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At least 19 recordsLinked to original sources
PubMed2000

Activation of soluble polysaccharides with 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP) for use in protein-polysaccharide conjugate vaccines and immunological reagents. II. Selective crosslinking of proteins to CDAP-activated polysaccharides.

Covalently linking protein to polysaccharides converts the anti-polysaccharide immune response from a T-cell independent response to one which is T-cell dependent. The organic cyanylating reagent 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP) (Vaccine 14:190, 1996) has been used to activate polysaccharides, which can then be reacted with spacer reagents or directly with protein. We wished to explore ways in which proteins could be linked to CDAP-activated polysaccharides to conjugate in a more controlled and selective fashion. To this end, we examined the reaction of nucleophilic amino acids with CDAP-activated polysaccharides under basic and acidic conditions. We found that lysine, cysteine and histidine but not methionine, serine or tyrosine conjugated to CDAP-activated dextran. We also examined the reaction of various spacer reagents with CDAP-activated dextran as a function of pH. The addition of hexanediamine was highly pH dependent and maximal at pH 9.3. In contrast, the addition of adipic dihydrazide, which has a pKa of ca 2.5 was essentially independent of pH. By performing the conjugation reaction at pH 5, we were able to selectively couple hydrazides even in the presence of high concentrations of amines. Proteins derivatized with limited numbers of hydrazides could be conjugated to CDAP-activated polysaccharides at pH5, where the native protein was not reactive. Proteins could be derivatized with hydrazides on carboxyls using adipic dihydrazide and a water soluble carbodiimide or on amines using a mild two-step reaction. Tetanus toxoid-pneumococcal type 14 conjugates produced by coupling hydrazide-derivatized tetanus toxoid under acidic conditions induced anti-polysaccharide antibodies at titers comparable to that stimulated by conjugates produced using a basic coupling pH. Our data suggest that crosslinking was occurring only with the limited number of hydrazides on the protein and that we achieved limited and selective crosslinking between the protein and CDAP-activated polysaccharide. This work also demonstrates that CDAP-mediated conjugation to polysaccharides can be applied even to very pH sensitive proteins and polysaccharides.

Amines↗
PubMed2000

Structures of two cell wall-associated polysaccharides of a Streptococcus mitis biovar 1 strain. A unique teichoic acid-like polysaccharide and the group O antigen which is a C-polysaccharide in common with pneumococci.

The cell wall of Streptococcus mitis biovar 1 strain SK137 contains the C-polysaccharide known as the common antigen of a closely related species Streptococcus pneumoniae, and a teichoic acid-like polysaccharide with a unique structure. The two polysaccharides are different entities and could be partially separated by gel chromatography. The structures of the two polysaccharides were determined by chemical methods and by NMR spectroscopy. The teichoic acid-like polymer has a heptasaccharide phosphate repeating unit with the following structure: The structure neither contains ribitol nor glycerol phosphate as classical teichoic acids do, thus we have used the expression teichoic acid-like for this polysaccharide. The following structure of the C-polysaccharide repeating unit was established: where AAT is 2-acetamido-4-amino-2,4, 6-trideoxy-D-galactose. It has a carbohydrate backbone identical to that of one of the two structures of C-polysaccharide previously identified in S. pneumoniae. C-polysaccharide of S. mitis is characterized by the presence, in each repeating unit, of two residues of phosphocholine and both galactosamine residues in the N-acetylated form. Immunochemical analysis showed that C-polysaccharide constitutes the Lancefield group O antigen. Studies using mAbs directed against the backbone and against the phosphocholine moiety of the C-polysaccharide revealed several different patterns of these epitopes among 95 S. mitis and Streptococcus oralis strains tested and the exclusive presence of the group O antigen in the majority of S. mitis biovar 1 strains.

Carbohydrate Conformation↗
PubMed1985

Purification, characterization and immunological properties of the capsular polysaccharide of Pasteurella haemolytica serotype T15: its identity with the K62 (K2ab) capsular polysaccharide of Escherichia coli and the capsular polysaccharide of Neisseria meningitidis serogroup H.

