Production and purification of Fab' fragments from chicken egg yolk immunoglobulin Y (IgY)

Different involvement for aldolase isoenzymes in kidney glucose metabolism: aldolase B but not aldolase A colocalizes and forms a complex with FBPase

The expression of aldolase A and B isoenzyme transcripts was confirmed by RT-PCR in rat kidney and their cell distribution was compared with characteristic enzymes of the gluconeogenic and glycolytic metabolic pathway: fructose-1,6-bisphosphatase (FBPase), phosphoenol pyruvate carboxykinase (PEPCK), and pyruvate kinase (PK). We detected aldolase A isoenzyme in the thin limb and collecting ducts of the medulla and in the distal tubules and glomerula of the cortex. The same pattern of distribution was found for PK, but not for aldolase B, PEPCK, and FBPase. In addition, co-localization studies confirmed that aldolase B, FBPase, and PEPCK are expressed in the same proximal cells. This segregated cell distribution of aldolase A and B with key glycolytic and gluconeogenic enzymes, respectively, suggests that these aldolase isoenzymes participate in different metabolic pathways. In order to test if FBPase interacts with aldolase B, FBPase was immobilized on agarose and subjected to binding experiments. The results show that only aldolase B is specifically bound to FBPase and that this interaction was specifically disrupted by 60 microM Fru-1,6-P2. These data indicate the presence of a modulated enzyme-enzyme interaction between FBPase and isoenzyme B. They affirm that in kidney, aldolase B specifically participates, along the gluconeogenic pathway and aldolase A in glycolysis.

Snake egg immunoglobulins: biochemical characteristics and adjusted isolation procedure

Transmission of specific immunoglobulins from mothers to their offspring via the egg is a common phenomenon in egg-laying vertebrates but the occurrence of this phenomenon in reptiles, especially in colubrid snakes, has not been proven until recently. Thus, the essential biochemical characteristics of antibodies deposited in eggs of Elaphe guttata (Colubridae, Serpentes) were studied after isolation of the antibody by precipitation and purification by affinity chromatography and gel filtration, with verification by isoelectric focusing and immunoprecipitation. The immunoglobulin deposited in the eggs of colubrid snakes is a singular, non-truncated IgY antibody in a concentration roughly equal to that in the snake's serum. An efficient method to isolate antibody from snake eggs was developed, based on the PEG precipitation technique of avian yolk immunoglobulins; an unsophisticated protocol for the isolation procedure appropriate for reptile eggs is provided.

LRP1B Attenuates the Migration of Smooth Muscle Cells by Reducing Membrane Localization of Urokinase and PDGF Receptors

Objective— Studies on the involvement of low-density lipoprotein receptor relatives (LRs) in atherosclerosis have recently gained new focus because of the specific expression of certain of these receptors in the thickened intima. Here, we show that LRP1B, a member of LRs, modulates the migration of smooth muscle cells (SMCs) by increasing the degradation of membrane receptors, urokinase-type plasminogen activator receptor (uPAR), and platelet-derived growth factor receptor (PDGFR) β.

Methods and Results— Immunohistochemistry showed that LRP1B expression in human coronary arteries is localized to the intimal SMCs near the plaque surface as well as to medial SMCs. LRP1B expression levels in cultured SMCs increase at the late phase of proliferation. Cell surface and internalization assays, in combination with coimmunoprecipitation experiments, showed that LRP1B binds and internalizes uPAR. Metabolic labeling analysis demonstrated that anti-LRP1B IgY decreased the catabolism of uPAR. In addition, the anti-LRP1B antibody raised PDGFRβ protein and PDGFR-mediated phosphorylation levels of ERK1/2. Finally, the anti-LRP1B IgY enhanced the migration and invasion of SMCs in the presence of PDGF-BB.

Conclusions— LRP1B modulates the catabolism of uPAR and PDGFR, affecting the migration of SMCs. This functional characterization of LRP1B opens novel avenues for elucidating the (patho)physiological significance of SMC migration in atheromatous plaques.

