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PubMed1971

Characterization of two cell-wall polysaccharides from Fusicoccum amygdali.

1. The nature of two polysaccharides (s(0) (20) values 6S and 2S respectively in 1m-sodium hydroxide), comprising a fragment (fraction BB, [alpha](D) +236 degrees in 1m-sodium hydroxide), previously isolated from cell walls of Fusicoccum amygdali, has been investigated. 2. Both the major (2S) and minor (6S) components were affected by incubation with alpha-amylase. The 6S polysaccharide was also attacked by exo-beta-(1-->3)-glucanase, which is evidence that it contained both alpha-(1-->4)- and beta-(1-->3)-glucopyranose linkages. By fractionation of the products of alpha-amylase-treated fraction BB it was possible to obtain a water-insoluble polysaccharide, fraction P ([alpha](D) +290 degrees in 1m-sodium hydroxide, 67% of fraction BB) and a water-soluble polysaccharide, fraction Q ([alpha](D) +16 degrees in 1m-sodium hydroxide, 11% of fraction BB), both of which sedimented as single boundaries with s(0) (20) values (in 1m-sodium hydroxide) of 1.7S and 4.6S respectively. 3. Evidence from periodate oxidation, methylation analysis, i.r. spectroscopy and partial acid hydrolysis showed that fraction P consisted of linear chains of alpha-(1-->3)-glucopyranose units with blocks of one or two alpha-(1-->4)-glucopyranose units interspersed at intervals along the main chain. The 2S polysaccharide, from which fraction P is derived, evidently also contains longer blocks of alpha-(1-->4)-glucopyranose units, that are susceptible to alpha-amylase action. 4. Fraction Q consisted of glucose (88%) with small amounts of galactose, mannose and rhamnose. Evidence from digestion with exo- and endo-beta-(1-->3)-glucanases, periodate oxidation and methylation analysis suggests that fraction Q consists of a branched galactomannorhamnan core, to which is attached a beta-(1-->3)-, beta-(1-->6)-glucan. In the cell wall, chains of alpha-(1-->4)-linked glucopyranose units are linked to fraction Q to form the 6S component of fraction BB.

Amylases↗
PubMed1977

Influence of cations at the plasma membrane in controlling polysaccharide secretion from sycamore suspension cells.

1. Three soluble polysaccharides and a soluble protein containing hydroxyproline were secreted by sycamore suspension cultures. l-[1-(3)H]Fucose was incorporated solely into the fucose of fucoxyloglucan and l-[1-(14)C]arabinose mainly into the arabinose of arabino-galactan. [U-(14)C]Glucose was a general precursor for soluble protein and polysaccharides. 2. The steady-state rate of secretion of all the polymers was increased within seconds of adding various electrolytes and polyelectrolytes to the growth medium. The increased secretion was induced by cations at the outer surface of the plasma membrane. It was brought about by a stimulation of the normal mechanisms of cell-wall polysaccharide secretion. It was partly inhibited by anaerobiosis or sodium arsenate and was unaffected by temperature changes in the range 0-35 degrees C. 3. The precursor pool from which secretion was induced contained completely synthesized polysaccharides and was probably located in the Golgi-derived vesicles. The results indicated that the endoplasmic reticulum did not secrete polysaccharide directly to the cell exterior. 4. The various cations probably induced secretion by causing a depolarization of the negative electric potential of the cell surface, and this resulted in the fusion of vesicles with the plasma membrane. 5. Analogy with exocytosis and pinocytosis in various animal tissues suggested that the decreased surface potential brought about membrane fusion by causing an increase in plasma-membrane permeability to Ca(2+). 6. The results showed that the fusion of vesicles with the plasma membrane was rate-limiting and a potential control point. Auxin-stimulated cell-wall deposition could be a result of a stimulated influx of Ca(2+) causing vesicle fusion with the plasma membrane.

Calcium Chloride↗
PubMed2000

Development of antibodies against tetravalent meningococcal polysaccharides in revaccinated complement-deficient patients.

