Aminopropyl silica gel as a solid support for preparation of glycolipid immunoadsorbent and purification of antibodies

Structural changes of silica mesocellular foam supported amine-functionalized CO2 adsorbents upon exposure to steam

Three classes of amine-functionalized mesocellular foam (MCF) materials are prepared and evaluated as CO(2) adsorbents. The stability of the adsorbents under steam/air and steam/nitrogen conditions is investigated using a Parr autoclave reactor to simulate, in an accelerated manner, the exposure that such adsorbents will see under steam stripping regeneration conditions at various temperatures. The CO(2) capacity and organic content of all adsorbents decrease after steam treatment under both steam/air and steam/nitrogen conditions, primarily due to structural collapse of the MCF framework, but with additional contributions likely associated with amine degradation during treatment under harsh conditions. Treatment with steam/air is found to have stronger effect on the CO(2) capacity of the adsorbents compared to steam/nitrogen.

A convenient oxidation of natural glycosphingolipids to their "ceramide acids" for neoglycoconjugation. Bovine serum albumin-glycosylceramide acid conjugates as investigative probes for HIV gp120 coat protein-glycosphingolipid interactions

A new method to cleave the double bond of sphingolipids has been developed. Using limited concentrations of KMnO4 and an excess of NaIO4, in a neutral aqueous tert-butanol solvent system gave nearly quantitative yields of the oxidized product. A variety of natural glycosphingolipids (GSLs): GlcC, GalC, SGC, LC, Gb3C, Gb4C, Gg4C, Gb5C, and GM1C, gave the corresponding acids: 2-hydroxy-3-(N-acyl)-4-(O-glycosyl)-oxybutyric acids, i.e. "glycosyl ceramide acids" (GSL.CCOOH) in excellent yields (80-90%). Deacyl GSLs (dGSLs) were oxidized to acids containing the oligosaccharides devoid of hydrocarbon chains, i.e. "ceramide oligosaccharides" (dGSL. NRR1CCOOH, where R = R1 = H; R = H, R1 = CH3CO; or R = R1 = Me). The efficacy of this method was demonstrated by transforming natural GSLs: GlcC, GalC, GalS, SGC, LC, Gb3C, and Gb4C into neoglycoproteins via coupling glycosyl ceramide acids (except GalS, which was coupled directly) to bovine serum albumin (BSA). Mass spectroscopic analysis of GalC-BSA conjugates, (GalC.CONH)nBSA and (GalS.NHCO)nBSA gave a value of 9 +/- 1 and 16 +/- 2 for n. Neoglycoconjugates derived from GlcC, GalC (type I and II and the behenic analog), SGC, LC, and Gb3C were recognized by the recombinant human immunodeficiency virus coat protein gp120 (rgp120). The GalS conjugate showed significantly reduced binding, and the Gb4C conjugate showed no binding. Thus, rgp120/GSL-BSA interaction requires a terminal galactose and/or glucose residue. Terminal N-acetylgalactosamine containing GSLs are not bound. The ceramide acid conjugates provide a more effective scaffold for presentation of glycone for rgp120 binding than those derived from dGSLs. The retention of receptor specificity of the glycoconjugates was validated by retention of the expected binding specificity of VT1 and VT2e for Gb3C and Gb4C conjugates, respectively. These studies open a new vista in the generation of glycoconjugates from GSLs and further emphasize the role of aglycone in glycolipid recognition.

Affinity purification of antibodies from sera using polyvinylidenedifluoride (PVDF) membranes as coupling matrices for antigens presented by autoantibodies to triosephosphate isomerase

Polyvinylidenedifluoride (PVDF) membranes covered with antigen can be used for affinity purification of antibodies from sera. These antibodies serve as an appropriate substitute for monoclonal antibodies when performing cytological and analytical experiments with the respective antigen. The usefulness of this method is demonstrated with the purification of IgM autoantibodies produced against human triosephosphate isomerase in acute Epstein-Barr virus infection. Compared with the original serum, the specific activity of the purified antibodies was up to 1400-fold higher, and the recovery of the anti-triosephosphate isomerase activity between 25 and 33%.

Gangliosides noncovalently bound to DEAE-Sephadex: application to purification of anti-ganglioside antibodies

A simple, rapid, effective, and inexpensive method for the purification of ligands having high affinity for gangliosides has been developed. DEAE-Sephadex has a high capacity for binding gangliosides (approx 1/1.6, w/w). The gangliosides, bound to the support by electrostatic and hydrophobic interactions, showed a high resistance, in an aqueous environment, to being detached by eluants commonly employed to desorb ligands (i.e., low or high pH or chaotropic agent solutions) or by nonionic detergent solutions as well as by organic solvents. The DEAE-Sephadex-ganglioside complex was assayed as an immunoadsorbent for purifying anti-GM1 ganglioside antibodies from serum of an immunized rabbit. The specific activity of the purified antibodies was 200- to 400-fold higher, and the recovery of the anti-ganglioside activity was above 50%, with respect to the untreated antiserum. The preparation of the complex and the purification of the antibodies can be done in less than 5 h. The glycolipids from the complex can be recovered by elution with organic solvents containing salt or volatile base solutions, and reused. In principle, this method can be adapted for other anionic amphipathic receptor molecules to purify ligands which bind to them.

