Naturally occurring secretory immunoglobulin A antibodies to Streptococcus mutans in human colostrum and saliva

Role of natural salivary defenses in the maintenance of healthy oral microbiota in children and adolescents

Aim

The present study served the purpose of assessing the levels of salivary immunoglobulin A (IgA), immunoglobulin G (IgG), proteins, calcium, inorganic phosphorus, and alkaline phosphatase levels in caries-free and caries active children.

Materials and Methods

Stratified randomized sampling method was used to include 40 subjects in the age group 12-15 years having a full complement of permanent dentition except for third molars. The selected pediatric subjects were further divided into two groups of 20 each based on DMFS score, Group-I - Caries free (DMFS score = 0) and Group-II - Caries active (DMFS score ≥10). Unstimulated midmorning saliva samples were collected and analyzed colorimetrically and by radial immunodiffusion method for constituents of saliva understudy.

Results

The mean salivary IgA levels in children in Group-I (caries-free children) was 10.63 ± 2.85 mg/dL which was statistically higher as compared to caries active children in Group-II (8.50 ± 1.43 mg/dL).The mean salivary protein level in children of Group-II was statistically higher at 3.28 ± 0.12 mg/dL as compared to Group-I (2.89 ± 0.11 mg/dL).

Conclusion

The present study showed decreased levels of salivary immunoglobulin A and high concentration of salivary protein in children with increased caries experience which is indicative of the protective role of salivary constituents in caries-free children.

Breastfeeding and early childhood caries. Review of the literature, recommendations, and prevention

CONTEXT

Early childhood caries is a chronic disease that affects a child's general state of health. The question of a link between primary tooth caries and breastfeeding has been addressed for many years, with contradictory results. The concomitant decay of primary teeth, effective establishment, or not, of oral hygiene, and alimentary diversification away from breastfeeding are all confounding factors in this topic. The aim of our study was to analyze the links between breastfeeding and the appearance of caries, as described in the scientific literature and in the recommendations of specialist societies.

METHODS

A review of publications written in English and French was carried out, searching for the terms early childhood caries, decay and breastfeeding, focusing on literature reviews and meta-analyses dating from the past 10 years. The PubMed database of the US National Library of Medicine National Institutes of Health (NBCI) was used. Furthermore, a review of specialist dental and pediatric societies was conducted.

RESULTS

Breastfeeding until the age of 1 year is not associated with an increased risk of dental caries, and may even provide protection compared with feeding with formula milk. By contrast, infants who are breastfed beyond the age of 12 months demonstrate an increased risk of caries. However, the results derive from heterogeneous studies that do not always take into account contradictory factors such as eating habits of the mother or infant (feeding during the night, number of meals per day, eating sweet foods etc.), dental hygiene, or the sociocultural context. Moreover, the most recent recommendations of pediatric and dental societies advise breastfeeding until the age of 2 years, suggesting that this be accompanied by toothbrushing and better nutrition by reducing the frequency and consumption of sugary foods, aimed at helping parents choose prolonged breastfeeding.

CONCLUSION

Extended breastfeeding is a protective factor for childhood caries under 1 year of age. Beyond 1 year, it is difficult to conclude between protection and aggravation of caries because of the multiplicity of confounding factors such as dietary patterns, which vary depending on countries and families, and problems of oral hygiene. In practical terms, when breastfeeding continues beyond 1 year, consultation with a dentist is necessary for examination and preventive advice regarding dietary practices (especially sugar intake), oral hygiene, or supplementary fluoride.

Cooperativity among secretory IgA, the polymeric immunoglobulin receptor, and the gut microbiota promotes host-microbial mutualism

Secretory IgA (SIgA) antibodies in the intestinal tract form the first line of antigen-specific immune defense, preventing access of pathogens as well as commensal microbes to the body proper. SIgA is transported into external secretions by the polymeric immunoglobulin receptor (pIgR). Evidence is reported here that the gut microbiota regulates production of SIgA and pIgR, which act together to regulate the composition and activity of the microbiota. SIgA in the intestinal mucus layer helps to maintain spatial segregation between the microbiota and the epithelial surface without compromising the metabolic activity of the microbes. Products shed by members of the microbial community promote production of SIgA and pIgR by activating pattern recognition receptors on host epithelial and immune cells. Maternal SIgA in breast milk provides protection to newborn mammals until the developing intestinal immune system begins to produce its own SIgA. Disruption of the SIgA-pIgR-microbial triad can increase the risk of infectious, allergic and inflammatory diseases of the intestine.

