Structural characterization of the galactoxylomannan of Cryptococcus neoformans Cap67

The galactoxylomannan (GalXM) obtained from the culture supernatant of an acapsular mutant of Cryptococcus neoformans Cap67 was purified by Concanavalin A affinity, ion-exchange, and gel-filtration chromatographies. The structure of GalXM was determined by methylation analysis and by 1D and 2D NMR spectroscopic studies of the intact polysaccharide and of the oligosaccharide fragments generated by Smith degradation and by acetolysis. GalXM is a complex polysaccharide with an alpha-(1-->6) -galactan backbone. The polysaccharide is branched at c-3 of alternate Gal units of the backbone. C-3 is the point of attachment of the oligosaccharide side chains comprised of alpha-D-Man- (1-->3)-alpha-D-Man-(1-->4)- beta-D-Gal-substituted with zero to three terminal beta-Xyl residues as shown in the following structure: [formula: see text].     

Enzymatic synthesis of the alpha 3-galactosyl-Lex tetrasaccharide: a potential ligand for selectin-type adhesion molecules

Using recombinant UDP-Gal:Gal beta 1-->4GlcNAc alpha 1,3-galactosyltransferase and human milk alpha 1,3-fucosyltransferase the disaccharide Gal beta 1-->4GlcNAc has been converted in vitro into a tetrasaccharide product. The product has been characterized by gel filtration chromatography and HPLC and was analyzed using 1H-NMR. Based on NMR spectral data along with the known linkage specificity of the alpha 1,3-galactosyltransferase and the alpha 1,3-fucosyltransferase used, the chromatographic behaviour of the product, and the 1:1 molar ratios of the galactose and fucose residues calculated from incorporated radioactivity, it is concluded that the structure of the tetrasaccharide product is Gal alpha 1-->3Gal beta 1--4[Fuc alpha 1-->3]-GlcNAc. The tetrasaccharide is a non-charged analogue of the sialyl-Lex determinant that potentially may act as a ligand structure in selectin-mediated cell-cell adhesion.     

Intestinal immune system modulating polysaccharides from rhizomes of Atractylodes lancea

Hot water extract (ALR-0) of rhizomes of Atractylodes lanceo DC. was fractionated into MeOH-soluble fraction (ALR-1), supernatant fraction of EtOH precipitation (ALR-3 + 4), and crude polysaccharide fraction (ALR-5). Among these fractions, only ALR-5 showed potent stimulating activity for proliferation of bone marrow cells mediated by Peyer's patch cells. ALR-5 gave three potently active carbohydrate-rich fractions (ALR-5IIa, 5IIb, and 5IIc) by anion-exchange chromatography on DEAE-Sepharose CL-6B, and three active polysaccharides (ALR-5IIa-1-1, ALR-5IIb-2-2, and ALR-5IIc-3-1) were further purified from the respective fractions. The order of activity was revealed to be ALR-5IIb-2-2 > or = ALR-5IIa-1-1 > ALR-5IIc-3-1, ALR-5IIa-1-1, 5IIb-2-2, and 5IIc-3-1 each was eluted as a single peak on HPLC and their molecular weights were estimated to be 74,000, 3,100, 16,000, respectively. ALR-5IIa-1-1 consisted mainly of Ara and Gal (molar ratio; 0.6: 1.0) in addition to a trace amount of uronic acid whereas ALR-5IIb-2-2 and ALR-5IIc-3-1 mainly comprised Ara, Gal, GlcA, and GalA (molar ratio; 0.2: 1.0: 0.2: 0.8, and 0.5: 1.0: 0.7: 1.5, respectively). Methylation analysis indicated that ALR-5IIa-1-1 consisted mainly of terminal Araf, 4- or 5-linked Ara, 3.4- or 3.5-branched Ara, and 3-linked, 4-linked, and 3,6-branched Gal. ALR-5IIb-2-2 and ALR-5IIc-3-1 were composed mainly of terminal Araf, 4- or 5-linked Ara, 4-linked Gal, 4-linked GalA, and terminal GlcA. In addition, ALR-5IIb-2-2 mainly comprised 4-linked Xyl whereas ALR-5IIc-3-1 consisted mainly of 2,4-branched Rha. Single radial gel diffusion indicated that ALR-5IIa-1-1 showed a strong reactivity with beta-glucosyl-Yariv antigen, whereas ALR-5IIb-2-2 and ALR-5IIc-3-1 did not show the reactivity with the antigen. Treatments of ALR-5IIa with NalO4, NaClO2 and pronase did not reduce the stimulating activity for Peyer's patch cells, however combination of exo-alpha-L-arabinofuranosidase and exo-beta-D-(1-->3)-galactanase digestions of ALR-5IIa-1-1 significantly decreased its activity.     