Glycosphingolipids of human plasma

A number of glycosphingolipids, including 10 gangliosides, not previously identified in human plasma have been characterized. The plasma contains 2 micrograms of lipid-bound sialic acid/ml plasma and 54% of the gangliosides are monosialo, 30% disialo, 10% trisialo, and 6% tetrasialo. Individual glycosphingolipids were purified by high-performance liquid chromatography and thin-layer chromatography, and were characterized on the basis of their chromatographic mobility, carbohydrate composition, hydrolysis by glycosidases, methylation analysis, and immunostaining with anti-glycosphingolipid antibodies. The monosialogangliosides were identified as GM3, GM2, sialosyl(2-3)- and sialosyl(2-6)lactoneotetraosylceramides, sialosyllacto-N-nor-hexaosylceramide, and sialosyllacto-N-isooctaosylceramide. The major gangliosides in the polysialo fractions contained a ganglio-N-tetraose backbone and were identified as GD3, GD1a, GD1b, and GQ1b. The most abundant neutral glycosphingolipids were glucosyl, lactosyl, globotriaosyl, globotetraosyl and lactoneotetraosylceramides. The other neutral glycosphingolipids, tentatively identified by immunostaining with monoclonal antibodies, contained H1, Lea, Leb, and lacto-N-fucopentose III (X hapten) structures.

Sialosylglobotetraosylceramide: a marker for amyotropic lateral sclerosis

Gangliosides of healthy and pathologic muscles (amyotropic lateral sclerosis and facio-scapulo-humeral muscular dystrophy) were studied. Total ganglioside content of the affected muscles was approximately 2 fold higher than the unaffected muscles. Our results showed that ALS muscle contained a ganglioside which was absent in the unaffected and FSH muscular dystrophic muscles. Based on the results of hydrolysis with Vibrio cholerae neuraminidase and subsequent reactivity of the asialo derivative towards anti-globotetraosylceramide, we propose that the ALS ganglioside is sialosylglobtetraosylceramide, NeuAc(alpha 2-3)Ga1NAc(beta 1-3)Ga1(alpha 1-4)Ga1(beta 1-4)G1c-Cer.

Genetic regulation of GM2 (NeuGc) expression in liver of mouse

GM2 containing NeuGc was a major ganglioside in mouse liver of inbred strains such as DBA/2, BALB/c, C57BL/10 and C3H/He, which are commonly used for biochemical and immunological studies. On the other hand, the liver of WHT/Ht, an inbred strain, contained GM3 (NeuGc) as a major ganglioside and lacked GM2 (NeuGc). We report here that the GM2 (NeuGc) expression was analyzed in the liver of the progeny between WHT/Ht and DBA/2 and the positive expression of GM2 (NeuGc) was proved to be a dominant trait regulated by an autosomal single gene. Moreover, the N-acetylgalactosaminyltransferase activity to convert GM3 (NeuGc) to GM2 (NeuGc) was measured in the liver microsomal fraction of WHT/Ht, BALB/c and their F1. F1 expressed almost half of the activity in BALB/c and WHT/Ht did not express a detectable amount of activity. The backcross of F1 to WHT/Ht segregated into two groups. One expressed both GM2 (NeuGc) and the transferase activity and the other expressed neither of them. There was no exceptional individual which was not grouped into either of these two groups. These results indicate that GM2 (NeuGc) expression is directly regulated by the N -acetylgalactosaminyltregated into two groups. One expressed both GM2 (NeuGc) and the transferase activity and the other expressed neither of them. There was no exceptional individual which was not grouped into either of these two groups. These results indicate that GM2 (NeuGc) expression is directly regulated by the N-acetylgalactosaminyltransferase activity, the expression of the enzyme activity is regulated by an autosomal single gene and WHT/Ht is a mutant of the recessive homozygote which cannot express the enzyme activity in its liver. WHT/Ht does not develop any neurological symptoms but grows and breeds well. The brain ganglioside composition was proved to be identical to those in BALB/c brain. The result suggests that WHT/Ht has N-acetylgalactosaminyltransferase to convert GM3 (NeuAc) to GM2 (NeuAc) in its brain. It is a subject for further study to elucidate what kind of defect is involved in the GM2 (NeuGc) biosynthesis of WHT/Ht liver.

Rapid separation of gangliosides by high-performance liquid chromatography

We have developed a high-performance liquid chromatographic (HPLC) procedure for the rapid separation of individual ganglioside components on a 5-micron porous silica gel column using a mixture of isopropanol-hexane-water with increasing water content and decreasing hexane content. Total ganglioside mixtures were first fractionated on DEAE-silica gel according to the number of sialic acid residues. Each fraction was then separated into individual ganglioside components by HPLC. Total elution time was less than 2 h. This procedure has been applied for the separation of major ganglioside components of human erythrocytes and beef brain and is highly reproducible.