Human Male Genital Tract Secretions: Both Mucosal and Systemic Immune Compartments Contribute to the Humoral Immunity

In contrast to numerous studies of female genital tract secretions, the molecular properties of Abs and the magnitude of humoral responses in human male genital tract secretions to naturally occurring Ags and to mucosal and systemic immunizations have not been extensively investigated. Therefore, seminal plasma (SP) collected from healthy individuals was analyzed with respect to Ig levels, their isotypes, molecular forms of IgA, and for the presence of Abs to naturally occurring Ags, or induced by systemic or mucosal immunizations with viral and bacterial vaccines. The results indicated that in SP, IgG and not IgA, is the dominant Ig isotype, and that IgM is present at low levels. IgA is represented by secretory IgA, polymeric IgA, and monomeric IgA. In contrast to the female genital tract secretions in which IgA2 occurs in slight excess, the distribution of IgA subclasses in SP resembles that in plasma with a pronounced preponderance of IgA1. The IgG subclass profiles in SP are also similar to those in serum. Thus, SP is an external secretion that shares common features with both typical external secretions and plasma. Specifically, SP contains naturally occurring secretory IgA Abs to environmental Ags of microbial origin and to an orally administered bacterial vaccine, and plasma-derived IgG Abs to systemically injected vaccines. Therefore, both mucosal and systemic immunization with various types of Ags can induce humoral responses in SP. These findings should be considered in immunization strategies to induce humoral responses against sexually transmitted infections, including HIV-1.

Oral colonization and immune responses to Streptococcus gordonii: Potential use as a vector to induce antibodies against respiratory pathogens

PURPOSE OF REVIEW

Mucosal immunization should be an excellent method of preventing respiratory infections because the local immunoglobulin A antibodies can neutralize the invading pathogens at the site of entry. Because Streptococcus gordonii, a normal inhabitant of the human oral cavity, can naturally elicit a mucosal immune response, it has been a prime candidate for investigations as a live oral vaccine vector for immunization against respiratory infections.

RECENT FINDINGS

Antigens from a number of respiratory bacteria, such as Bordetella pertussis, and one virus have been expressed extracellularly or on the cell surface of S. gordonii. The antigens expressed were single or multiple proteins from one or more pathogens. The recombinant S. gordonii expressing surface-localized heterologous antigens could colonize and persist in the oral cavity of mice and rats. Oral colonization induced a mucosal immunoglobulin A response and, in some instances, also a systemic immunoglobulin G response to the heterologous antigens. When given parenterally, the heterologous antigens generated a systemic immunoglobulin G response. These findings indicate that antigens expressed by S. gordonii are immunogenic. A new approach to the use of S. gordonii as a vaccine vector is to modulate immune responses by co-expressing cytokines with the antigen.

SUMMARY

The ability to express antigens from respiratory pathogens and induce immune responses during oral colonization suggests that S. gordonii may be developed into a live vector for oral immunization against respiratory infections. The major challenge ahead is to find ways to achieve a high level of immune response following oral colonization.

The conjunctival lymphoid follicle in mucosal immunology

The conjunctiva forms a continuous mucosal surface from the eyelid margin to the cornea, and makes contact with airborne antigens and those on the adjacent eyelid skin and preocular tear film. Conjunctival lymphoid follicles (CLF) undergo hyperplasia upon conjunctival infection by a specific array of pathogens; infection-associated enlargement of draining preauricular lymph nodes suggests that CLF participate in the afferent limb of acquired immune responses for the ocular surface. In this review, we examine the evidence for classification of CLF as part of the common mucosal immune system, and explore the possible therapeutic implications.

