Structure of the carbohydrate chain of free secretory component from human milk.

Secretory component from human milk was found to contain 23.4% carbohydrate, which includes galactose, mannose, fucose, glucosamine, and sialic acid. Secretory component could be degraded by pronase or base-borohydride to yield the same, single type of carbohydrate chain. In the glycopeptide produced by pronase digestion, aspartic acid was the only amino acid present in molar quantities after amino acid analysis, which suggests that the carbohydrate moiety is linked to the polypeptide chain at asparagine residues. The positions of links between the various sugar units were studied by methylation analyses of: secretory component, periodate-oxidized and reduced secretory component, the fragment produced by base-borohydride treatment, and the pronase glycopeptide after treatment with specific glycosidases. Sugars released from the glycopeptide by various glycosidases were also quantitated. From the results of these studies a branched chain structure was assigned to the carbohydrate chain of secretory component.     

Identification and Characterization of Bacterial Vaginosis-Associated Pathogens Using a Comprehensive Cervical-Vaginal Epithelial Coculture Assay

Bacterial vaginosis (BV) is the most commonly treated female reproductive tract affliction, characterized by the displacement of healthy lactobacilli by an overgrowth of pathogenic bacteria. BV can contribute to pathogenic inflammation, preterm birth, and susceptibility to sexually transmitted infections. As the bacteria responsible for BV pathogenicity and their interactions with host immunity are not understood, we sought to evaluate the effects of BV-associated bacteria on reproductive epithelia. Here we have characterized the interaction between BV-associated bacteria and the female reproductive tract by measuring cytokine and defensin induction in three types of FRT epithelial cells following bacterial inoculation. Four BV-associated bacteria were evaluated alongside six lactobacilli for a comparative assessment. While responses differed between epithelial cell types, our model showed good agreement with clinical BV trends. We observed a distinct cytokine and human β-defensin 2 response to BV-associated bacteria, especially Atopobium vaginae, compared to most lactobacilli. One lactobacillus species, Lactobacillus vaginalis, induced an immune response similar to that elicited by BV-associated bacteria, stimulating significantly higher levels of cytokines and human β-defensin 2 than other lactobacilli. These data provide an important prioritization of BV-associated bacteria and support further characterization of reproductive bacteria and their interactions with host epithelia. Additionally, they demonstrate the distinct immune response potentials of epithelial cells from different locations along the female reproductive tract.     

Impact of Bacterial Vaginosis,as Assessed by Nugent Criteria and Hormonal Status on Glycosidases and Lectin Binding in Cervicovaginal Lavage Samples

The objective of this study was to evaluate the impact of hormonal status and bacterial vaginosis (BV) on the glycosidases present and glycosylation changes as assessed by lectin binding to cervicovaginal lavage constituents. Frozen cervicovaginal lavage samples from a completed study examining the impact of reproductive hormones on the physicochemical properties of vaginal fluid were utilized for the present study. In the parent study, 165 women were characterized as having BV, intermediate or normal microflora using the Nugent criteria. The presence of glycosidases in the samples was determined using quantitative 4-methyl-umbelliferone based assays, and glycosylation was assessed using enzyme linked lectin assays (ELLA). Women with BV had elevated sialidase, α-galactosidase, β-galactosidase and α-glucosidase activities compared to intermediate or normal women (P<0.001, 0.003, 0.006 and 0.042 respectively). The amount of sialic acid (Sambucus nigra, P = 0.003) and high mannose (griffithsin, P<0.001) were reduced, as evaluated by lectin binding, in women with BV. When the data were stratified according to hormonal status, α-glucosidase and griffithsin binding were decreased among postmenopausal women (P<0.02) when compared to premenopausal groups. These data suggest that both hormonal status and BV impact the glycosidases and lectin binding sites present in vaginal fluid. The sialidases present at increased levels in women with BV likely reduce the number of sialic acid binding sites. Other enzymes likely reduce griffithsin binding. The alterations in the glycosidase content, high mannose and sialic acid binding sites in the cervicovaginal fluid associated with bacterial vaginosis may impact susceptibility to viruses, such as HIV, that utilize glycans as a portal of entry.     