Individuals deficient in C3 or a late complement component are susceptible to recurrent meningococcal infections. Since they experience meningococcal episodes mostly with uncommon meningococcal serogroups, vaccination with a tetravalent vaccine containing A, C, Y and W135 polysaccharides has been suggested. We vaccinated a cohort of two C3 and 17 late complement component-deficient (LCCD) patients, revaccinated them 7 years later and investigated the development of their IgG antibodies to the capsular polysaccharides of the meningococcal vaccine. Seven years after the first vaccination levels of IgG antibodies declined compared with the levels present at 6 months after the first vaccination, but were still at least four times higher than before vaccination. Levels of antibodies to Y polysaccharide in serum of complement-deficient patients were rather low but they did not differ significantly from those in serum of healthy non-related controls (P = 0.07). Three months after the second vaccination IgG antibodies against all polysaccharides increased, exceeding those measured at 6 months after the first vaccination. In the 8 years of observation after the first vaccination two new meningococcal infections with strains related to the vaccine (serogroup Y strains) occurred in two patients, 3.5 and 5 years after the first vaccination. Our findings show that high IgG antibody levels against the tetravalent meningococcal polysaccharide vaccine were reached after revaccination of two C3 and 17 LCCD individuals 7 years after the first vaccination. Whether revaccination should be required within a period shorter than 7 years is discussed, since two vaccinees developed meningococcal disease to vaccine serogroup Y.

Adolescent↗
PubMed1998

Synthesis of Escherichia coli O9a polysaccharide requires the participation of two domains of WbdA, a mannosyltransferase encoded within the wb* gene cluster.

WbdA (previously MtfA) is one of the mannosyltransferases encoded within the Escherichia coli O9a wb* gene cluster. It is composed of two domains of similar size, connected by an alpha-helix chain. Elimination of the C-terminal half by transposon insertion or gene deletion caused synthesis of an altered structural O-polysaccharide consisting only of alpha-1,2-linked mannose. O9a polysaccharide synthesis was restored by the C-terminal half of WbdA in trans. No membrane incorporation of mannose from GDP mannose was observed in a strain carrying only the gene for truncated WbdA. For mannose incorporation, it was necessary to introduce both wbdB and wbdC genes into the strain. Therefore, it is likely that the N-terminal half of truncated WbdA synthesizes the altered O-polysaccharide together with other mannosyltransferases which participate in the initial reactions of the O9a polysaccharide synthesis. Both N- and C-terminal domains of WbdA are required for the synthesis of the complete E. coli O9a polysaccharide. The chi sequence location between the two domains and homology plot analyses of the wbdA and the WbdA protein suggested that the wbdA gene might have arisen by fusion of two independent genes.

Conserved Sequence↗
PubMed2003

A unique variant of streptococcal group O-antigen (C-polysaccharide) that lacks phosphocholine.

Streptococcus mitis strain SK598, which represents a subgroup of biovar 1, possesses a unique variant of the C-polysaccharide found in the cell wall of all strains of Streptococcus pneumoniae and in some strains of S. mitis. This new variant lacks the choline methyl groups in contrast to the previously characterized forms of C-polysaccharide, which all contain one or two choline residues per repeat. The following structure of the repeating unit of the SK598 polysaccharide was established: where AAT is 2-acetamido-4-amino-2,4,6-trideoxy-d-galactose. This structure is identical to the double choline-substituted form of C-polysaccharide, except that it is substituted with ethanolamine instead of choline. This extends the number of recognized C-polysaccharide variants to four.

Carbohydrate Sequence↗
PubMed2004

In vitro anti-adhesive activity of an acidic polysaccharide from Panax ginseng on Porphyromonas gingivalis binding to erythrocytes.

A polysaccharide with high uronic acid content from the roots of Panax ginseng was found to inhibit the ability of Porphyromonas gingivalis to agglutinate erythrocytes. This polysaccharide showed a strong inhibitory activity (minimum inhibitory concentration 0.25 mg/mL), but treatment with pectinase resulted in non-inhibitory hydrolyzed products. In contrast, the inhibition by the acidic polysaccharide from the leaves of Artemisia capillaris was negligible. The carbohydrate composition of the two polysaccharides indicated that the anti-adhesive activity may be correlated with glucuronic acid content, one of the components of glycosaminoglycans. Low molecular weight heparin and sucrose octasulfate revealed stronger inhibitory effects on bacterial binding, than the acidic polysaccharide from P. ginseng.

Anticoagulants↗
PubMed1997

Fractionation and chemical properties of immunomodulating polysaccharides from roots of Dipsacus asperoides.

