinetics studies revealed that STIF selectively inhibited cellular DNA synthesis after incubation for 12 hr, but after 36 hr, it also inhibited RNA and protein syntheses. The inhibited cellular DNA synthesis by 12-hr incubation with STIF was recovered after culturing the cells in STIF-free medium. The inhibitory effect of STIF on the DNA synthesis was not blocked by addition of a sugar (alpha-methyl-D-mannoside, N-acetyl-D-glucosamine, N-acetyl-D-galactosamine, L-fucose, or L-rhamnose) in culture, as determined by using rat bone marrow cells. STIF inhibited proliferative responses of rat lymphocytes to T cell mitogens, Con A and phytohemagglutinin, and a B cell mitogen, lipopolysaccharide, as well as IL 2-dependent growth of cloned T572 cells. It could also inhibit both blastogenesis and cytotoxic T cell generation in allogeneic mixed lymphocyte reaction. The release of IL 2 from Con A-stimulated T cells was also inhibited by the added STIF in culture, as demonstrated from the finding that IL 2 activity was not detected in the supernatants even after an anion-exchange column chromatography. These results indicate that STIF could inhibit cellular DNA synthesis in a species-unrestricted manner and thus inhibits the proliferation of various normal and neoplastic cells, and that it could also inhibit lectin- or IL 2-dependent T cell proliferation as well as IL 2 production from T cells in in vitro immune reactions.

Toxofactor associated with Toxoplasma gondii infection is toxic and teratogenic to mice

A toxin associated with Toxoplasma gondii infection was obtained from the trophozoites and culture medium used to propagate the parasite in cell cultures. The toxin, named Toxofactor (TF), administered parenterally or nonparenterally in adult mice, produces transient symptoms of lethargy, ruffled fur, and body weight loss. Organ changes which accompanied the outward symptoms included hepatosplenomegaly and involuted thymus. TF activity was detected in extracts of the blood, peritoneal fluid, liver, and spleen of infected mice. Severe damage to embryonal and fetal development was induced when TF was administered during pregnancy. Resorption, abortion, and congenital abnormalities were produced, dependent upon the stage of development at the time of exposure. Adult mice which had reacted to and recovered from an initial intraperitoneal injection to TF were protected against a secondary challenge from TF. Fetal development was also protected from damage when TF was used to challenge adults previously exposed to TF. Mouse and rabbit anti-TF sera neutralized TF activity in the adult. In no instance did control mice show any deleterious effect when exposed to soluble cell lysate from the uninfected cell line (BHK-21) used to propagate the organism plus the used medium from these same uninfected cells. TF activity was not attributed to bacterial, myocoplasmal, or viral contamination. TF toxic activity is labile to elevated temperature and high or low pH, which also destroy its protective properties. TF activity was sensitive to trypsin and was obtained in the elution fraction (alpha-methyl-D-mannoside) from affinity chromatography (concanavalin A-Sepharose 4B). Ultrafiltration indicated the molecular weight to be between 50,000 and 100,000. TF, apparently a glycoprotein, was quantitated for activity by a weight loss assay. A unit of activity was defined as the minimum quantity of TF (highest dilution) which produced at least a 10% average body weight loss in adult Nya:NYLAR female mice between days 7 and 12 post-intraperitoneal injection.

Enhancement of macrophage Fc-dependent phagocytosis by resident thymocytes: effect of a unique heat-stable lymphokine

Lymphocytes, activated by lectins or specific antigens, have been shown to enhance macrophage phagocytosis through the elaboration of a heat-labile soluble factor(s). Recent evidence from our laboratory revealed that resident (nonactivated) murine thymocytes and splenic lymphocytes increase peritoneal macrophage glucose metabolism through the elaboration of a heat-stable soluble factor(s). Therefore, we investigated the effect of resident lymphocyte subpopulations on macrophage Fc-dependent phagocytosis. Thioglycollate-elicited and resident peritoneal macrophages from BALB/c mice were cultured in serum-free media with syngeneic resident thymocytes or splenic T lymphocytes. Macrophage Fc-dependent phagocytosis was assayed by measuring the ingestion of 51CrSHEA. After 4 days in vitro, resident thymocytes produced a mean 160 (+/- 31) and 136% (+/- 22) increase in Fc-dependent phagocytosis by thioglycollate-elicited (thio-macrophages) and resident peritoneal macrophages, respectively. Splenic T lymphocytes increased thio-macrophage phagocytosis by 112% (+/- 41) under similar conditions. Macrophage Fc-dependent phagocytosis was increased after 24 hr of co-culture by supernatant derived from resident thymocytes and could be further enhanced by supernatant from Con A-activated thymocytes. Supernatant from guinea pig embryo fibroblasts did not increase macrophage phagocytosis. The soluble factor(s) was produced by resident thymocytes after 24 hr of preculture. This factor was active despite heating at 100 degrees C for 30 min whereas the effect of Con A-activated thymocyte supernatant was heat-labile. The stimulatory effect of resident thymocyte supernatant was not observed when the macrophages and supernatant were cultured in 2% FCS. In contrast to the factor(s) produced by resident thymocytes, the factor(s) in FCS that increased phagocytosis was heat-labile. These data suggest thymocytes and splenic T lymphocytes promote macrophage Fc-dependent phagocytosis in the absence of antigenic or lectin stimulation. This previously unrecognized effect of resident thymocytes is due to a unique heat-stable soluble factor(s) that is concealed in the presence of serum.