Secretory IgA N- and O-glycans provide a link between the innate and adaptive immune systems

Secretory IgA (SIgA) is a multi-polypeptide complex consisting of a secretory component (SC) covalently attached to dimeric IgA containing one joining (J) chain. We present the analysis of both the N- and O-glycans on the individual peptides from this complex. Based on these data, we have constructed a molecular model of SIgA1 with all its glycans, in which the Fab arms form a T shape and the SC is wrapped around the heavy chains. The O-glycan regions on the heavy (H) chains and the SC N-glycans have adhesin-binding glycan epitopes including galactose-linked beta1-4 and beta1-3 to GlcNAc, fucose-linked alpha1-3 and alpha1-4 to GlcNAc and alpha1-2 to galactose, and alpha2-3 and alpha2-6-linked sialic acids. These glycan epitopes provide SIgA with further bacteria-binding sites in addition to the four Fab-binding sites, thus enabling SIgA to participate in both innate and adaptive immunity. We also show that the N-glycans on the H chains of both SIgA1 and SIgA2 present terminal GlcNAc and mannose residues that are normally masked by SC, but that can be unmasked and recognized by mannose-binding lectin, by disrupting the SC-H chain noncovalent interactions.     

Selective adherence of IgA to murine Peyer's patch M cells: evidence for a novel IgA receptor

M cells represent the primary route by which mucosal Ags are transported across the intestinal epithelium and delivered to underlying gut-associated lymphoid tissues. In rodents and rabbits, Peyer's patch M cells selectively bind and endocytose secretory IgA (SIgA) Abs. Neither the nature of the M cell IgR nor the domains of SIgA involved in this interaction are known. Using a mouse ligated ileal loop assay, we found that monoclonal IgA Abs with or without secretory component, but not IgG or IgM Abs, bound to the apical surfaces of Peyer's patch M cells, indicating that the receptor is specific for the IgA isotype. Human serum IgA and colostral SIgA also bound to mouse M cells. The asialoglycoprotein receptor or other lectin-like receptors were not detected on the apical surfaces of M cells. We used recombinant human IgA1 and human IgA2 Abs and domain swapped IgA/IgG chimeras to determine that both domains Calpha1 and Calpha2 are required for IgA adherence to mouse Peyer's patch M cells. This distinguishes the M cell IgA receptor from CD89 (FcalphaI), which binds domains Calpha2-Calpha3. Finally, we observed by immunofluorescence microscopy that some M cells in the human ileum are coated with IgA. Together these data suggest that mouse, and possibly human, M cells express an IgA-specific receptor on their apical surfaces that mediates the transepithelial transport of SIgA from the intestinal lumen to underlying gut-associated organized lymphoid tissues.     

Bacterial communities of the coronal sulcus and distal urethra of adolescent males

Lactobacillus-dominated vaginal microbiotas are associated with reproductive health and STI resistance in women, whereas altered microbiotas are associated with bacterial vaginosis (BV), STI risk and poor reproductive outcomes. Putative vaginal taxa have been observed in male first-catch urine, urethral swab and coronal sulcus (CS) specimens but the significance of these observations is unclear. We used 16 S rRNA sequencing to characterize the microbiota of the CS and urine collected from 18 adolescent men over three consecutive months. CS microbiotas of most participants were more stable than their urine microbiotas and the composition of CS microbiotas were strongly influenced by circumcision. BV-associated taxa, including Atopobium, Megasphaera, Mobiluncus, Prevotella and Gemella, were detected in CS specimens from sexually experienced and inexperienced participants. In contrast, urine primarily contained taxa that were not abundant in CS specimens. Lactobacilllus and Streptococcus were major urine taxa but their abundance was inversely correlated. In contrast, Sneathia, Mycoplasma and Ureaplasma were only found in urine from sexually active participants. Thus, the CS and urine support stable and distinct bacterial communities. Finally, our results suggest that the penis and the urethra can be colonized by a variety of BV-associated taxa and that some of these colonizations result from partnered sexual activity.     