Isolation of antigens and antibodies by affinity chromatography

Antibody-antigen binding constants are commonly strong enough for an effective affinity purification of antibodies (by immobilized antigens) or antigens (by immobilized antibodies) to work out a straightforward purification method. A drawback is that antibodies are large protein molecules and subject to denaturation under conditions required for the elution from the complex. Structures of antigens can vary but usually antigens are also equally subject to similar problems. The lability of the components can sometimes make the procedure sophisticated, but usually in all cases it is possible to find a satisfactory approach. In certain cases, specific interactions of the Fc part of antibodies are more facile to exploit for their purification.

Chicken egg yolk antibodies as therapeutics in enteric infectious disease: a review

Passive immunization by oral administration of specific antibodies has been an attractive approach against gastrointestinal (GI) pathogens in both humans and animals. Recently, laying chickens have attracted considerable attention as an alternative source of antibodies for the prevention and treatment of infectious GI diseases. After immunization, the specific antibodies (called IgY) are transported to the egg yolk, from which the IgY then can be separated without sacrificing chickens. A chicken usually lays about 280 eggs in a year, and egg yolk contains 100-150 mg of IgY per yolk, suggesting that more than 40 g of IgY per year can be obtained from each chicken through eggs. IgY is also an alternative to antibiotics for treatment of enteric antibiotic-resistant pathogens. Oral administration of IgY has proved successful for treatment of a variety of GI infections, such as bovine and human rotaviruses, bovine coronavirus, Yersinia ruckeri, enterotoxigenic Escherichia coli, Salmonella spp., Edwardsiella tarda, Staphylococcus, and Pseudomonas. The IgY technology offers great future opportunities for designing prophylactic strategies against infectious GI diseases in humans and animals. However, there is still controversy regarding the stability of IgY through the GI tract. Finding an effective way to protect the antibodies from degradation in the GI tract would open the door for significant advances in IgY technology and nutraceutical applications.

Effect of bursal anti-steroidogenic peptide and immunoglobulin G on neonatal chicken B-lymphocyte proliferation

In attempts to identify antibodies for Bursal Anti-Steroidogenic Peptide (BASP), rabbit serum was observed to reduce phorbol ester-stimulated chicken B-lymphocyte proliferation comparable to BASP. These experiments investigated the effects of IgG on B-lymphocyte proliferation. In Experiment 1, 3% rabbit serum decreased B-lymphocyte proliferation. In Experiment 2, 2 mg/ml of intact rabbit IgG or 0.65 mg/ml of IgG papain digest products, Fab and Fc, decreased B-lymphocyte proliferation. The combination of BASP and either Fab or Fc was observed to have at least an additive anti-proliferative effect. In Experiment 3, 0.01 mg/ml of either rabbit or chicken IgG, or 1.0 mg/ml of rabbit or 0.01 mg/ml of chicken Fab, Fc, and the pepsin digestion product F(ab')(2) was observed to have an anti-proliferative effect. No combined effects of BASP and IgG or IgG digest products were observed for this experiment. In Experiment 4, 12 mg/ml of chicken egg yolk IgG or 1.2 mg/ml Fab was found to suppress B-lymphocyte proliferation. Additionally, an additive effect of 12 mg/ml of IgG with BASP was again observed. The present studies suggest that IgG and its digestion products reduce phorbol-stimulated B-lymphocyte proliferation in vitro and combined treatment with IgG and BASP may have at least an additive anti-proliferative effect on B-lymphocyte proliferation.

Alpha Gal is widely expressed in embryonic porcine stem cells and neural tissue

Fetal porcine neural xenografts are an alternative to human fetal tissue for cell based treatments of a number of neurodegenerative conditions but are currently limited by host immunological rejection. The expression of a major immunological epitope, Galalpha1-3Galbeta1-4GlcNAcbeta-R (alphaGal) was determined on stem cells and primary cells derived from E26 porcine fetal brains. alphaGal was detected on the majority of neural stem cells and cells from primary cell suspensions. The expression of this epitope paralleled the binding of human IgG and IgM to the cells, a binding that was significantly reduced with anti-alphaGal depleted human serum. This study demonstrates that alphaGal expression is extensive in embryonic porcine neural cells and will be of relevance to any clinical trials using this tissue.