Capsular polysaccharide from two strains of Pasteurella haemolytica serotype T15 was purified and characterized by chemical analysis and NMR spectroscopy. The polymer, a teichoic acid, proved to be very similar in structure to the capsular polysaccharide of P. haemolytica serotype T4 and identical to the previously described K62 (K2ab) capsular polysaccharide of Escherichia coli, and the capsular polysaccharide of Neisseria meningitidis serotype H, i.e. ----(2-glycerol-3)----(phosphate)----(4-alpha-D-galactopyranose -1)---- with partial O-acetylation on the galactose residues. Electron microscopy with Protein A-gold labelled antisera showed that the polysaccharide was peripherally located on the surface of all three organisms. Chemical removal of O-acetyl groups from the polysaccharide yielded a structure identical to that previously described for E. coli K2 (K2a). Both O-acetylated and de-O-acetylated P. haemolytica T15 polymers, when absorbed on to sheep erythrocytes in passive haemagglutination assays, yielded identical antibody titres with sera raised against P. haemolytica T15, E. coli K2 or N. meningitidis H whole cells. De-O-acetylation of the Pasteurella polysaccharide influenced its precipitability with immune sera, but this could not be related to the absence of O-acetyl groups because the non-acetylated E. coli K2 polymer readily precipitated with a line of 'identity' with the acetylated P. haemolytica T15 polymer.

Escherichia coli↗
PubMed2002

Polysaccharide analysis using carbohydrate gel electrophoresis: a method to study plant cell wall polysaccharides and polysaccharide hydrolases.

A method to characterize plant cell wall polysaccharides is presented. The complexity of the polymer structures and the large number of different charged and uncharged monosaccharides that make up plant polysaccharides have previously made analysis technically demanding and laborious. Polysaccharide analysis using carbohydrate gel electrophoresis (PACE) relies on derivatization of reducing ends of sugars and oligosaccharides with a fluorophore, followed by electrophoresis under optimized conditions in polyacrylamide gels. We show that PACE is a sensitive and simple tool for studying the monosaccharide composition of polysaccharides and of cell wall preparations. In combination with specific hydrolases, it can be used to analyze the structure of polysaccharides. Moreover, the specificity and kinetics of the plant polysaccharide hydrolases themselves can be quickly and effectively studied. PACE can detect as little as 500 fmol of monosaccharides and 100 fmol of oligosaccharides, and it is fast and quantitative.

Arabidopsis↗
PubMed2002

Gamma 3 gene-disrupted mice selectively deficient in the dominant IgG subclass made to bacterial polysaccharides. II. Increased susceptibility to fatal pneumococcal sepsis due to absence of anti-polysaccharide IgG3 is corrected by induction of anti-polysaccharide IgG1.

Bacterial polysaccharides (PS) are type 2 T-independent Ags that elicit Abs restricted in isotype to IgM and predominantly IgG2 in humans and IgM, and IgG3 in mice. Humans with IgG2 subclass deficiency are susceptible to sinus and pulmonary infections with PS-encapsulated bacteria. We previously developed an IgG3-deficient mouse by disrupting the gamma3 H chain constant region gene via targeted mutagenesis. Mutant mice lacking IgG3 were backcrossed for 10 generations to wild-type (WT) BALB/c mice to generate BALB/c mice that have complete absence of IgG3. WT mice immunized with type 3 Streptococcus pneumoniae capsular PS made anti-PS IgM, IgG3, and small quantities of IgG1, which opsonized S. pneumoniae for killing by polymorphonuclear leukocytes. These mice were protected against death from lethal doses of type 3 S. pneumoniae. In contrast, IgG3(-/-) mice made similar titers of anti-PS IgM and IgG1 as WT mice but no IgG3, and had poorly opsonic sera with significantly increased mortality after S. pneumoniae challenge. Immunization of IgG3(-/-) mice with type 3 S. pneumoniae PS conjugated to carrier protein CRM(197)-elicited IgM and high-titer IgG1 Abs, restored serum opsonization, and gave protection from mortality after S. pneumoniae, challenge comparable to WT mice. We conclude that mice lacking the dominant IgG3 subclass made to bacterial PS are more susceptible to fatal S. pneumoniae sepsis than WT mice, but that IgG1 induced by a S. pneumoniae glycoconjugate can adequately protect against S. pneumoniae sepsis. This model suggests that IgG subclass of anti-PS Ab is an important component of immunity to encapsulated bacteria.

Alleles↗
PubMed1992

The capsular polysaccharide of Bacteroides fragilis comprises two ionically linked polysaccharides.