Mannose-containing oligosaccharides of non-specific human secretory immunoglobulin A mediate inhibition of Vibrio cholerae biofilm formation

The role of antigen-specific secretory IgA (SIgA) has been studied extensively, whereas there is a limited body of evidence regarding the contribution of non-specific SIgA to innate immune defenses against invading pathogens. In this study, we evaluated the effects of non-specific SIgA against infection with Vibrio cholerae O139 strain MO10 and biofilm formation. Seven day old infant mice deficient in IgA (IgA(-/-) mice) displayed significantly greater intestinal MO10 burden at 24 hr post-challenge when compared to IgA(+/+) pups. Importantly, cross-fostering of IgA(-/-) pups with IgA(+/+) nursing dams reversed the greater susceptibility to MO10 infection, suggesting a role for non-specific SIgA in protection against the infection. Since biofilm formation is associated with virulence of MO10, we further examined the role of human non-specific SIgA on this virulence phenotype of the pathogen. Human non-specific SIgA, in a dose-dependent fashion, significantly reduced the biofilm formation by MO10 without affecting the viability of the bacterium. Such an inhibitory effect was not induced by human serum IgA, IgG, or IgM, suggesting a role for the oligosaccharide-rich secretory component (SC) of SIgA. This was supported by the demonstration that SIgA treated with endoglycosidase H, to cleave the high-mannose containing terminal chitobiose residues, did not induce a reduction in biofilm formation by MO10. Furthermore, the addition of free mannose per se, across a wide dose range, induced significant reduction in MO10 biofilm formation. Collectively, these results suggest that mannose containing oligosaccharides within human non-specific secretory IgA can alter important virulence phenotypes of Vibrio cholerae such as biofilm formation, without affecting viability of the microorganism. Such effects may contribute significantly to innate immune defenses against invading pathogens in vivo in the gastrointestinal tract.     

Physicochemical and immunochemical studies on bovine IgA and glycoprotein-a

1. Bovine secretory IgA (SIgA) from colostrum (mol. wt. about 410,000) is composed of four alpha-chains (mol. wt. 61,000), four light chains (mol. wt. 23,000) and one molecule of glycoprotein-a (mol. wt. 70,000-86,000). The alpha-chains are antigenically and physicochemically distinct from the heavy chains of IgM, IgG1 and IgG2 while the light chains are identical to those occurring on other bovine immunoglobulins. Glycoprotein-a and bovine free secretory component are identical and the former name should be abolished. Much of this protein is covalently bonded to IgA. 2. The gel filtration behavior of serum IgA suggests it is a dimer. 3. The elution behavior of IgA and SIgA from ion-exchange columns and the solubility characteristic of SIgA in the presence of Zn2+ are similar to those of human and rabbit IgA. 4. The disc electrophoretic behavior of IgA and SIgA are distinct from IgM, dimeric IgG1, 7-S IgG and glycoprotein-a. Dimeric IgG1 (s20,w = 9.5) is abundant in colostrum and is similar in size to SIgA. 5. Bovine IgA shows physicochemical and immunochemical heterogeneity when studied by gel filtration, disc electrophoresis, immunoelectrophoresis and ultracentrifugational analyses. Lacrimal and nasal SIgA possess antigenic determinants absent on colostral SIgA.     