Detection and rapid increase of salivary antibodies to Staphylococcus lentus, an indigenous bacterium in rabbit saliva, through a single tonsillar application of bacterial cells

In rabbits, Staphylococcus lentus is one of the major bacteria in saliva and a minor bacteria in jejunum fluids and nasal wash. The presence and induction of naturally occurring antibodies reacting to rabbit indigenous bacteria were studied. In non-immune rabbits, the proportion of anti-S. lentus IgA antibodies to total IgA in the saliva was several times higher than that in the intestinal fluids and the nasal wash. The salivary antibodies were found to have increased 1 week after a single tonsillar application of isolated S. lentus cells but not after a single nasal application or a single intragastric instillation. In addition, the anti-S. lentus antibodies in the saliva highly increased with weekly tonsillar applications of isolated S. lentus but increased only one-fifth with weekly nasal applications of the same cells. These results strongly suggest that the palatine tonsils, which we believe had already been sensitized by S. lentus in the physiological condition, induced naturally occurring antibodies in rabbit saliva.

Modified immunogenicity of a mucosally administered antigen

Streptococcus mutans is present in the saliva of most individuals and is modified by salivary components bound to the cells. These saliva-bound S. mutans are swallowed, exposed to high levels of acidity in the stomach, and presented to the common mucosal immune system. Much effort has been directed to identifying the specific S. mutans antigens that the mucosal immune responses are directed against. However, little is known about the host-altered antigenic determinants that the mucosal immune system recognizes. The immunogenicity of gastrically intubated untreated S. mutans cells, cells coated with whole human saliva, cells treated with HCl (pH 2.0), and saliva-coated and acid-treated cells in mice was investigated. Saliva and serum samples were assayed by enzyme linked immunosorbent assay for immunoglobulin A (IgA) and IgG antibodies, respectively, against the untreated or treated S. mutans cells. In general, the levels of salivary IgA and serum IgG antibodies to the antigen against which the mice were immunized were significantly higher (P < or = 0.05). In addition, human saliva and serum samples from 12 subjects were assayed for naturally occurring antibody against the untreated or treated S. mutans cells. In every case, significantly higher reactivity was directed against the saliva-coated and acid-treated cells followed by the saliva-coated S. mutans. These results provide evidence for the altered immunogenicity of swallowed S. mutans in humans by coating native S. mutans antigens with salivary components and/or denaturing surface S. mutans antigens in the acidic environment of the stomach, which would lead to an immune response to modified S. mutans determinants and not to native S. mutans antigens.

Current status of a mucosal vaccine against dental caries

The evidence of a specific bacterial cause of dental caries and of the function of the salivary glands as an effector site of the mucosal immune system has provided a scientific basis for the development of a vaccine against this highly prevalent and costly oral disease. Research efforts towards developing an effective and safe caries vaccine have been facilitated by progress in molecular biology, with the cloning and functional characterization of virulence factors from mutans streptococci, the principal causative agent of dental caries, and advancements in mucosal immunology, including the development of sophisticated antigen delivery systems and adjuvants that stimulate the induction of salivary immunoglobulin A antibody responses. Cell-surface fibrillar proteins, which mediate adherence to the salivary pellicle, and glucosyltransferase enzymes, which synthesize adhesive glucans and allow microbial accumulation, are virulence components of mutans streptococci, and primary candidates for a human caries vaccine. Infants, representing the primary target population for a caries vaccine, become mucosally immunocompetent and secrete salivary immunoglobulin A antibodies during the first weeks after birth, whereas mutans streptococci colonize the tooth surfaces at a discrete time period that extends around 26 months of life. Therefore, immunization when infants are about one year old may establish effective immunity against an ensuing colonization attempts by mutans streptococci. The present review critically evaluates recent progress in this field of dental research and attempts to stress the protective potential as well as limitations of caries immunization.

Mucosal defense of the outer eye

A combination of mechanical, anatomical, immunological, and microbiological factors prevent infection of the outer eye. Mechanical and anatomical factors include the intact epithelium of the conjunctiva and cornea and the constant blinking action of the eyelids. Tear components that play a role in eye defense include lysozyme, immunoglobulins, lactoferrin, and betalysin. The normal bacterial flora of the conjunctiva may also have an inhibitory effect on the survival of more pathogenic species. The eye is linked to the common mucosal immune system, thus gaining the benefits of a system of microbial defense which is primed in the gastrointestinal tract, where a continuing large antigen load is capable of stimulating ongoing immune protection. The relative roles of the various factors contributing to prevention of eye infection remain to be fully defined.