A high performance liquid chromatography assay for the rapid analysis of the subunit content of concanavalin A

A high performance liquid chromatography system is described which provides a rapid and convenient assay for the relative amounts of intact (26000 dalton) and fragmented (14000 and 12000 dalton) subunits present in preparations of concanavalin A. Analyses were performed on an HPLC size exclusion column using either 8M urea or 6M guanidine hydrochloride as denaturing eluents. The efficiency and resolving power of this technique were confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. This HPLC assay facilitated the monitoring of the purification of concanavalin A to prepare a homogeneous preparation necessary for its biological evaluation.

Synthetic glycosyl polymers in isolation, characterization and immobilization of lectins

A review is given on preparative procedures and practical applications in the field of lectins of two types of synthetic polymers: (1) Glycosyl polyacrylamide derivatives - insoluble (cross-linked) and water-soluble (linear) - that are obtained by copolymerization of alkenyl glycosides and acrylamide, and (2) glycosyloxyethyl dimethacrylate copolymers prepared by glycosylation of the commercially available macroporous glycol methacrylate copolymer, Separon. Both types of copolymers are efficient affinity carriers for isolation of lectins. Separon derivatives can be used after partial periodate oxidation of the glycosyl groups for covalent coupling of lectins. Affinity carriers thus obtained can be employed in separation and purification of glycoproteins and other glycosylated macromolecules. Soluble glycosyl polyacrylamide derivatives are useful in precipitation of lectins and, in general, as synthetic model substances for studying interactions of lectins with sugar ligands.

Preparation of T cell growth factor free from interferon and factors stimulating hemopoietic cells and mast cells

A simple two-step method involving ammonium sulfate precipitation followed by hydrophobic chromatography is described for the separation of T cell growth factor (TCGF) from a number of other factors contained in medium conditioned by concanavalin A-stimulated spleen cells. Thus, granulocyte-macrophage colony-stimulating factor, P cell-stimulating activity, pluripotential stem cell-supporting activity and interferon activity were not detected in TCGF partially purified by these steps. T cell-replacing factor co-purified with TCGF. Macrophage activity factor (MAF) co-purified with TCGF, but the ratio of MAF to TCGF activities was reduced more than 20-fold relative to that in crude conditioned medium. All of the factors were present in the 50-80% saturated ammonium sulfate fraction, however, levels of concanavalin A were reduced by 98% in this step. TCGF, separated in this way from these other regulatory factors will be useful in experiments analyzing the actions of TCGF on mixed populations of cells.

[The in vitro proliferative response of human peripheral blood lymphocytes stimulated with purified concanavalin A and the analysis of subpopulations of T-cells (author's transl)]