Structural determination of the O-antigenic polysaccharide from the enterotoxigenic Escherichia coli O147

The structure of the O-antigenic polysaccharide from enterotoxigenic Escherichia coli O147 has been determined by NMR spectroscopy, and component and methylation analyses. The sequence of the sugar residues could be determined by NOESY and heteronuclear-multiple-bond-connectivity NMR experiments. It is concluded that the polysaccharide is composed of tetrasaccharide repeating units with the following structure: -->4)-beta-D-GalpA-(1-->3)-beta-D-GalpNAc-(1-->2)-alpha-L-Rhap+ ++-(1-->2)-alpha-L-Rhap-(1-->, where Rha represents 6-deoxymannose. The O-antigen of E. coli O147 is identical to the repeating unit of Shigella flexneri serotype 6 lipopolysaccharide, except that the latter contains an O-acetyl group at C3 of the rhamnosyl residue substituted by the N-acetylgalactosamine residue. Immunochemical analyses using a monoclonal antibody specific for the S. flexneri serotype 6 O-antigen showed an identical reactivity with both lipopolysaccharides.     

Purification and substrate specificities of two alpha-L-arabinofuranosidases from Aspergillus awamori IFO 4033

alpha-L-Arabinofuranosidases I and II were purified from the culture filtrate of Aspergillus awamori IFO 4033 and had molecular weights of 81,000 and 62,000 and pIs of 3.3 and 3.6, respectively. Both enzymes had an optimum pH of 4.0 and an optimum temperature of 60 degreesC and exhibited stability at pH values from 3 to 7 and at temperatures up to 60 degrees C. The enzymes released arabinose from p-nitrophenyl-alpha-L-arabinofuranoside, O-alpha-L-arabinofuranosyl-(1-->3)-O-beta-D-xylopyranosyl-(1-->4)-D-x ylopyranose, and arabinose-containing polysaccharides but not from O-beta-D-xylopyranosyl-(1-->2)-O-alpha-L-arabinofuranosyl-(1-->3)-O-b eta-D-xylopyranosyl-(1-->4)-O-beta-D-xylopyranosyl-(1-->4)-D-xylopyra nose. alpha-L-Arabinofuranosidase I also released arabinose from O-beta-D-xylopy-ranosyl-(1-->4)-[O-alpha-L-arabinofuranosyl- (1-->3)]- O-beta-D-xylopyranosyl-(1-->4)-D-xylopyranose. However, alpha-L-arabinofuranosidase II did not readily catalyze this hydrolysis reaction. alpha-L-Arabinofuranosidase I hydrolyzed all linkages that can occur between two alpha-L-arabinofuranosyl residues in the following order: (1-->5) linkage > (1-->3) linkage > (1-->2) linkage. alpha-L-Arabinofuranosidase II hydrolyzed the linkages in the following order: (1-->5) linkage > (1-->2) linkage > (1-->3) linkage. alpha-L-Arabinofuranosidase I preferentially hydrolyzed the (1-->5) linkage of branched arabinotrisaccharide. On the other hand, alpha-L-arabinofuranosidase II preferentially hydrolyzed the (1-->3) linkage in the same substrate. alpha-L-Arabinofuranosidase I released arabinose from the nonreducing terminus of arabinan, whereas alpha-L-arabinofuranosidase II preferentially hydrolyzed the arabinosyl side chain linkage of arabinan.     