Recently, we have shown that the capsular polysaccharide of Bacteroides fragilis NCTC 9343 is composed of an aggregate of two discrete large molecular weight polysaccharides (designated polysaccharides A and B). Following disaggregation of this capsular complex by very mild acid treatment, high resolution NMR spectroscopy demonstrated that polysaccharides A and B consist of highly charged repeating unit structures with unusual substituent groups (Baumann, H., Tzianabos, A. O., Brisson, J.-R., Kasper, D.L., and Jennings, H.J. (1992) Biochemistry 31, 4081-4089). Presently, we report that the capsular polysaccharide of B. fragilis represents a complex structure that is formed as a result of ionic interactions between polysaccharides A and B. Electron microscopy of immunogold-labeled organisms (with monoclonal antibodies specific for polysaccharides A and B) demonstrated that the two polysaccharides are co-expressed on the cell surface of B. fragilis. We have shown that the purified capsule complex is made up exclusively of polysaccharide A and polysaccharide B (no other macromolecular structure was detected) in a 1:3.3 ratio and that disaggregation of this complex into the native forms of the constituent polysaccharides could be accomplished by preparative isoelectric focusing. Structural analyses of the native polysaccharides A and B showed that they possessed the same repeating unit structures as the respective acid-derived polysaccharides. The ionic nature of the linkage between polysaccharides A and B was demonstrated by reassociation of the native polysaccharides to form an aggregated polymer comparable to the original complex. The distinctive composition of this macromolecule may provide a rationale for the unusual biologic properties associated with the B. fragilis capsular polysaccharide.

Bacteroides fragilis↗
PubMed1977

Non-encapsulated variant of Cryptococcus neoformans. II. Surface receptors for cryptococcal polysaccharide and their role in inhibition of phagocytosis by polysaccharide.

The binding of cryptococcal polysaccharide to a non-encapsulated strain of Cryptococcus neoformans was studied. Binding of purified polysaccharide to the yeast was determined by inhibition of phagocytosis and by indirect immunofluorescence techniques. The ability of cryptococcal polysaccharide to prevent phagocytosis of the non-encapsulated strain appears to be directly related to adherence of polysaccharide to the yeast via specific receptors on the cell surface. Addition of varying doses of cryptococcal polysaccharide to non-encapsulated yeast cells inhibited phagocytosis only at polysaccharide concentrations at which the polysaccharide could be demonstrated on the yeast surface by immunofluorescence. Macrophages treated with cryptococcal polysaccharide had no detectable amounts of cryptococcal polysaccharide adherent to their surface, and they had a normal ability to phagocytize the yeast. Kinetic studies showed that inhibition of phagocytosis is directly related to the presence of cryptococcal polysaccharide at the yeast surface rather than to some indirect effect by the polysaccharide on serum components necessary for phagocytosis. Purified polysaccharide from C. neoformans serotypes A, B, C, and D bound to the yeast, but type III pneumococcal polysaccharide did not inhibit phagocytosis of the nonencapsulated yeast. Cryptococcal polysaccharide did not bind to cells of Candida albicans, C. pseudotropicalis, Torulopsis sp., Rhodotorula sp., or Saccharomyces cerevisiae.

Ascitic Fluid↗
PubMed1995

Actinobacillus actinomycetemcomitans Y4 capsular-polysaccharide-like polysaccharide promotes osteoclast-like cell formation by interleukin-1 alpha production in mouse marrow cultures.

The mechanism of osteoclast-like cell formation induced by periodontopathic bacterium Actinobacillus actinomycetemcomitans Y4 (serotype b) capsular-polysaccharide-like polysaccharide (capsular-like polysaccharide) was examined in a mouse bone marrow culture system. When mouse bone marrow cells were cultured with A. actinomycetemcomitans Y4 capsular-like polysaccharide for 9 days, many multinucleated cells were formed. The multinucleated cells showed several characteristics of osteoclasts, including tartrate-resistant acid phosphatase (TRACP) and the ability to resorb the calcified dentine. In this study, we examined the effects of antisera to interleukins on the formation of osteoclast-like cells induced by A. actinomycetemcomitans Y4 capsular-like polysaccharide. Monospecific anti-mouse recombinant interleukin-1 alpha (rIL-1 alpha) serum completely inhibited the formation of osteoclast-like cells in the presence of A. actinomycetemcomitans Y4 capsular-like polysaccharide. However, anti-mouse rIL-1 beta and anti-mouse rIL-6 sera showed no effect on osteoclast-like cell formation. IL-1 receptor antagonist significantly inhibited the osteoclast-like cell formation mediated by A. actinomycetemcomitans Y4 capsular-like polysaccharide in mouse marrow cultures. The bioactive IL-1 was detected in the culture media of mouse bone marrow cells stimulated with A. actinomycetemcomitans Y4 capsular-like polysaccharide. These results indicate that IL-1 alpha is involved in the mechanism of the formation of osteoclast-like cells induced by A. actinomycetemcomitans Y4 capsular-like polysaccharide. We sought to determine whether osteoclast-like cell formation induced by A. actinomycetemcomitans Y4 capsular-like polysaccharide could be modulated by the protein kinase inhibitors H8 and HA1004. The formation of osteoclast-like cells was suppressed by H8 and HA1004. These findings suggest that the signals by protein kinases may regulate osteoclast-like cell formation induced by A. actinomycetemcomitans Y4 capsular-like polysaccharide. Furthermore, a correlation between IL-1 alpha and prostaglandin E2 in the osteoclast recruitment induced by A. actinomycetemcomitans Y4 capsular-like polysaccharide is discussed.