On the rôle of human salivary micelle-like globules in bacterial agglutination

The hypothesis to be tested in this in vitro study was that the salivary micelle-like globules (SMGs) have a rôle in the agglutination of some oral bacteria. An attempt to determine the mechanisms for the interactions involved was also carried out. 4 laboratory and 4 native streptococci strains were tested. Human whole (HWS) and parotid (HPS) saliva was collected from 4 subjects, and SMGs were isolated from both salivas, and agglutination was recorded in the various bacterial suspensions over time. HPS, HWS and SMGs isolated from HPS and HWS caused typical agglutination patterns for the mutans strains. Salivary supernatants (without SMGs) caused a much delayed or no agglutination. Electron microscopy showed SMG-like structures on the surface of the agglutinated bacteria. Addition of pyrophosphate to HPS prevented agglutination, whereas guanidine HCl prevented normal agglutination of a sanguis strain, and urea had no obvious effect. Together, these results indicate that the SMGs are important in the agglutination of streptococci, and that both calcium-dependent, electrostatic and hydrophobic interactions may be involved.

Recognition of immunoglobulin A1 by oral actinomyces and streptococcal lectins

Actinomyces naeslundii and Streptococcus gordonii, oral bacteria that possess Gal/GalNAc- and sialic acid-reactive lectins, respectively, were adherent to immobilized secretory immunoglobulin A (IgA) and two IgA1 myeloma proteins but not to two IgA2 myeloma proteins. Apparently, O-linked oligosaccharides at the hinge region of the IgA1 heavy chain are receptors for lectin-mediated adhesion of these bacteria.

Active release of bound antibody by Streptococcus mutans

Previous studies have shown that Streptococcus mutants is capable of releasing many surface protein antigens, particularly antigen P1. Antigen P1 is immunodominant and has been implicated in adherence of S. mutants to the acquired pellicles. The purpose of this study is to investigate the significance of release of this antigen by the cells. S. mutants NG8 (serotype c) was incubated with an anti-P1 rabbit immunoglobulin G (IgG) or a human colostral IgA which contains natural anti-P1 activity. Results indicated that the bound antibodies were released by the cells in a pH- and time-dependent manner. The optimal pH for release was between 6 and 8, and the release rate reached a plateau in 1 h at 37 degrees C. The release of bound antibodies was considered an active process, since heat-killed cells remained capable of antibody binding but failed to release the antibodies. The release was also dependent on the age of the culture, with early-exponential-phase cells releasing the maximum amount of bound IgG. The released IgG was isolated by polyethylene glycol precipitation and protein A-Sepharose column chromatography and found to be associated with antigen P1, indicating that the antibodies were released together with the antigen in the form of immune complexes. The binding of S. mutans by secretory IgA (SIgA) inhibited the adherence of the cells to salivary agglutinin-coated hydroxylapatite. However, when the SIgA-coated S. mutans was allowed to release the bound antibodies, the inhibitory effect of SIgA on adherence was abrogated. These results suggest that S. mutans is capable of shedding surface-bound antibodies in the form of antibody-antigen immune complexes. Such an action may be a strategy employed by the cells to counter the neutralizing effect of naturally occurring antibodies in the oral cavity.

Intrafamilial similarity in immunoblot profiles of salivary immunoglobulin A antibody activity to oral streptococci

Analysis of the salivary immunoglobulin A (IgA) antibody activity to antigens separated from oral streptococci was carried out on 49 individuals in 11 families. The aim of this study were to i) study the human salivary IgA activity within families to antigens separated from reference strains of Streptococcus mutans, Streptococcus sobrinus and Streptococcus parasanguis and ii) to search for potential differences in the salivary IgA activity to the streptococcal antigens several years apart. The immunoblot revealed similarity in saliva IgA response within the families. A majority of the bands, approximately 7 (median) for each extract was found in both child and parent. A few bands (approximately 3) were found in parents but not in children. Only one to two bands were found in children's saliva without a corresponding band in any of the parents. The antibody activity of saliva samples obtained several years apart was essentially unchanged, especially considering the total number of bands. Differences in the relative intensity of the bands could be seen, and a few bands appeared only in some immunoblots for a specific subject. For 3 of 4 children participating in the longitudinal study, more bands against mutans streptococci appeared with age.