Structure of an acidic exopolysaccharide of Burkholderia pseudomallei

A recently described water-soluble exopolysaccharide of Burkholderia pseudomallei recognized by the IgG 1 monoclonal antibody 3015 [Steinmetz, I., Rohde, M. & Brenneke, B. (1995) Infect. Immun. 63, 3959-3965] was isolated by repetitive ethanol-precipitation steps and by anion-exchange chromatography. The structure of the polysaccharide was determined by a combination of chemical-derivatization and mass-spectrometric techniques (compositional and methylation analysis, GC/MS, and electrospray-ionization-MS/MS of reduced and permethylated hydrolytic fragments), and two-dimensional 1H-NMR methods (COSY, TOCSY and NOESY) and confirmed by isolation and structural characterization of the depolymerized repeating unit of the polysaccharide. The combined structural data established a linear tetrasaccharide repeating unit consisting of three galactose residues, one bearing a 2-linked O-acetyl group, and a 3-deoxy-D-manno-2-octulosonic acid residue. [-->3)-beta-D-Galp2Ac-(1-->4)-alpha-D-Galp-(1-->3)-beta-D-Galp-(1- ->5)-beta-Kdo-(2-->]n     

Determination of the sialylation level and of the ratio alpha-(2-->3)/alpha-(2-->6) sialyl linkages of N-glycans by methylation and GC/MS analysis

A methodology for the determination of the sialylation pattern of N-glycans, extent of sialylation and the ratio between alpha-(2-->3) and alpha-(2-->6) sialyl linkages, is presented based on the labelling of the C-3 and C-6 hydroxyl groups of Gal residues obtained after permethylation, saponification, selective desialylation of sialylated oligosaccharides and methanolysis. Deuteromethylation and GC/MS analysis of Gal derivatives allow to determine the sialylation level of glycans. O-Ethyl ether labelling followed by GC analysis of the resulting Gal derivatives allows to obtain the ratio between alpha-(2-->3) and alpha-(2-->6) sialyl linkages. The method was applied to LNT (LcOse4: beta-D-Galp-(1-->3)-beta-D-GlcpNAc-(1-->3)-beta-D- Galp-(1-->4)-D-Glcp), LSTa (IV3NeuAcLcOse4: alpha-Neup5Ac-(2-->3)-beta-D-Galp-(1-->3)-beta-D- GlcpNac-(1-->3-beta-D-Galp-(1-->4)-D-Glcp), LSTc (IV6NeuAcn LcOse4: alpha-Neup5Ac-(2-->6)-beta-D-Galp-(1-->4)-beta-D-GlcpNAc-(1-->3)- beta-D-Galp-(1-->4)-D-Glcp) and a bisialylated biantennary N-glycan in which sialic acid is bound to Gal residues via an alpha-(2-->6) linkage. Using this method, it was found that 92.8% of N-glycans in bovine fetuin is sialylated and that the ratio of alpha-(2-->6) versus alpha-(2-->3) sialyl linkages was 31:19.     

Structural investigation of two cell-wall polysaccharides of Penicillium expansum strains

The structure of two cell-wall polysaccharides isolated from three different strains of Penicillium expansum, the type species of the genus, have been established by 1D and 2D NMR spectroscopy, and also by methylation analyses. The water-soluble polysaccharide F1S-B consisted of a linear tetrasaccharide repeating unit with the following structure: [-->6)-beta-D-Galf-(1-->5)-beta-D-Galf-(1-->5)-beta-D-Gal f-(1-->5)-beta-D- Galf-(1-->]n The alkali-soluble polysaccharide F1I is a (1-->3)-alpha-D-glucan.     

The O-specific polysaccharide chain of Campylobacter fetus serotype A lipopolysaccharide is a partially O-acetylated 1,3-linked alpha-D-mannan

A polysaccharide fraction liberated from Campylobacter fetus subsp. fetus serotype A lipopolysaccharide by mild acid hydrolysis followed by gel-permeation chromatography contained a partially O-acetylated D-mannan chain, as an O-specific polysaccharide, with a core oligosaccharide attached. The structure of the polysaccharide was studied by O-deacetylation, methylation, and 1H- and 13C-NMR spectroscopy, including computer-assisted analysis of the 13C-NMR spectrum. A structure of -->3)-alpha-D-Manp2Ac-(1--> was established as the structure of the O-specific polysaccharide, the degree of O-acetylation of the mannose residues at position 2 being estimated as 80-90%. As judged by the ratio of mannose to core constituents, the D-mannan chain consists on average of 10-12 monosaccharide units.     