Acid Phosphatase↗
PubMed1990

Type 6 and 19 pneumococcal polysaccharides coupled to erythrocytes elicit pneumococcal cell wall-specific primary IgM responses and capsular polysaccharide-specific secondary IgG responses.

Previous results have shown that the primary murine antibody responses to vaccine preparations of type 6 (S6; Danish type 6A) or type 19 (S19; Danish type 19F) pneumococcal capsular polysaccharides consist entirely of IgM antipneumococcal cell wall carbohydrate (PnC)-specific antibodies. No capsular polysaccharide-specific IgM antibodies were detectable by plaque-forming cell or enzyme-linked immunosorbent assay techniques. In this report, antibodies specific for S6 and S19 capsular polysaccharides were induced in secondary responses to chicken erythrocyte (CRBC) conjugates of S6 and S19. Essentially all detectable IgG produced in the secondary response was capsular polysaccharide specific and included all subclasses of IgG. In contrast, all detectable IgM produced in the primary response to S6-CRBC and S19-CRBC, and the IgM produced in the secondary response to S6-CRBC was not capsular polysaccharide specific since it reacted with PnC. Thus, there is a major change in the specificity of the primary IgM response compared to the secondary IgG response of mice immunized with S6-CRBC or S19-CRBC. Injection of PnC or any PnC-containing polysaccharide prior to immunization with S6-CRBC or S19-CRBC resulted in suppression of the primary IgM response. In contrast, only the capsular polysaccharide used in the immunizing polysaccharide-erythrocyte conjugate suppressed induction of the capsular polysaccharide-specific secondary IgG response. These results suggest that S6 and S19 capsular polysaccharide-specific IgG-producing memory B cells derive from capsular polysaccharide-specific precursors which do not produce detectable antibody after primary immunization.

Animals↗
PubMed1981

Further Studies of the polysaccharide of Klebsiella pneumoniae possessing strong adjuvanticity. I. Production of the adjuvant polysaccharide by noncapsulated mutant.

In culture fluid, Klebsiella pneumoniae type 1 Kasuya strain produces polysaccharide exhibiting a strong adjuvant effect. The active substance responsible for the strong adjuvant effect of the polysaccharide isn ot its acidic polysaccharide fraction (the type-specific capsular antigen) but the neutral polysaccharide fraction. In the present study, a mutant which did not produce the type-specific capsular polysaccharide was isolated from ultraviolet-irradiated cells of K. pneumoniae type 1 Kasuya strain which had been labeled with leucine-requiring marker by selecting unagglutinable cells with the antiserum to he type-specific capsular polysaccharide. Serological tests showed that the type-specific acidic capsular polysaccharide was present neither on the cells surface nor in the culture fluid of the mutant. Electron microscopically, the mutant did not possess any capsular material. On the other hand, nearly an equal amount of neutral polysaccharide antigen as produced in culture fluids of the noncapsulated mutant polysaccharide antigen was produced in culture fluids of te noncapsulated mutant and the parent strain. The neutral polysaccharide antigen produced by the noncapsulated mutant exhibited the same degree of strong adjuvant effect on antibody response to bovine gammaglobulin in mice as that produced by the parent strain. The relationship between the neutral polysaccharide antigen in culture fluid and the O antigen of K. pneumoniae was discussed.

Adjuvants, Immunologic↗
PubMed1986

Induction of meningococcal group B polysaccharide-specific IgG antibodies in mice by using an N-propionylated B polysaccharide-tetanus toxoid conjugate vaccine.