A crude polysaccharide fraction (DAP-1) was prepared from roots of Dipsacus asperoides by hot water extraction and EtOH precipitation, and tested for anti-complementary activity, mitogenic activity of lymphocytes, and effects on acid phosphatase and phagocytic activities of macrophages. DAP-1 showed not only anti-complementary activity but also a stimulating effect on the mitogenic activity of lymphocytes. DAP-1 also significantly suppressed the phagocytic activity of macrophages. Although DAP-1 directly stimulated the mitogenecity of lymphocytes, it had no effect on lipopolysaccharide- or concanavalin A-induced mitogenic activity of lymphocytes. Periodate oxidation and pronase digestion suggested that the polysaccharide moiety in DAP-1 contributed to the expression of its anti-complementary and mitogenic activities and that the protein moiety in DAP-1 was responsible for its effect on phagocytosis. DAP-1 gave three polysaccharide fractions (DAP-2, 3, and 4) by fractionation using cetyltrimethylammonium bromide. All the fractions had potent anti-complementary activity, but showed different stimulating or suppressive effects on the proliferation of lymphocytes, phagocytosis, or acid phosphatase activity. Three potent anti-complementary polysaccharides (DAP-4I-1a, DAP-4I-1b, and DAP-4IIa-1) were purified from DAP-4 by anion-exchange chromatography, gel filtration, and HPLC. DAP-4I-1a, I-1b, and IIa-1 consisted of Ara, Rha, Xyl, Gal, Glc and GlcA in a molar ratio of 1.0:0.7:1.0:18.6:22.2:nil; 1.0:0.1:0.3:19.3:26.8:nil; and 3.7:trace:0.6:26.3:5.5:1.0; respectively. Among the polysaccharides, only DAP-4IIa-1 reacted with beta-glucosyl-Yariv antigen. Methylation analysis indicated that DAP-4I-1a mainly comprised 4-linked Gal and 3-, 4-, and 6-linked Glc, whereas DAP-4IIa-1 consisted mainly of terminal Araf, 3-linked Glc, and 3,6-branched Gal.

Adjuvants, Immunologic↗
PubMed2002

Chair-boat transitions in single polysaccharide molecules observed with force-ramp AFM.

Under a stretching force, the sugar ring of polysaccharide molecules switches from the chair to the boat-like or inverted chair conformation. This conformational change can be observed by stretching single polysaccharide molecules with an atomic force microscope. In those early experiments, the molecules were stretched at a constant rate while the resulting force changed over wide ranges. However, because the rings undergo force-dependent transitions, an experimental arrangement where the force is the free variable introduces an undesirable level of complexity in the results. Here we demonstrate the use of force-ramp atomic force microscopy to capture the conformational changes in single polysaccharide molecules. Force-ramp atomic force microscopy readily captures the ring transitions under conditions where the entropic elasticity of the molecule is separated from its conformational transitions, enabling a quantitative analysis of the data with a simple two-state model. This analysis directly provides the physico-chemical characteristics of the ring transitions such as the width of the energy barrier, the relative energy of the conformers, and their enthalpic elasticity. Our experiments enhance the ability of single-molecule force spectroscopy to make high-resolution measurements of the conformations of single polysaccharide molecules under a stretching force, making an important addition to polysaccharide spectroscopy.

Elasticity↗
PubMed1973

Complex formation between mycobacterial polysaccharides and fatty acyl-CoA derivatives.

The mycobacterial polysaccharides MMP and MGLP, which contain numerous O-methyl-sugar residues, markedly stimulate fatty acid synthesis catalyzed by a multienzyme complex from Mycobacterium phlei [Ilton, M. et al. (1971) Proc. Nat. Acad. Sci. USA 68, 87-91]. When aqueous solutions containing MMP or MGLP and palmitoyl-CoA were chromatographed on Sephadex G-75 under conditions that widely separate the individual components, polysaccharide and fatty acyl-CoA were eluted in a single peak, indicating formation of a molecular complex. Similarly, the mycobacterial polysaccharides associate with the CoA derivatives of C(18), C(20), and C(22) acids to yield complexes containing maximally 1 mol of fatty acyl-CoA per mol of polysaccharide. The formation of these novel complexes may result from hydrophobic interactions between the paraffin chains of the acyl-CoA derivatives and O-methyl-sugar residues of the polysaccharides.

Chromatography, Gel↗
PubMed1996

N-Acetylated domains in heparan sulfates revealed by a monoclonal antibody against the Escherichia coli K5 capsular polysaccharide. Distribution of the cognate epitope in normal human kidney and transplant kidney with chronic vascular rejection.