Structure of the repeating unit of acid polysaccharide from Alteromonas sp. 4MS17

An acidic polysaccharide from Alteromonas sp. 4MC17 is built up of trisaccharide repeating units containing D-glucose, D-mannose and D-galacturonic acid residues. On the basis of methylation studies, 1H and 13C NMR-spectroscopy data, including two-dimensional homonuclear correlation spectroscopy and nuclear Overhauser effects, the following structure was suggested for the polysaccharide repeating unit: -->4)-beta-D-Glcp-(1-->4)-beta-D-GalpA-(1-->4)-beta-D-Manp-( 1-->.     

Asparagine-linked carbohydrate chains of inducible rat parotid proline-rich glycoprotein contain terminal beta-linked N-acetylgalactosamine

Rats treated with daily injection of DL-isoproterenol for 10 consecutive days (25 mg kg(-1) body weight) showed marked induction of a proline-rich glycoprotein (GPRP) of 220 kDa. Proteinase K digestion of GPRP produced a homogeneous glycopeptide with an average chemical composition as follows (residues per mol): Pro4, Glx3, Asx2, Gly1, His1, Thr1, Arg1, GlcNAc5, GalNac1, Man3, Gal2-3, and Fuc1. The structural analysis of the asparagine-linked carbohydrate unit was performed by methylation, periodate oxidation and enzymatic degradation. Methylation studies indicated that the three mannosyl residues were substituted at 1,2-, 1,2,4-, and 1,3,6-positions. Fucose, N-acetylgalactosamine, 1.5 residues of galactose and 0.35 residues of N-acetylglucosamine were terminally located and one galactose residue was 1,4-substituted. Approximately four of the 5 N-acetylglucosamine residues were substituted at 1,4-position and approximately 1 residue of N-acetylglucosamine was substituted at 1,4,6-positions. Periodate oxidation studies and exoglycosidase results were consistent with the methylation data. Based on the results of Smith degradation, methylation and sequential exoglycosidase digestions a triantennary oligosaccharide structure having terminal N-acetylgalactosamine in one of the branches is proposed for the major Asn-linked carbohydrate moiety of GPRP.     

Isolation and purification of feruloylated oligosaccharides from cell walls of sugar-beet pulp

Cell walls from sugar-beet pulp contain some feruloyl groups linked to the pectic neutral side-chains. Enzymic as well as chemical hydrolysis of the pulp yielded a series of feruloylated oligosaccharides, which have been purified by Sephadex LH-20 and Biogel P-2 chromatography in aqueous solvents. Feruloylated arabinose di-, tri-, hexa-, hepta-, and octa-saccharides as well as feruloylated galactose disaccharides were obtained after hydrolysis of the pulp with a mixture of fungal carbohydrases (Driselase). Feruloylated arabinose and galactose monosaccharides were obtained through mild acid hydrolyses. Both arabinose and galactose residues in the side-chains are feruloylated, 50-55% of the feruloyl groups being linked to arabinose residues and 45-50% to galactose residues. It is concluded that 1 out of 56 arabinose residues and 1 out of 16 galactose residues present as pectic side-chains in sugar-beet pulp carry a feruloyl group.     

Substrate specificities of alpha-L-arabinofuranosidases produced by two species of Aspergillus niger

Precise substrate specificities of alpha-L-arabinofuranosidases from Aspergillus niger 5-16 and Aspergillus niger (Megazyme) were investigated. Both enzymes hydrolyzed arabinan and debranched-arabinan at almost the same rate. The alpha-L-Arabinofuranosidase from A. niger (Megazyme) preferentially released arabinosyl side-chains of arabinan. The enzyme tore off both arabinoses attached to O-alpha-L-arabinofuranosyl-(1-->3)-O-beta-D-xylopyranosyl-(1--> 4)-D-xylopyranose and O-beta-D-xylopyranosyl-(1-->4)-[O-alpha-L- arabinofuranosyl-(1-->3)]-O-beta-D-xylopyranosyl-(1-->4)-D-xylopyranose, but did not tear off xylosyl-arabinose from O-beta-D-xylopyranosyl-(1-->2)-O-alpha-L-arabinofuranosyl-(1-->3) -O-beta-D-xylopyranosyl-(1-->4)-O-beta-D-xylopyranosyl-(1-->4)-D- xylopyranose. The enzyme from A. niger (Megazyme) hydrolyzed methyl 2-O-, methyl 3-O- and methyl 5-O-alpha-L-arabinofuranosyl-alpha-L-arabinofuranosides to arabinose and methyl alpha-L-arabinofuranoside in the order of (1-->5)->(1-->2)->(1-->3)-linkages. On the other hand, alpha-L-arabinofuranosidase from A. niger 5-16 successively liberated the arabinose of arabinan from non-reducing terminals. The enzyme hydrolyzed in the order of (1-->2- > (1-->3)- > (1-->5)-linkages. Both of the enzymes hydrolyzed the (1-->3)-linkage more than the (1-->5)-linkage of methyl 3,5-di-O-alpha-L-arabinofuranosyl-alpha-L-arabinofuranoside.     