抗禽流感病毒H5N1 分泌型IgA 在中国仓鼠卵巢细胞中的表达

分泌型IgA (SIgA) 在机体的粘膜免疫中具有重要作用,在外分泌道中比单体IgA和IgG抗体具有更好的抗感染活性。为了表达抗禽流感病毒H5N1人-鼠嵌合分泌型IgA抗体,首先以本室先前构建的稳定表达IgA的中国仓鼠卵巢细胞 (CHO) 细胞系为基础,共转染分泌片和J链表达质粒,然后用抗生素Zeocin选择阳性克隆细胞,利用倍比稀释的方法筛选分泌SIgA的单克隆细胞,通过Western blotting分析培养上清中SIgA的表达情况。结果表明,在CHO细胞中成功表达了SIgA抗体,上述研究为研制分泌型     

Dectin-1 Is Essential for Reverse Transcytosis of Glycosylated SIgA-Antigen Complexes by Intestinal M Cells

Intestinal microfold (M) cells possess a high transcytosis capacity and are able to transport a broad range of materials including particulate antigens, soluble macromolecules, and pathogens from the intestinal lumen to inductive sites of the mucosal immune system. M cells are also the primary pathway for delivery of secretory IgA (SIgA) to the gut-associated lymphoid tissue. However, although the consequences of SIgA uptake by M cells are now well known and described, the mechanisms whereby SIgA is selectively bound and taken up remain poorly understood. Here we first demonstrate that both the Cα1 region and glycosylation, more particularly sialic acid residues, are involved in M cell–mediated reverse transcytosis. Second, we found that SIgA is taken up by M cells via the Dectin-1 receptor, with the possible involvement of Siglec-5 acting as a co-receptor. Third, we establish that transcytosed SIgA is taken up by mucosal CX3CR1⁺ dendritic cells (DCs) via the DC-SIGN receptor. Fourth, we show that mucosal and systemic antibody responses against the HIV p24-SIgA complexes administered orally is strictly dependent on the expression of Dectin-1. Having deciphered the mechanisms leading to specific targeting of SIgA-based Ag complexes paves the way to the use of such a vehicle for mucosal vaccination against various infectious diseases.     

Antigen Binding to Secretory Immunoglobulin A Results in Decreased Sensitivity to Intestinal Proteases and Increased Binding to Cellular Fc Receptors

In intestinal secretions, secretory IgA (SIgA) plays an important sentinel and protective role in the recognition and clearance of enteric pathogens. In addition to serving as a first line of defense, SIgA and SIgA·antigen immune complexes are selectively transported across Peyer''s patches to underlying dendritic cells in the mucosa-associated lymphoid tissue, contributing to immune surveillance and immunomodulation. To explain the unexpected transport of immune complexes in face of the large excess of free SIgA in secretions, we postulated that SIgA experiences structural modifications upon antigen binding. To address this issue, we associated specific polymeric IgA and SIgA with antigens of various sizes and complexity (protein toxin, virus, bacterium). Compared with free antibody, we found modified sensitivity of the three antigens assayed after exposure to proteases from intestinal washes. Antigen binding further impacted on the immunoreactivity toward polyclonal antisera specific for the heavy and light chains of the antibody, as a function of the antigen size. These conformational changes promoted binding of the SIgA-based immune complex compared with the free antibody to cellular receptors (FcαRI and polymeric immunoglobulin receptor) expressed on the surface of premyelocytic and epithelial cell lines. These data reveal that antigen recognition by SIgA triggers structural changes that confer to the antibody enhanced receptor binding properties. This identifies immune complexes as particular structural entities integrating the presence of bound antigens and adds to the known function of immune exclusion and mucus anchoring by SIgA.     