The Escherichia coli K5 capsular polysaccharide has the same (GlcUA-->GlcNAc)n structure as the nonsulfated heparan sulfate/heparin precursor polysaccharide. A monoclonal antibody (mAb 865) against the K5 polysaccharide has been described (Peters, H., Jürs, M., Jann, B., Jann, K., Timmis, K. N., and Bitter-Sauermann, D. (1985) Infect. Immun. 50, 459-466). In this report, we demonstrate the binding of anti-K5 mAb 865 to N-acetylated sequences in heparan sulfates and heparan sulfate proteoglycans but not to heparin. This is shown by direct binding and fluid phase inhibition of mAb 865 in an enzyme-linked immunosorbent assay. In this system we found that the binding of the mAb decreased with increasing sulfate content of the polysaccharide. By testing chemically modified K5 and heparin polysaccharides, we found that each of the modifications that occur during heparan sulfate (HS) synthesis (N-sulfation, C-5 epimerization, and O-sulfation) prevents recognition by mAb 865. Samples of heparan sulfate from human aorta (HS-II) were selectively degraded so as to allow the separate isolation of N-sulfated and N-acetylated block structures. N-Sulfated oligosaccharides (obtained after N-deacetylation by hydrazinolysis followed by nitrous acid deamination at pH 3.9) were not recognized by mAb 865, in contrast to N-acetylated oligosaccharides (obtained after nitrous acid deamination at pH 1.5), although the reactivity was lower than for intact HS-II. Analysis of the latter's pH 1.5 deamination products by gel filtration indicated that a minimal size of 18 saccharide units was necessary for antibody binding. These results lead us to propose bivalent antibody-heparan sulfate interaction, in which both F(ab) domains of the mAb interact with their epitopes, both of which are present in a single large (>/=18 saccharide units) N-acetylated domain and additionally with single epitopes present in two N-acetylated sequences (each <18 saccharide units) bridged by a short N-sulfated domain. Immunohistochemistry with mAb 865 on cryostat sections of normal human kidney tissue, revealed its binding to most but not all renal basement membranes. However, all renal basement membranes contain heparan sulfate, as shown by a mAb against heparitinase-digested heparan sulfate stubs (mAb 3G10). This finding indicates that not all heparan sulfate chains present in basement membranes express the mAb 865 epitopes. Besides the normal distribution, mAb 865 staining was found in fibrotic and sclerotic lesions in vessels, interstitium, and mesangium in transplant kidneys with chronic vascular rejection. Occasionally, a decrease of staining was observed within tubulo-interstitium and glomeruli. These findings show that N-acetylated sequences in heparan sulfates can be demonstrated by anti-K5 mAb 865 in normal and diseased kidneys.

Acetylation↗
PubMed2000

The transport of group 2 capsular polysaccharides across the periplasmic space in Escherichia coli. Roles for the KpsE and KpsD proteins.

The cell surface expression of group 2 capsular polysaccharides involves the translocation of the polysaccharide from its site of synthesis on the inner face of the cytoplasmic membrane onto the cell surface. The transport process is independent of the repeat structure of the polysaccharide, and translocation across the periplasm requires the cytoplasmic membrane-anchored protein KpsE and the periplasmic protein KpsD. In this paper we establish the topology of the KpsE protein and demonstrate that the C terminus interacts with the periplasmic face of the cytoplasmic membrane. By chemical cross-linking we show that KpsE is likely to exist as a dimer and that dimerization is independent of the other Kps proteins or the synthesis of capsular polysaccharide. No interaction between KpsD and KpsE could be demonstrated by chemical cross-linking, although in the presence of both KpsE and Lpp, KpsD could be cross-linked to a 7-kDa protein of unknown identity. In addition, we demonstrate that KpsD is present not only within the periplasm but is also in both the cytoplasmic and outer membrane fractions and that the correct membrane association of KpsD was dependent on KpsE, Lpp, and the secreted polysaccharide molecule. Both KpsD and KpsE showed increased proteinase K sensitivity in the different mutant backgrounds, reflecting conformational changes in the KpsD and KpsE proteins as a result of the disruption of the transport process. Collectively the data suggest that the trans-periplasmic export involves KpsD acting as the link between the cytoplasmic membrane transporter and the outer membrane with KpsE acting to facilitate this transport process.

Bacterial Proteins↗
PubMed1987

Multiple carbohydrate receptors on lymphocytes revealed by adhesion to immobilized polysaccharides.