Demyelination in vitro. Absorption studies demonstrate that galactocerebroside is a major target

Myelinated cultures of mouse spinal cord have been exposed to sera raised in rabbits against whole white matter (anti-WM), myelin basic protein (anti-MBP) and galactocerebroside (anti-GC), the major glycolipid of CNS myelin, to determine which factor in central nervous system (CNS) tissue in vitro is the target of serum demyelinating and myelin swelling antibodies. The sera were tested by radioimmunoassay for activity against MBP and against GC and were also specifically absorbed with MBP, GC and control antigens. Studies were also performed with and without active complement. The findings show that demyelination and myelin swelling in vitro are caused by antibodies against GC and not against MBP. Ultrastructurally, the effects of anti-WM and anti-GC sera with and without complement were indistinguishable. This study demonstrates that GC is a major target in antibody-mediated demyelination.

An immunological model of epilepsy: seizures induced by antibodies to GM1 ganglioside

Following observations that the intracerebral injection into rats of antiserum to brain gangliosides resulted in recurrent epileptiform activity and that seizure activity was not seen if antibodies were removed by absorption of the antiserum with pure GM1 ganglioside, a study was undertaken to establish characteristics of the immunological agents used to produce this model of epilepsy. It was determined that the potencies (antibody titers with GM1 ganglioside) of antiganglioside sera can be correlated with the intensities of epileptiform activity they induce; that immunoglobulin fractions from antiganglioside sera are even more effective biologically than the antisera; and that antibodies to GM1 ganglioside purified by affinity chromatography can also induce recurrent epileptiform discharges but are not as effective as either native antiserum or immunoglobulin fractions.

Immunochemical relationship between Forssman and globoside glycolipid antigens

The rabbit antibody response to the human blood group P glycolipid antigen, globoside, GalNAc(beta 1-3)Gal(alpha 1-4)Gal(beta 1-4)Glc-Cer, has been examined with respect to cross-reactions with the structurally related Forssman glycolipid GalNAc(alpha 1-3)GalNAc(beta 1-3)Gal(alpha 1-4)Gal(beta 1-4)Glc-Cer. Immunoadsorbent columns were used to isolate three purified antibody populations from the anti-globoside sera: (1) fraction A, antibodies that cross-react with both glycolipids; (2) fraction B, antibodies that react with Forssman antigen but not with globoside; and (3) fraction C, antibodies that are specific for globoside. The proportion of each fraction in the total antibody response to globoside appears to be related to preexisting immunity to these antigens. A rabbit with a high preimmune titer to Forssman antigen produced a large amount of Forssman-specific antibody, whereas a rabbit with a low or nonexistent preimmune titer of anti-Forssman antibody produced large amounts of globoside-specific antibody. The presence of Forssman-specific antibody in an immune response to globoside is an example of a heteroclitic type of immune response.

A new Pk phenotype in the P blood group system

A healthy 22-year-old woman was noted to have erythrocytes of the Pk phenotype: a strong Pk antigen, no detectable P antigen and anti-P antibody in her serum. Her erythrocytes contained four to six times as much Pk glycolipid (globotriaosylceramide or CTH) and approximately half as much P glycolipid (globotetraosylceramide or globoside) as normal red cells. The structures of CTH and globoside were characterized by analysis of permethylated sugars and complement fixation, in addition to chromatographic mobility and sugar composition. Inasmuch as the erythrocytes of two Pk individuals that were analysed previously (Marcus et al., 1976) contained no detectable globoside, these abnormalities appear to represent a new phenotype in the P blood group system.

Preparation and properties of antibodies to GD3 and GM1 gangliosides

Gangliosides GD3 and GM1 were coupled to proteins by their carboxyl groups and antisera were raised against the complexes. Anti-ganglioside antibodies were isolated by affinity chromatography on ganglioside-aminopropyl silica gel columns, and the specificity of the antibodies was determined by a quantitative microcomplement fixation assay. Antibodies to GD3 were highly specific and did not crossreact with GM3, lactosyl ceramide, or other glycolipids. Purified antibodies to GM1, in contrast, crossreacted with asialo-GM1, GD1b, and, to a lesser extent, GM2 and asialo-GM2. A derivative of GM1, containing a C-7 sialic acid residue produced by periodate oxidation, reacted with the ani-GM1 antibodies almost as readily as with GM1. The specificities of anti-GM1 antibodies elicited by the covalent ganglioside-protein complexes were similar to those produced by immunization with noncovalent complexes of GM1 and methylated bovine serum albumin. The ganglioside-protein complexes described here should be useful for preparing antibodies to polysialogangliosides that contain neuraminidase-sensitive linkages.