Impact of Fc N-glycan sialylation on IgG structure

ABSTRACT

Human IgG antibodies containing terminal alpha 2,6-linked sialic acid on their Fc N-glycans have been shown to reduce antibody-dependent cell-mediated cytotoxicity and possess anti-inflammatory properties. Although terminal sialylation on complex N-glycans can happen via either an alpha 2,3-linkage or an alpha 2,6-linkage, sialic acids on human serum IgG Fc are almost exclusively alpha 2,6-linked. Recombinant IgGs expressed in Chinese hamster ovary (CHO) cells, however, have sialic acids through alpha 2,3-linkages because of the lack of the alpha 2,6-sialyltransferase gene. The impact of different sialylation linkages to the structure of IgG has not been determined. In this work, we investigated the impact of different types of sialylation to the conformational stability of IgG through hydrogen/deuterium exchange (HDX) and limited proteolysis experiments. When human-derived and CHO-expressed IgG1 were analyzed by HDX, sialic acid-containing glycans were found to destabilize the CH2 domain in CHO-expressed IgG, but not human-derived IgG. When structural isomers of sialylated glycans were chromatographically resolved and identified in the limited proteolysis experiment, we found that only alpha 2,3-linked sialic acid on the 6-arm (the major sialylated glycans in CHO-expressed IgG1) destabilizes the CH2 domain, presumably because of the steric effect that decreases the glycan-CH2 domain interaction. The alpha 2,6-linked sialic acid on the 3-arm (the major sialylated glycan in human-derived IgG), and the alpha 2,3-linked sialic acid on the 3-arm, do not have this destabilizing effect.     

Assembly, secretion, and vacuolar delivery of a hybrid immunoglobulin in plants

Secretory immunoglobulin (Ig) A is a decameric Ig composed of four alpha-heavy chains, four light chains, a joining (J) chain, and a secretory component (SC). The heavy and light chains form two tetrameric Ig molecules that are joined by the J chain and associate with the SC. Expression of a secretory monoclonal antibody in tobacco (Nicotiana tabacum) has been described: this molecule (secretory IgA/G [SIgA/G]) was modified by having a hybrid heavy chain sequence consisting of IgG gamma-chain domains linked to constant region domains of an IgA alpha-chain. In tobacco, about 70% of the protein assembles to its final, decameric structure. We show here that SIgA/G assembly and secretion are slow, with only approximately 10% of the newly synthesized molecules being secreted after 24 h and the bulk probably remaining in the endoplasmic reticulum. In addition, a proportion of SIgA/G is delivered to the vacuole as at least partially assembled molecules by a process that is blocked by the membrane traffic inhibitor brefeldin A. Neither the SC nor the J chain are responsible for vacuolar delivery, because IgA/G tetramers have the same fate. The parent IgG tetrameric molecule, containing wild-type gamma-heavy chains, is instead secreted rapidly and efficiently. This strongly suggests that intracellular retention and vacuolar delivery of IgA/G is due to the alpha-domains present in the hybrid alpha/gamma-heavy chains and indicates that the plant secretory system may partially deliver to the vacuole recombinant proteins expected to be secreted.     

Regulation of Staphylococcus protease using complement, interferon and immunoglobulin as substrates.

The effects of various agents on the cleavage of serum albumin, interferon, immunoglobulin and complement component C1q by the extracellular protease from Staphylococcus aureus were analysed by SDS-polyacrylamide gel electrophoresis. Arachidonic acid moderately stimulated the proteolysis of serum albumin, interferon and complement component. Phosphatidic acid effectively enhanced the proteolysis of serum albumin and IgG, whereas it inhibited the cleavage of IgM. The proteolysis of IgG was appreciably enhanced by sphingosine. In contrast, phosphatidyl choline and phosphatidyl glycerol were shown to have an inhibitory effect on the proteolysis of IgG and IgM. Phosphatidyl serine, phosphatidyl inositol and phosphatidyl ethanolamine also inhibited the proteolysis of IgG. The failure of any of these agents to exert a persistent effect on the cleavage of all substrates, revealed the complexity of the interactions among the agent, the substrate and the protease.     

Species-specific binding of human secretory component to SpsA protein of Streptococcus pneumoniae via a hexapeptide motif