Conjugation of the group B meningococcal polysaccharide to tetanus toxoid failed to substantially enhance its immunogenicity in mice. Therefore, additional chemical manipulation of the basic structure of the group B meningococcal polysaccharide was attempted, on the premise that a synthetically derived artificial antigen might be capable of modulating the immune response in mice to produce elevated levels of cross-reactive group B meningococcal polysaccharide-specific antibodies. To achieve this, the antigenicity of the modified polysaccharide to group B meningococcal polysaccharide-specific antibodies had to be preserved, and this criterion could only be satisfied in modifications in which the carboxylate and N-carbonyl groups of the sialic acid residues of polysaccharide remained intact. Therefore, the most successful modifications were accomplished by N-deacetylation of the group B meningococcal polysaccharide with strong base to yield a precursor that could then be N-acetylated or N-arylated with different substituents. For example, the introduction of N-propionyl groups, followed by conjugation of the resultant N-propionylated group B meningococcal polysaccharide to tetanus toxoid, yielded an antigen that when injected in mice induced in them high levels of cross-reactive group B meningococcal polysaccharide-specific IgG antibodies. The T cell dependency of this antigen was established when it was demonstrated that the levels of these B polysaccharide-specific antibodies could be significantly boosted by using both the N-propionylated- and native N-acetylated-group B meningococcal polysaccharide-tetanus toxoid conjugates.

Animals↗
PubMed1996

Activation of soluble polysaccharides with 1-cyano-4-dimethylaminopyridinium tetrafluoroborate for use in protein-polysaccharide conjugate vaccines and immunological reagents.

Neonates have poor immune responses to type 2 T-cell independent antigens (TI-2), such as polysaccharides and immunization of human infants with these antigens does not induce protective levels of serum antibodies. Conjugating proteins to TI-2 antigens converts the immune response to one which is T-cell dependent. We used an organic cyanylating reagent, 1-cyano-4-dimethylaminopyridinium tetrafluroborate (CDAP), to activate polysaccharides, in water, and subsequently react them with hexanediamine, in preparation for coupling proteins to the polysaccharide. CDAP activation of polysaccharide is rapid (< 2 min) and efficient. CDAP can be used to activate polysaccharides of diverse chemical natures, including dextrans and pneumococcal types 6, 14, 19 and 23. The critical parameters in CDAP activation of polysaccharides were the reagent concentrations and the pH. Activation can be performed over a broad alkaline pH range, with an optimum of pH 9-10. Furthermore, proteins can be coupled to CDAP-activated polysaccharides without the use of a spacer. Direct conjugation of protein to CDAP-activated polysaccharides can be performed under mildly alkaline conditions (pH 7-9). These conditions allow CDAP to be used with alkaline-sensitive polysaccharides and proteins. Mice immunized with BSA-pneumococcal type 14 polysaccharides (Pn14) conjugates, prepared either by direct conjugation or via a spacer, had high anti-Pn14 and anti-BSA serum antibody IgG1 titers, whereas no IgG1 antibody was induced to the unconjugated components. The ease of use and mild activating conditions should prove of value in using CDAP to prepare conjugate vaccines, as well as other immunologically useful reagents.

Animals↗
PubMed1995

Immunoblot analysis of bacterial polysaccharides: application to the type-specific polysaccharides of Streptococcus suis and Streptococcus agalactiae.

A method for the immunoblot analysis of the type-specific capsular polysaccharides of streptococci was developed. The capsular polysaccharides were extracted by sonication and subjected to polyacrylamide gel electrophoresis in the absence of sodium dodecyl sulphate (SDS). After electrophoresis the polysaccharides were transferred to charged PVDF-N membranes and probed with the type specific antibodies. A characteristic ladder-like pattern of polysaccharide bands specific for the serotype (1, 2, 4, 7) was observed for capsular extracts of Streptococcus suis. Human immune sera against type-specific group B streptococcal polysaccharides reacted most strongly with the immunizing polysaccharide type (Ia, II, III). The previously observed crossreactions between the group B streptococcal type-specific capsular preparations were shown to be due to binding to the isomeric polysaccharide molecules. Thus, gel electrophoresis combined with immunoblot analysis seems to provide a novel method for the molecular and immunochemical characterization of bacterial polysaccharides and for the study of the specificity and properties of antibodies to capsular polysaccharides.

Animals↗
PubMed1987

Immunologic priming to capsular polysaccharide in infants immunized with Haemophilus influenzae type b polysaccharide-Neisseria meningitidis outer membrane protein conjugate vaccine.