Automatic and effortful processes in auditory memory reflected by event-related potentials. Age-related findings

The structures of the N-linked sugar chains in the PAS-6 glycoprotein (PAS-6) from the bovine milk fat globule membrane were determined. The sugar chains were liberated from PAS-6 by hydrazinolysis, and the pyridylaminated sugar chains were separated into a neutral (6N) and two acidic chains (6M and 6D), the acidic sugar chains then being converted to neutral sugar chains (6MN and 6DN). 6N was separated into two neutral fractions (6N13 and 6N5.5), while 6MN and 6DN each gave a single fraction (6MN13 and 6DN13). The structure of 6N5.5, which was the major sugar chain in PAS-6, is proposed to be Man alpha1 --> 6 (Man alpha1 --> 3) Man beta1 --> 4GlcNAc beta1 --> 4GlcNAc-PA; 6N13, 6MN13 and 6DN13 are proposed to be Gal beta1 --> 3Gal beta1 --> 4GlcNAc beta1 --> 2Man alpha1 --> 6 (Gal beta1 --> 3Gal beta1 --> 4GlcNAc beta1 --> 2Man alpha1 --> 3) Man beta1 --> 4GlcNAc beta1 --> 4 (Fuc alpha1 --> 6)GlcNAc-PA; 6M and 6D had 1 or 2 additional NeuAc residues at the non-reducing ends of 6MN13 and 6DN13, respectively.     

Neuroleptic malignant syndrome associated with multiple joint dislocations in a trauma patient

The structure of the O-antigenic polysaccharide from Escherichia coli O141 has been determined. NMR spectroscopy and sugar and methylation analyses were the principal methods used. The sequence of the sugar residues could be determined by NOESY and heteronuclear multiple-bond connectivity (HMBC-) NMR experiments. The polysaccharide is composed of pentasaccharide repeating units with 1 O-acetyl group/repeating unit. The following structure, where Rha is 6-deoxymannose is concluded: carbohydrate sequence [see text].     

Two novel probes reveal tubular and vascular Arg-Gly-Asp (RGD) binding sites in the ischemic rat kidney

The structure of a sulfated polysaccharide isolated from the calcareous red alga Corallina pilulifera was studied by methylation analysis before and after desulfation or Smith degradation, as well as by 1D and 2D 1H and 13C NMR spectroscopy. The polysaccharide was shown to consist of D-galactose, L-galactose, 2-O-methyl-L-galactose, 3-O-methyl-L-galactose, 6-O-methyl-D-galactose, D-xylose, and sulfate in a molar ratio of 29:20:5:2:1:20:23. Its agaran-like backbone built up of alternating 3-linked beta-D-galactopyranose and 4-linked alpha-L-galactopyranose residues bears single beta-D-xylopyranosyl substituents at position 6 of beta-D-galactose residues, whereas sulfate and O-methyl groups occupy positions 2 and 3 of alpha-L-galactose and position 6 of beta-D-galactose residues.     

NMR spectroscopic elucidation of the structure of a glycerol teichoic acid-like O-specific polysaccharide of the bacterium Hafnia alvei strain PCM 1199

The structure of the acidic O-specific polysaccharide of a Gram-negative bacterium, H. alvei strain PCM 1199, was studied by NMR spectroscopy including two-dimensional correlation spectroscopy (COSY), total correlation spectroscopy (TOCSY), nuclear Overhauser effect spectroscopy (NOESY), 1H, 13C heteronuclear single-quantum coherence (HSQC), 1H, 13C heteronuclear multiple-bond correlation (HMBC), and one-dimensional 1H, 31P heteronuclear multiple-quantum coherence (HMQC) experiments. It was found that the polysaccharide contains D-galactose, 2-acetamido-2-deoxy-D-glucose, 4-acetamido-4,6-dideoxy-D-glucose, glycerol, and phosphate in the ratios 1:2:1:1:1, as well as O-acetyl groups in non-stoichiometric amounts. The polysaccharide is similar in structure to teichoic acids of Gram-positive bacteria and has the following structure of the repeating unit: 3)-beta-D-Galp-(1-->3)-alpha-D-GlcpNAc-(1-->3)-beta-D-Quip4NAc-(1- ->1)-Gro- 3-P-(O--> [formula: see text] beta-D-GlcpNAc [formula: see text] The O-specific polysaccharide of H. alvei PCM 1199 is structurally related to another teichoic acid-like O-specific polysaccharide of H. alvei PCM 1205 studied by us earlier.     