SpsA, a pneumococcal surface protein belonging to the family of choline-binding proteins, interacts specifically with secretory immunglobulin A (SIgA) via the secretory component (SC). SIgA and free SC from mouse, rat, rabbit and guinea-pig failed to interact with SpsA indicating species-specific binding to human SIgA and SC. SpsA is the only pneumococcal receptor molecule for SIgA and SC as confirmed by complete loss of SIgA and SC binding to a spsA mutant. Analysis of recombinant SpsA fusion proteins showed that the binding domain is located in the N-terminal region of SpsA. By the use of different truncated N-terminal SpsA fusion proteins, the minimum binding domain was shown to be composed of 112 amino acids (residues 172-283). The sequence of this 112-amino-acids domain was used to spot synthesize 34 overlapping peptides, consisting of 15 amino acids each, with an offset of three amino acids on a cellulose membrane. One of the peptides reacted specifically with both SIgA and SC. By using a second membrane with immobilized synthetic peptides of decreasing length containing parts of the identified 15-amino-acid motif a hexapeptide, YRNYPT was identified as the binding motif for SC and SIgA. SpsA proteins with a size smaller than the assay-positive domain of 112 amino acids were able to inhibit the interaction of SIgA and pneumococci provided they contained the binding motif. The results indicated that the hexapeptide YRNYPT located in SpsA of pneumococcal strain type 1 (ATCC 33400) between amino acids 198 and 203 is involved in SIgA and SC binding. Because synthetic peptides containing only parts of the hexapeptide also assayed positive, these results further suggest that at least the amino acids YPT of the identified hexapeptide are critical for binding to SC and SIgA. Amino acid substitutions in the identified putative binding motif abolished SC-/SIgA-binding activity of the mutated SpsA protein, confirming the functional activity of this hexapeptide and the critical role of the amino acids YPT in SC and SIgA binding. Identification of this motif, which is highly conserved in SpsA protein among different serotypes, might contribute towards a new peptide based vaccine strategy.     

Recognition of gram-positive intestinal bacteria by hybridoma- and colostrum-derived secretory immunoglobulin A is mediated by carbohydrates

Humans live in symbiosis with 10(14) commensal bacteria among which >99% resides in their gastrointestinal tract. The molecular bases pertaining to the interaction between mucosal secretory IgA (SIgA) and bacteria residing in the intestine are not known. Previous studies have demonstrated that commensals are naturally coated by SIgA in the gut lumen. Thus, understanding how natural SIgA interacts with commensal bacteria can provide new clues on its multiple functions at mucosal surfaces. Using fluorescently labeled, nonspecific SIgA or secretory component (SC), we visualized by confocal microscopy the interaction with various commensal bacteria, including Lactobacillus, Bifidobacteria, Escherichia coli, and Bacteroides strains. These experiments revealed that the interaction between SIgA and commensal bacteria involves Fab- and Fc-independent structural motifs, featuring SC as a crucial partner. Removal of glycans present on free SC or bound in SIgA resulted in a drastic drop in the interaction with gram-positive bacteria, indicating the essential role of carbohydrates in the process. In contrast, poor binding of gram-positive bacteria by control IgG was observed. The interaction with gram-negative bacteria was preserved whatever the molecular form of protein partner used, suggesting the involvement of different binding motifs. Purified SIgA and SC from either mouse hybridoma cells or human colostrum exhibited identical patterns of recognition for gram-positive bacteria, emphasizing conserved plasticity between species. Thus, sugar-mediated binding of commensals by SIgA highlights the currently underappreciated role of glycans in mediating the interaction between a highly diverse microbiota and the mucosal immune system.     

Secretory glycoproteins of the rat subcommissural organ are N-linked complex-type glycoproteins. Demonstration by combined use of lectins and specific glycosidases, and by the administration of Tunicamycin