Human peripheral blood lymphocytes (PBL) were separated from anticoagulated peripheral blood using the Ficoll-Conraxin-L gradient technique, and were cultured with various concentrations of highly purified concanavalin A (Con A (F3)). Tritiated thymidine incorporation in these cultures was measured. PBL responded well to low doses of Con A (F3) and high doses of Con A (F3), and the dose-response curve to Con A (F3) of PBL seemed to show that bimodal proliferative response with a notch or a peak at 5--6 micrograms/ml of Con A (F3) and the other peak at the higher doses of Con A (F3). As it has been well known that E-rosette-forming cells (E-RFC) in human peripheral blood can be subdivided into two T-cell subpopulations on the basis of their relative affinity for sheep red blood cell (SRBC), we have examined how these T-cell subpopulations could responded to Con A (F3) at varying concentrations. We found that "Low-affinity E-RFC" could be optimally stimulated by Con A (F3) at 5--6 micrograms/ml, while "High-affinity E-RFC" at 8--12 micrograms/ml. 3H-thymidine incorporation of high-affinity E-RFC was strikingly increased at low doses of Con A (F3) when low-affinity E-RFC and high-affinity E-RFC were mixed at 25: 75 ratio, and the dose-response curve was very similar to that of PBL. Moreover when monocytes were added to high affinity E-RFC and the mixture was cultured, the doses-response curve was elevated at low doses of Con A (F3), but the dose-response curve was similar to that of high-affinity E-RFC and different from that of low-affinity E-RFC. Our results suggest that low-affinity E-RFC that has the capacity to respond optimally to Con A (F3) at 5--6 micrograms/ml in the in vitro proliferative response has the important effect upon the in vitro proliferative response of PBL to low doses of Con A (F3).

Preparation of homogeneous concanavalin A

Concanavalin A (Con A), obtained either commercially or by affinity chromatography, was further purified by incubating at 6-8 hr at pH 3.0-3.2 in 1 M NaCl, 0.08 M glycine and 3 mM each Ca2+ and Mn+2, heat treating at 45 degrees C for 2 hr and centrifuging. The supernatant was neutralized to pH 5 and stored in the cold. Te overall yield was 70-80%. Some of the properties of Con A at pH 5 are: The absorption coefficient of a l g/dl solution is 13.7 at 280 nm; the mean residue ellipticity at 224.5 nm is -9,300 degrees to -9,800 degrees; by sedimentation equilibrium, its molecular weight is 53,000 between pH 3.0 and pH 5.2. Con A solutions standing at room temperature at pH 7 for ten days lose through precipitation only 5-8% of the protein in 0.2 M NaCl and 15% of the protein in 0.1 M NaCl. In the solution conditions of SDS and urea-SDS gels, Con A not only unfolds slowly and incompletely, but it also forms high molecular weight aggregates. Thus, electrophoresis of Con a in such gels is unsuitable for tests of homogeneity. However, as judged by sedimentation equilibrium in 6.5 M quanidine at pH 8.1, purified Con A was monodisperse.

Studies on lectins. XLIX. The use of glycosyl derivatives of Dextran T-500 for affinity electrophoresis of lectins

p-Aminophenyl glycosides and glycosylamines were coupled to periodate oxidized Dextran T-500 either directly or through an epsilon-aminocaproic acid spacer. The new glycosylated derivatives of dextran specifically precipitate lectins having the appropriate carbohydrate specificity, and thus were used in the preparation of affinity gels for affinity electrophoresis of lectins. The apparent strength of interaction of several lectins with carbohydrate residues immobilized in this way was less than with carbohydrates immobilized in O-glycosyl polyacrylamide copolymers. The presence of epsilon-aminocaproic spacer had no effect on the strength of interaction. The advantages of this type of macromolecular derivative of the ligand for affinity electrophoresis and some differences between the glycosylated dextrans and O-glycosyl polyacrylamide copolymers are discussed. Dextrans containing bound p-aminophenyl alpha-D-mannopyranoside and p-aminophenyl alpha-D-glucopyranoside were used to study the binding properties of concanavalin A and the lectin from Lathyrus sativus seeds. For the investigation of interaction of lectins from Ricinus communis and Glycine soja seeds, dextran derivatives containing bound p-aminophenyl alpha- and beta-D-galactopyranosides and alpha- and beta-D-galactopyranosylamines were used.

In vitro growth of murine T cells. III. Method for separation of T cell growth factor (TCGF) from concanavalin A and biological activity of the resulting TCGF

T cell growth factor (TCGF) resulting from the incubation of murine splenocytes with concanavalin A (Con A) has been partially purified and separated from Con A. Sequential application of 50-70% saturated ammonium sulfate precipitation and G-100 gel filtration chromatography has resulted in a 300-fold purification of TCGF with a 60% yield. 99.99% of Con A has been removed from the TCGF by these steps. TCGF exists in two molecular weight forms of about 50,000 and 25,000 daltons. TCGF activity is degradable by trypsin digestion and is stable at 56 degrees C for 30 min, but is inactivated by heating at 80 degrees C. Lymphoid cells activated by either Con A or allogeneic in vitro sensitization will grow in TCGF free of Con A but fresh splenocytes will not grow in the absence of Con A, implying a need for prior activation before TCGF sustained growth of T cells can be achieved.