Phosphomannan polysaccharides and fucoidan, a polymer of fucose 4-sulfate, have been demonstrated to inhibit adhesion of lymphocytes to tissue sections that contain high endothelial venules (Stoolman, L. M., T. S. Tenforde, and S. D. Rosen, 1984, J. Cell Biol., 99:1535-1540). We have investigated the potential cell surface carbohydrate receptors involved by quantitating adhesion of rat cervical lymph node lymphocytes to purified polysaccharides immobilized on otherwise inert polyacrylamide gels. One-sixth of the lymphocytes adhered specifically to surfaces derivatized with PPME (a phosphomannan polysaccharide prepared from Hansenula holstii yeast), whereas up to half of the cells adhered to surfaces derivatized with fucoidan. Several lines of evidence demonstrated that two distinct receptors were involved. Adhesion to PPME-derivatized gels was labile at 37 degrees C (decreasing to background levels within 120 min) whereas adhesion to fucoidan-derivatized gels was stable. Soluble PPME and other phosphomannans blocked adhesion only to PPME-derivatized gels; fucoidan and a structurally related fucan blocked adhesion to fucoidan-derivatized gels. Other highly charged anionic polysaccharides, such as heparin, did not block adhesion to either polysaccharide-derivatized gel. Adhesion to PPME-derivatized gels was dependent on divalent cations, whereas that to fucoidan-derivatized gels was not. The PPME-adherent lymphocytes were shown to be a subpopulation of the fucoidan-adhesive lymphocytes which contained both saccharide receptors. These data reveal that at least two distinct carbohydrate receptors can be found on peripheral lymphocytes.

Animals↗
PubMed1954

Immunochemical studies of antitoxin produced in normal and allergic individuals hyperimmunized with diphtheria toxoid. V. Peculiar electrophoretic configuration of serum proteins and protein-bound polysaccharides in certain antitoxic sera; demonstration of serum changes in certain severe manifestations of allergy.

The method of filter paper electrophoresis was used to study proteins and protein-bound polysaccharides in sera obtained from subjects before and after a single booster dose of diphtheria toxoid, and in sera from allergic subjects. The electrophoretic patterns of precipitating antitoxic sera resembled those found in normal non-immune sera. However, skin-sensitizing antitoxic sera were distinguished by a relatively large beta globulin component and a small or indistinct alpha(2) globulin. Fusion of both components was present in some sera containing this variety of antitoxin. Considerable amounts of serum-bound polysaccharides in these sera migrated relatively slowly in contrast to the behavior of polysaccharides of precipitating antitoxic sera which migrated faster when tested under similar conditions. Alterations in proteins and carbohydrates were most readily observed in specimens containing high titers of antitoxin. There were no demonstrable differences between the electrophoretic behavior of sera obtained from subjects before or after immunization with toxoid. Electrophoretic patterns of serum from allergic subjects who developed marked eosinophilia showed attenuation of the alphas globulin associated with a relative preponderance of slow migrating protein-bound polysaccharides. These alterations were not present in sera obtained from the same persons before and after the development of eosinophilia. Changes in the proteins and polysaccharides could not be demonstrated with consistency in subjects with mild to moderate hay-fever symptoms. One person who developed severe acute hay-fever symptoms showed alterations in the beta and alpha(2) globulins. Rheumatic fever subjects showed no unusual changes in the distribution of serum components. However, transition from the acute process to convalescence is graphically demonstrated by the marked decreases in gamma and alpha globulins and in protein-bound carbohydrates.

Antitoxins↗
PubMed1960

Immunological studies on a C polysaccharide complex of group A streptococci having a direct toxic effect on connective tissue.

A macromolecular complex of C polysaccharide and peptide derived from Group A streptococcal cells produces a multinodular, remittent, and intermittent lesion of dermal connective tissue following a single intradermal injection. This lesion is greatly modified, both in the gross and microscopically, in rabbits hyperimmunized with a Group A streptococcal vaccine. The immune serum, absorbed to yield only antibodies against C polysaccharide as indicated by agar diffusion techniques, will precipitate and neutralize the toxic material. This neutralization and in vitro precipitation can be inhibited with formamide-isolated C polysaccharide hapten and with N-acetylglucosamine, the primary directive group of this antigen. This clearly demonstrates that antibodies against the group-specific C polysaccharide are responsible for resistance to this toxic material. The immunological and other properties of the toxic C polysaccharide complex, the fact that it is a product of Group A streptococci, the gross and microscopic features of the experimental lesion produced with this substance, and the observations on the chronic course of the experimental lesion, indicate that this toxic material should be investigated as a possible factor in the pathogenesis of the non-suppurative sequelae associated with Group A streptococci.