Two experimental protocols were used to investigate the secretory glycoproteins of the subcommissural organ (SCO). Protocol I: Lectins, specific exoglycosidases and immunocytochemistry were sequentially applied to the same section or to adjacent semithin sections of the rat SCO fixed in Bouin's fluid and embedded in methacrylate. Lectins used: concanavalin A (con A), wheat germ agglutinin, Limulus polyphemus agglutinin, Ricinus communis agglutinin and Arachis hypogeae agglutinin. Glycosidases used: neuroaminidase, beta-galactosidase, alpha-mannosidase, alpha-glucosidase and beta-N-acetyl-glucosaminidase. For immunocytochemistry an antiserum against bovine Reissner's fiber (AFRU) was used. Lectins and glycosidases were used in sequences that allowed the cleaved sugar residue to be identified as well as that appearing exposed as a terminal residue. This approach led to the following conclusions: (1) the terminal sugar chain of the secreted glycoproteins has the sequence sialic acid-galactose-glucosamine-; (2) the con A-binding material present in the rough endoplasmic reticulum corresponds to mannose; (3) the apical secretory granules and Reissner's fibers displayed a strong con A affinity after removing sialic acid, thus indicating the presence of internal mannosyl residues in the secreted material; (4) after removing most of the sugar moieties the secretory material continued to be strongly immunoreactive with AFRU. Protocol II: Rats were injected into the lateral ventricle with Tunica-mycin and killed 12, 24, 50 and 60 h after the injection. The SCO of rats from the last two groups showed a complete absence of con A binding sites. The results from the two experiments confirm that the secretory glycoproteins of the rat SCO are N-linked complex-type glycoproteins with the conformation previously suggested (Rodríguez et al. 1986).     

Aglycosylantibody. Effects of exoglycosidase treatments on autochthonous antibody survival time in the circulation.

Rabbit anti-hapten antibodies were purified by affinity chromatography and characterized immunochemical for in vivo studies of their blood clearance rate and organ distribution after treatment with various glycosidases. Following sequential removal of sialic acid, galactose, and N-acetylglucosamine with the appropriate cellulose-immobilized exoglycosidases, the antibody populations were recharacterized, radiolabeled, and introduced intravenously into the original animals. Using double radioiodine lables it was possible to demonstrate alterations in purified antibody survival times in the circulation and altered organ distribution after glycolytic cleavage. Removal of terminal sialic acid resulted in rapid blood clearance and enhanced localization of asialoantibody in the liver. Subsequent removal of penultimate galactose residues returned both antibody survival time in the circulation and organ distribution to near normal. Removal of subpenultimate N-acetylglucosamine moieties resulted in aglycosylantibody survival values which were intermediate between asialo- and asialoagalactoantibodies. Removal of the three saccharide also increased kidney localization. The results are evaluated based on current concepts of the biological roles of protein-linked carbohydrate and plasma glycoprotein survival time in the circulation.     

Confocal evaluation of native and induced lectin binding contributes to discriminate between lingual gland glycocomponents in quail

A confocal analysis was performed on the quail (Coturnix coturnix japonica) lingual salivary glands where the carbohydrate chains were studied by lectin histochemistry. For this purpose, appropriate FITC- and TRITC-conjugates were used for double binding also accomplished with sialidase digestion. The glycosidic components of the quail lingual salivary glands were found to be heterogeneously distributed on the different secretory structures as well as on the single secretory elements of each adenomere. The rostral portion of the anterior lingual gland was found to only secrete neutral glycocomponents, characterized by terminal beta-galactose, N-acetylgalactosamine and fucose residues in contrast to the caudal portion that was shown to be extremely heterogeneous and to produce sialylated glycoconjugates characterized by the terminal sequences sialic acid-beta-galactose-N-acetylgalactosamine, sialic acid-beta-galactose-N-acetylglucosamine, and sialic acid-alpha-N-acetylgalactosamine partly codistributed within secretory adenomeres. The posterior lingual gland was observed to be the major contributor to the secretion of salivary mucins containing sialoglycoconjugates with terminal sialic acid residues linked to beta-galactose-N-acetylgalactosamine or alpha-N-acetylgalactosamine often located in distinct secretory elements.     

Microbial interactions in the vaginal ecosystem, with emphasis on the pathogenesis of bacterial vaginosis

During bacterial vaginosis (BV), populations of lactobacilli which are generally dominant in the vagina of overtly healthy women are replaced by other facultative and anaerobic microorganisms. Some Lactobacillus strains produce hydrogen peroxide and all produce lactic acid; however, the antagonistic role of these metabolites in vivo remains controversial. Positive interactions among BV-associated organisms may contribute to the pathogenesis of BV and its sequelae.