Toxoplasma gondii: detection of antibodies in human saliva and serum

Saliva samples from 27 patients with a recent toxoplasma infection were tested for specific IgG, IgM and IgA antibodies to Toxoplasma gondii. Thirteen of the 27 saliva samples were positive for IgG anti-T. gondii by direct agglutination and 8 of the 27 were positive for IgM anti-T. gondii by an immunosorbent agglutination assay. Twenty of the 27 saliva samples were positive for IgG antibody on toxoplasma immunoblots with three major immunodominant antigens; 38, 30 and 35 kDa. IgA results on toxoplasma immunoblots were positive for all three groups tested, recently infected patients, chronically infected and seronegative adults without distinguishing between them. The 35 and 43 kDa antigens were the most frequently detected proteins. IgM in saliva gave negative or very weak reactions. None of the eight seronegative or the 17 chronically infected adults gave positive results in any of the tests performed to detect IgG or IgM in saliva. Serial saliva and serum samples from a laboratory-infected patient were collected and tested for toxoplasma-specific IgG, IgM and IgA. IgG in saliva was detected by 27 days post infection (p.i.) and was negative by 81 days p.i.; it detected mainly the 38 and 30 kDa antigens. IgM in saliva was detected by 11 days p.i. and was negative by 81 days p.i., with no reaction on immunoblots.

Modulation of herpes simplex virus type 1 replication by human salivary secretions

Saliva functions to protect the oral cavity from pathogenic invasion by modulating the ability of microbes to colonize the oral surfaces or limiting their growth and/or viability. Although the role of salivary secretions in the modulation of the oral bacteria flora has received considerable attention, little is known concerning its role in viral pathogenesis. Accordingly, the purpose of this study was to assess the effect of salivary secretions on herpes simplex virus type 1 (HSV-1) replication. Initially, HSV-1 plaque and titer reduction assays were performed to determine the ability of human submandibular/sublingual (HSMSL) and parotid (HPS) salivas to inhibit the early stages of HSV-1 infection (adsorption and penetration). Our results suggested that both HSMSL and HPS possess cell-protective and virus neutralization activities, with HSMSL being more active than HPS. Additional experiments were performed to determine the effect of saliva on the yield of virus progeny. Again, HSMSL caused a greater reduction of HSV-1 replication than did HPS. A similar effect could not be obtained using vaccinia, suggesting that this inhibitory activity of human saliva is selective. Collectively, these results suggest that human salivary secretions can modulate the replication of HSV-1 in vitro.

Inhibition of Streptococcus mutans adherence to saliva-coated hydroxyapatite by human secretory immunoglobulin A (S-IgA) antibodies to cell surface protein antigen I/II: reversal by IgA1 protease cleavage

The effect of human secretory immunoglobulin A (S-IgA) and serum antibodies to surface protein antigen (Ag) I/II on the adherence of Ag I/II-bearing Streptococcus mutans and of free Ag I/II to saliva-coated hydroxyapatite (SHA) was investigated. The inhibition by S-IgA of binding of both S. mutans and free Ag I/II to SHA was dependent on antibody to Ag I/II. Essentially no difference was found between S-IgA1 and S-IgA2 with respect to antibody-dependent inhibition of Ag I/II binding to SHA, but S-IgA1 inhibited S. mutans adherence more effectively than did either serum immunoglobulin A1 (IgA1) or IgG antibodies. The antiadherence effect of S-IgA was abrogated after cleavage by IgA1 protease. Purified Fab alpha fragments containing Ag I/II-binding activity enhanced the binding of free Ag I/II to SHA and showed greater binding to SHA than did intact S-IgA1. Despite its relative inability to interact with precoated SHA, S-IgA1 containing antibody to Ag I/II was readily incorporated into the salivary pellicle during coating, but this did not promote Ag I/II binding. These data suggest that S-IgA antibodies can inhibit the initial adherence of S. mutans to salivary pellicle-coated tooth surfaces in an adhesin-specific fashion, but the presence in the oral cavity of bacterial IgA1 proteases would potentially interfere with this antiadherence mechanism.