Expression and characterization of a lactosaminoglycan-carrying glycoprotein of Zajdela hepatoma cell surface--structural analysis of the carbohydrate moiety

In poorly differentiated hepatoma cells, a glycoprotein carrying lactosaminoglycans is identified, and the structure of its glycan moiety is proposed. After membrane solubilization, protein fractionation by gel filtration, and electroelution, this glycoprotein (GPIII) was identified by its affinity for Datura stramonium lectin and its content in large glycopeptides. As shown by PAGE, GPIII has an apparent molecular mass of 100 kDa and is highly glycosylated (36%). It appears as an integral membrane glycoprotein. It is absent from normal hepatocytes, in that no heavy glycopeptides could be detected that bound to Datura lectin or to specific antiserum. The glycan moiety of GPIII has been analyzed according to carbohydrate composition, glycosidase treatment, affinity chromatography on immobilized pokeweed, Datura and Griffonia lectins, and by NMR and methylation analyses. The glycan is a N-linked tetraantennary lactosaminoglycan of 6.6 kDa, containing Gal, GlcNAc, Man, and NeuNAc in a 16:14:3:4 molar ratio, with an average of three repeating units/branch. Its beta-Gal residues are in the penultimate position and are linked in beta1-4 at least in four structural elements (three peripheral and one internal). It contains a very branched structure with Gal alpha1-3Gal beta1-4GlcNAc side chains linked in the C6 position to an inner Gal residue in a main branch. Alpha-Gal and NeuNAc residues [mainly NeuNAc alpha(2-3) linkage] are expressed as the nonreducing terminal groups. A possible structural model is proposed for this heterogeneous lactosaminoglycan, although no definitive structure can be established. That this lactosaminoglycan-carrying glycoprotein GPIII is not expressed in hepatocytes suggests its expression to be linked to the undifferentiated and/or malignant state of this hepatoma.     

Gastroparesis after celiac plexus block

Pectin constituents, which were about 70 w/w% of extracellular polysaccharides (ECP) from a cell-suspension culture of Mentha, were purified by gel filtration chromatography, and their sugar composition and linkage were investigated. Two major constituents identified were (1-->3)-linked galactan carrying arabinosyl residues on C-6 and (1-->4)-alpha-linked galacturonan partially interspersed with (1-->2)-linked rhamnosyl resides. Acetylated or methylated pectins were not identified on 1H-NMR analysis.     

Human preformed IgG combining with membrane-bound porcine serotransferrin lyse porcine endothelial cells through antibody-dependent cellular cytotoxicity

Preformed antibodies are involved in xenograft rejection. The purpose of this work was to characterize porcine xenoantigens recognized by human preformed IgG (hpIgG), and to investigate the role of hpIgG in xenogeneic rejection. IgG eluted from porcine livers perfused with human plasma, human sera and total human IgG were immunoblotted on porcine aortic endothelial cell extracts. The amino acid sequence of a 76-kDa antigen constantly revealed was 100% homologous with porcine serotransferrin (psTf). hpIgG from human sera, human IgG1 and IgG2 and F(ab')2gamma specifically bound to psTf. Neutralization by psTf abolished that binding. Although alpha1,3-linked galactose residues (Gal(alpha)1,3Gal) is the dominant epitope recognized by preformed antibodies in the swine-to-human combination, the analysis of carbohydrate composition of psTf showed that the molecule was devoid of Gal(alpha)1,3Gal moieties and that preformed anti-psTf IgG bound to epitopes localized on the peptide core of the molecule. Purified human anti-psTf IgG antibodies were able to bind to psTf linked to its receptor on porcine endothelial cells, and to kill those cells through antibody-dependent cellular cytotoxicity.