Expression of LSLCL, a new C-type lectin, is closely restricted, in bone marrow, to immature neutrophils

In vitro, LSLCL is expressed by numerous myeloid, promyelocytic, and T or B lymphoblastoid cell lines. In vivo, LSLCL is strongly expressed in bone marrow and only faintly in lymphoid organs. We show here that, in bone marrow, LSLCL is detected: (i) concentrated in the cytoplasm of immature neutrophils but not in myeloblasts nor in mature neutrophils, (ii) in extracellular bone marrow fluid. Besides, numerous cDNAs, similar to LSLCL (identity of 93-99%), are found in 'expressed sequence tags' databases from various origins, mostly fetal and undifferentiated tumour tissues. Since LSLCL and various closely related cDNAs are expressed at definite stages of cellular maturation processes, we hypothesize that this class of proteins could play an important role in the control of cellular differentiation.

The ZW10 and Rough Deal checkpoint proteins function together in a large, evolutionarily conserved complex targeted to the kinetochore

The zeste-white 10 (zw10) and rough deal (rod) genes of Drosophila both encode kinetochore components, and mutations in either gene greatly increase the missegregation of sister chromatids during mitosis. Here, we present genetic, cytological and biochemical evidence for a close, evolutionarily conserved relationship between the ROD and ZW10 proteins. We show that the phenotypes caused by disruption of either gene’s function are similar in Drosophila and in C. elegans. No additive effects are observed in zw10; rod double null mutants. In flies, the two proteins always colocalize and, moreover, require each other for their recruitment to the mitotic apparatus. The human ROD and ZW10 homologs also colocalize on HeLa cell kinetochores or kinetochore microtubules throughout most but not all of mitosis. Finally, we show that in both Drosophila and human cells, ROD and ZW10 are in fact physically associated, and in Drosophila these proteins are together constituents of a large (700-900 kDa), soluble macromolecular complex.

Development of highly sensitive enzyme-linked immunosorbent assays for hepatocyte growth factor/scatter factor (HGF/SF): determination of HGF/SF in serum and urine from normal human subjects

A sandwich enzyme-linked immunosorbent assay (ELISA) using rabbit anti-hepatocyte growth factor (HGF) IgG for human HGF, also known as the scatter factor, has previously been developed for determining increases in serum HGF levels in various liver diseases. The sensitivity limit of the ELISA is, however, approximately 0.2 ng/ml sample, and HGF concentrations in about 50% of normal subjects are not accurately measurable by this method, because the mean level of HGF in normal serum is close to the sensitivity limit. In the present study, chicken Fab' from egg yolk anti-HGF immunoglobulin Y and rabbit Fab' from rabbit anti-HGF IgG were conjugated with beta-D-galactosidase. With these conjugates as the second antibodies, we developed two sandwich ELISAs for human HGF and found that the sensitivities were about 20 pg/ml with the former conjugate and 2 pg/ml with the latter. The HGF concentration in sera from 138 normal subjects determined by the ELISA with the rabbit conjugate was 244+/-65 (SD) pg/ml serum, and it correlated very well with the number of leukocytes. Moreover, the ELISA with the rabbit conjugate permitted the determination of HGF levels in urine from normal subjects without first concentrating the sample. The determination of HGF in various biological fluids other than blood and urine by these ELISAs may aid the diagnosis and prognosis of various diseases.

A comparison of fetal and adult porcine islets with regard to Gal alpha (1,3)Gal expression and the role of human immunoglobulins and complement in islet cell cytotoxicity

BACKGROUND

It is still debated whether fetal or adult porcine islets should be the preferred choice for future clinical islet xenotransplantation. Each type of islet preparation has advantages and disadvantages compared with the other. Here we present a direct comparison between fetal and adult porcine islets with regard to Gal alpha(1,3)Gal expression, immunoglobulin and complement binding, and cytotoxicity after exposure to fresh human serum.