Animals↗
PubMed1966

Studies on the induction of immunological unresponsiveness to pneumococcal polysaccharide in mice.

1. Comparison of dose-response curves indicated that preimmunized animals were slightly more susceptible to the induction of immunological paralysis with pneumococcal polysaccharide than were normal mice. The results also indicated that the paralysis threshold was unaltered by preimmunization. 2. Transient desensitization of immunized mice could be achieved by an amount of polysaccharide far less than that required to induce paralysis. 3. A transient phase of weak immunity was detected prior to the onset of paralysis when induced by relatively low paralyzing doses of polysaccharide. 4. No "low dose" zone of paralysis (analogous to that obtainable with certain protein antigens) could be elicited with pneumococcal polysaccharide. 5. Massive proliferation of lymphoreticular tissues induced by Corynebacterium parvum failed to raise the threshold for paralysis induction, but amplified the immune response over the entire dose-response curve. Similarly, C. parvum failed to abrogate an established state of paralysis. The results suggest that the induction of polysaccharide paralysis is related to the concentration of antigen in the animal and is not modified by the number of immunologically competent cells.

Animals↗
PubMed1968

Capsulation of pneumococcus with soluble C-like (Cs) polysaccharide. I. Biological and genetic properties of Cs pneumococcal strains.

Capsulated mutants of pneumococcus producing a capsule of soluble polysaccharide related immunologically to the C or cell wall polysaccharide of pneumococcus have been isolated from several noncapsulated variants of this organism. The capsular material of these strains reacts with antisera both to homologous strains and to noncapsulated strains of pneumococcus and with human C-reactive protein. C-reactive protein has been shown to give a positive capsular precipitin or Quellung reaction with C(s) pneumococcal variants and to agglutinate them. The genetic locus which determines the production of C(s) polysaccharide is situated in a region of the pneumococcal chromosome distinct from that controlling normal capsular polysaccharide synthesis. Binary and ternary capsulated pneumococci, one of the capsular components of which is C(s) polysaccharide, have been isolated following DNA-mediated transformation.

Agglutination Tests↗
PubMed1969

Human immunity to the meningococcus. V. The effect of immunization with meningococcal group C polysaccharide on the carrier state.

Purified meningococcal polysaccharides were administered to army recruits. No adverse reactions were observed in 145 men who received group C polysaccharide, and in 53 men who were injected with group A polysaccharide. Hemagglutinating and bactericidal activity developed in the sera of all individuals with the exception of two recruits injected with A polysaccharide. During the 6 wk period of observation, the proportion of unvaccinated recruits who acquired group C meningococci in the three companies studied was 38, 42, and 69 per cent. A significantly lower proportion of the individuals vaccinated with group C polysaccharide acquired group C meningococci; 4.6, 24, and 31 per cent respectively.

Adult↗
PubMed1970

The relationship between group A and group C meningococcal polysaccharides and serum opsonins in man.

The interaction in vitro between human granulocytes and meningococci in the presence of sera from volunteers immunized by Gotschlich et al. with purified group A and group C meningococcal polysaccharides was studied. Phagocytosis of meningococci did not occur in the presence of preimmunization sera. In all volunteers tested, group-specific opsonins were detected in groups A and C polysaccharide antisera. Opsonic activity appeared within 1 wk after immunization and persisted for at least 14 months. Titers of opsonic activity ranged from 1:20 to 1:320; highest titers were noted in 2-4 wk antisera. Meningococcal opsonins were detected in both 19S and 7S immunoglobulins. Opsonic activity in low-titer antisera depended on heat-labile factors present in both normal and immune sera, whereas phagocytosis was observed in the presence of heat-inactivated high-titer antisera. Phagocytosis of group A meningococci in the presence of certain group A polysaccharide antisera was inhibited by N-acetyl mannosamine, but not by mannose, mannosamine, N-acetyl glucosamine, N-acetyl galactosamine, or N-acetyl neuraminic acid. Absorption studies with sera from patients with natural meningococcal infections revealed that these polysaccharides are the major antiphagocytic determinants for group A and group C meningococci. These studies are consistent with previous reports suggesting that immunization with group A and group C polysaccharides may well provide group-specific protection against meningococcal infections.

Antibodies↗