Immunoglobulin-degrading enzymes in localized juvenile periodontitis

Previous reports have indicated the association of periodontal diseases with elevated levels of serum immunoglobulin G (IgG) antibodies to periodontally relevant bacteria. Recent results from this laboratory suggest that enzymes proteolytic for immunoglobulins are important virulence factors of several periodontal bacteria. Specifically, enzymes from Porphyromonas (Bacteroides) gingivalis culture supernatant fluid (SF) cleaved human IgG (4 subclasses), IgA1 and IgA2, IgM, IgD and IgE. Proteolytic enzymes from Actinobacillus actinomycetemcomitans culture SF cleaved IgG, IgA and IgM. An enriched Ig proteolytic preparation from Capnocytophaga ochracea culture SF was shown to extensively cleave all 4 subclasses of human IgG. Extensive degradation of IgG and IgA in crevicular fluid samples on SDS-PAGE from periodontal disease sites of localized juvenile periodontitis (LJP) patients in comparison to little degradation in healthy sites indicated the potential role the proteolytic enzymes from periodontopathogenic bacteria may play in situ. Treatment of IgG with P. gingivalis, A. actinomycetemcomitans and C. ochracea SF resulted in similar patterns of degradation. LJP patients had significantly higher levels of IgG and IgA proteolytic activity in whole saliva than age-, sex-, and race-matched periodontal disease-free controls. However, not all of the proteolytic activity could be ascribed to bacterial proteases since neutrophils are also present in large numbers at diseased sites. Using similar techniques, lysates of neutrophils from healthy controls cleaved IgG, IgA and IgM. The observation of enhanced Ig cleavage activity in crevicular fluid and saliva in LJP patients suggest a role for Ig proteolytic enzymes in LJP.

Natural transmission of Streptococcus sobrinus in rats: saliva and serum antibody responses to colonization

One hundred and twenty weanling rats fed diet NIH 2000 that were free of Streptococcus sobrinus and other mutans streptococci were employed in this study. Sixty rats were inoculated orally with S. sobrinus 6715. Each infected rat (donor) was paired and housed with an uninfected recipient. Saliva and serum samples were collected from 24 (12 donor and 12 recipient) rats at the baseline (day 0) and from groups of 12 recipients sacrificed on days 10, 24, 38, and 52, and the level of infection with S. sobrinus was monitored. Salivary immunoglobulin A (IgA) and IgG and serum IgM and IgG antibodies reactive with whole cells (WC), glucosyltransferase (GTF), and the serotype carbohydrate (g) of S. sobrinus were measured by an indirect enzyme-linked immunosorbent assay. Although the rats were free of S. sobrinus and other mutans streptococci at baseline, they exhibited salivary IgA and serum IgM antibodies reactive with S. sobrinus WC, GTF, and g and serum IgG antibodies reactive with WC and GTF. Infection of recipients with S. sobrinus did not induce salivary antibodies reactive with WC, GTF, or g. In contrast, increases in serum IgM and IgG antibodies reactive with WC and serum IgM antibodies reactive with g were observed.

Ontogeny of immunity to oral microbiota in humans

This article reviews the ontogeny of immune systems in the human oral cavity that may influence the colonization, accumulation, or pathogenesis of oral microbiota. The prenatal development of cellular components associated with the secretory immune system reveals that the initial organization of tissue into Peyer's patches can first be detected immunohistologically at 11 weeks gestation. Epithelial cells positive for secretory component and immunocytes positive for IgM can be detected in salivary gland tissue by 19 to 20 weeks and continue to predominate during gestation. After birth, immunocytes containing IgA begin to dominate. Essentially, no IgA can be detected in saliva at birth. However, salivary IgA and IgM often appear soon thereafter, presumably in response to environmental antigenic and mitogenic challenges. Salivary IgA in young infants has molecular characteristics of secretory IgA and becomes the quantitatively predominate Ig in saliva. Both IgA subclasses are present in proportions characteristic of adult pure glandular salivas in many 1- to 2-month-old infants, although the appearance of IgA2 is delayed in some subjects. Many innate, antibody, and cellular immune components are found in maternal colostrum and breast milk. The antibacterial properties of these maternal factors are diverse and can exert multifaceted protective effects on the infant's alimentary tract. The infant apparently can mount mucosal immune responses quite early in life. For example, salivary antibody activity to organisms that originally colonize the gut (e.g., E. coli) or the oral cavity (e.g., S. mitis, S. salivarius) can be detected by 1 to 2 months of age. Most of this antibody activity has characteristics of secretory IgA, although some IgM antibody can also be initially detected. Salivary IgA1 and IgA2 antibody specificities to S. mitis and S. salivarius components increase qualitatively and quantitatively during the first few years of life. Salivary IgA antibody to components of streptococci that require hard surfaces for colonization (e.g., S. sanguis and mutans streptococci) generally appear after tooth eruption. The loss of placentally derived maternal IgG antibody specificities to these microbiota in the circulation is replaced by de novo synthesis, presumably as a result of the teething process. These IgG antibodies can enter the oral cavity in the gingival crevicular fluid and by the process of teething.(ABSTRACT TRUNCATED AT 400 WORDS)