METHOD

Islet single cell suspensions were prepared from adult and fetal islets by trypsin digestion. Fluorescein isothiocyanate-conjugated Bandeiraea simplicifolia isolectin B4 (BS-IB4) and affinity-purified chicken anti-Gal alpha(1,3)Gal antibody was used to detect Gal alpha(1,3)Gal expression. Immunoglobulin and complement binding to the islet cells and cytotoxicity for islet cells was compared after incubation with fresh and heat-inactivated human sera and with an immune serum from a diabetic patient who received a fetal porcine islet transplant. Furthermore, two pools of human AB sera were depleted of porcine endothelial cell cytotoxic human anti-Gal alpha(1,3)Gal antibodies by absorption and were used to analyze the effect of Gal alpha(1,3)Gal antibody removal on islet cell cytotoxicity.

RESULTS

Fetal islet cells readily bound both BS-IB4 and the chicken anti-Gal alpha(1,3)Gal antibody. None of 10 adult porcine islet preparations were stained by BS-IB4. In comparison, IgY anti-Gal Ab binding was detected in two of eight adult islet isolations, whereas the other six preparations showed marginal/no binding. After incubation of fetal islet cells with fresh human serum, C3c binding was strongly positive and IgM binding variable, with occasional binding of IgG and no detectable binding of IgA. Adult islet cells were also strongly positive for C3c but did not bind detectable amounts of IgM, IgG, or IgA. Immune sera from a patient who had received fetal porcine islets showed the presence of induced antibodies that bound to fetal islet cells and to porcine peripheral blood lymphocytes, whereas binding to adult islet cells was barely detectable. Fresh human sera showed a high and similar level of complement-mediated lytic activity for both adult islet cells (78+/-22%) and fetal islet cells (75+/-16%). Cytotoxicity for fetal islet cells and peripheral blood lymphocytes was significantly reduced when the corresponding sera were depleted of anti-Gal antibodies before use (P=0.002 and P=0.003, respectively). In contrast, no difference in cytotoxicity for adult islet cells was detected when anti-Gal-depleted human sera were used.

CONCLUSION

Gal alpha(1,3)Gal expression is occasionally detectable on adult porcine islet cells, but not as readily and at a lower level, compared with fetal islet cells. Thus, as porcine fetal islets mature to adult islets, the expression of the Gal alpha(1,3)Gal epitope gradually diminishes. Consequently, cytotoxic anti-Gal alpha(1,3)Gal antibodies in human serum play an important role in the lysis of fetal but not adult porcine islet cells.

Production of Fab fragments of monoclonal antibodies using polyelectrolyte complexes

A new method for the production of monovalent Fab fragments of antibodies has been developed. Traditionally Fab fragments are produced by proteolytic digestion of antibodies in solution followed by isolation of Fab fragments. In the case of monoclonal antibodies against inactivated subunits of glyceraldehyde-3-phosphate dehydrogenase, digestion with papain resulted in significant damage of the binding sites of the Fab fragments. Antigen was covalently attached to the polycation, poly(N-ethyl-4-vinylpyridinium bromide). Proteolysis of monoclonal antibodies in the presence of the antigen-polycation conjugate followed by (i) precipitation induced by addition of polyanion, poly(methacrylic) acid, and pH shift from 7.3 to 6.5 and (ii) elution at pH 3.0 resulted in 90% immunologically competent Fab fragments. Moreover, the papain concentration required for proteolysis was 10 times less in the case of antibodies bound to the antigen-polycation conjugate than that of free antibodies in solution. The digestion of antibodies bound to the antigen-polyelectrolyte complex was less damaging, suggesting that binding to the antigen-polycation conjugate not only protected binding sites of monoclonal antibodies from proteolytic damage but also facilitated the proteolysis probably by exposing antibody molecules in a way convenient for proteolytic attack by papain.