Thirty children vaccinated at 2 to 17 months of age with Haemophilus influenzae type b polysaccharide linked to a partially purified 40,000 dalton outer membrane protein of Neisseria meningitidis were revaccinated 10 to 14 months later with conventional H. influenzae type b polysaccharide vaccine. The geometric mean anti-type b antibody concentration before reimmunization was 0.68 micrograms/mL, and rose to 31 micrograms/mL in sera obtained 1 month later. The mean level after immunization was not significantly different than that in sera from 12 adults immunized with type b polysaccharide vaccine (51 micrograms/mL, P = 0.3), and was 10-fold higher than that of 13 control children immunized with type b polysaccharide for the first time (2.7 micrograms/mL, P less than 0.001). The IgG responses of the children first given conjugate vaccine and then conventional type b polysaccharide vaccine were of a similar magnitude as those in the immunized adults. Further, the children maintained high levels of serum antibody 6 to 8 months later. Ten other children vaccinated in infancy with conjugate vaccine, and again with conjugate vaccine 10 to 15 months later, showed similar antibody responses to those of the group given conjugate vaccine in infancy, and booster with conventional polysaccharide vaccine. Thus vaccination with H. influenzae type b polysaccharide-outer membrane protein conjugate vaccine primes the immune system to an IgG memory antibody response to either type b polysaccharide or conjugate vaccine. Post-booster sera from all children tested showed high titers of functional activity in a complement-mediated bactericidal assay. These data suggest that protection of most infants from type b Haemophilus disease may be achieved by a combination of immunization at 2 to 4 months of age with this conjugate vaccine, and reimmunization 1 year later with conjugate or conventional type b polysaccharide vaccine.

Adult↗
PubMed1984

Affinity purification of mycobacterial polymethyl polysaccharides and a study of polysaccharide-lipid interactions by 1H NMR.

Mycobacterial polymethyl polysaccharides, which bind long-chain fatty acids tightly [Ballou, C.E. (1981) Pure Appl. Chem. 53, 107-112], have been purified on a preparative scale by use of an affinity column packing consisting of (palmitoylamino)alkylsilyl silicate. The relatively large amount of material obtained in this way has allowed a study of the polysaccharide-lipid interactions at millimolar concentrations. The anomeric protons for all of the alpha 1----4-linked hexose units in the mycobacterial methylglucose polysaccharide occur in an envelope centered at delta 5.40, and, on titration with hexadecyltrimethylammonium bromide, the majority of these resonances move upfield to about delta 5.15. This shift is consistent with a change in the polysaccharide from a less ordered chain to one that has a significant proportion of helical conformation, and it is probable that the alkyl chain is included in the coiled portion of the polysaccharide in a manner analogous to the interaction of methylmannose polysaccharide with palmitic acid [Yabusaki, K. K., Cohen, R. E., & Ballou, C. E. (1979) J. Biol. Chem. 254, 7282-7286]. The native methylglucose lipopolysaccharide, which contains several short-chain acyl groups as well as an esterified octanoyl group, has an anomeric proton nuclear magnetic resonance spectrum similar to that of the methylglucose polysaccharide-hexadecyltrimethylammonium bromide complex. This suggests that the acylation stabilizes the polysaccharide chain in the same conformation it assumes when complexed to a long-chain lipid. Thus, acylation of the methylglucose polysaccharide could have an important role in regulating its shape and lipid-binding properties.

Cetrimonium↗
PubMed1985

Human immune responses to polysaccharide antigens: an analysis of bacterial polysaccharide vaccines in infants.

Mechanisms of human immunity to polysaccharide encapsulated bacteria and the development and testing of the currently available purified polysaccharide bacterial vaccines are reviewed. These vaccines appear to be poorly immunogenic in infants under the age of two years--those at greatest risk for infection. In an effort to understand the poor responses of infants, the human immune response to polysaccharide antigens was characterized in more detail. Using pneumococcal polysaccharide type 3 as an example, it appears that human polysaccharide antibody responses are analogous to the type 2 T cell independent responses defined in the murine system. These studies suggest that the deficient polysaccharide response of human infants is due to a deficiency in maturation of distinct B lymphocyte subpopulations, as well as imbalanced T regulatory influences. The development of vaccines containing the purified capsular polysaccharides of S. pneumoniae, H.influenzae, and N. meningitidis during the past decade offered promise for the prevention of the major causes of bacterial sepsis and meningitis during childhood. The fulfillment of that promise was thwarted by the unrecognized complexities of human antibody responses to polysaccharide antigens. Continued vigorous research in this area has led us to a better understanding of the cellular requirements and immunoregulation of human polysaccharide antibody responses and has given us a clear direction for the pursuit of an effective means for immunization of infants.

Adult↗