Function of anti-Streptococcus mutans antibodies: inhibition of virulence factors and enzyme neutralization

The levels of parotid salivary IgA and serum IgG antibodies from dental caries-resistant (CR) and caries-susceptible (CS) individuals to Streptococcus mutans antigens were determined. In general, the levels of salivary IgA and serum IgG antibodies to S. mutans antigens were significantly higher in CR subjects than in CS individuals. There were significantly higher levels of IgA2, but not IgA1, salivary antibodies to S. mutans whole cells in CR subjects than in CS individuals. These results led us to investigate the functional effects parotid saliva and sera containing these antibodies had on several factors associated with S. mutans virulence. Parotid saliva and sera from CR subjects significantly inhibited S. mutans growth, adherence, acid production, glucosyltransferase and glucose-phosphotransferase activities to a greater extent than saliva and sera from CS individuals. The data suggest that neutralization of S. mutans enzymes and inhibition of S. mutans virulence factors by saliva and serum may be responsible for the lower numbers of carious lesions in CR subjects.

Comparison of two assays (EIA and EITB) and two samples (saliva and serum) for the diagnosis of neurocysticercosis

The enzyme immunoassay (EIA), standardized with a crude extract, and the enzyme-linked immunoelectrotransfer blot assay (ETIB) with glycoprotein antigens, were compared by using saliva and serum in the search for specific antibodies against Taenia solium larvae, for the diagnosis of neurocysticercosis. Saliva was slightly more sensitive in EIA (82.1%) than serum (74.1%). In EITB serum was far more sensitive (100%) than saliva (70.4%). The use of EITB with serum is thus an excellent choice for diagnosis of clinical cases of neurocysticercosis, while EIA using saliva represents a useful combination for diagnosis and, especially, epidemiology, because saliva is easily obtained by a painless and non-invasive procedure and the technique is simpler to perform. Furthermore, cross-reactivity of EIA with Echinococcus does not interfere in countries like Mexico where human hydatid disease is not present.

Salivary IgA antibody to oral streptococcal antigens in predentate infants

Salivary IgA antibodies to oral streptococci which colonize the infant oral cavity soon after birth were analyzed in 53 whole salivas of 17 infants who were between three and 27 weeks old. Antibody activities to Streptococcus mitis cells were detected by enzyme linked immunosorbent assay in 78% of the whole salivas by the twelfth week of age. This antibody activity was associated with polymeric IgA as determined after gel filtration of salivas on Superose 6, followed by ELISA. Western blot analyses were used to detect IgA antibodies to Streptococcus mitis and Streptococcus salivarius culture supernatants. Forty one, and 91% of saliva samples contained IgA antibody which reacted in Western blot analyses with S. salivarius and S. mitis culture supernatants, respectively. The youngest infant to show reactive IgA antibody with either oral streptococcal antigen preparation was five week old. Salivary IgA antibody to either bacterial culture supernatant was detected in Western blot only after the isolation of the respective streptococcal species from the oral cavity of these young infants. Some heterogeneity was observed among patterns developed with salivas from different infants. These results suggest that salivary IgA antibody responses may be induced by oral colonization (S. mitis, S. salivarius) by the end of the first month of life.

Avidity of IgA antibody to Escherichia coli polysaccharide and diphtheria toxin in breast milk from Swedish and Pakistani mothers

The avidity of breast milk IgA antibody was studied with the aid of thiocyanate elution of antibody from solid-phase bound E.coli polysaccharides and diphtheria toxoid. The relative avidity index for each sample was determined by the molarity of thiocyanate required to elute 50% of the bound IgA antibody under conditions of antigen excess. Milk samples collected from Pakistani mothers during early lactation (2-4 weeks after delivery; n = 12) had a significantly lower median relative avidity index of IgA antibody to E.coli antigens than did early lactation samples from Swedish mothers (n = 11; avidity indices 1.78 M and 2.65 M; P less than 0.02). Samples collected from Pakistani mothers in mid-lactation showed a significant rise in the relative avidity index to a median of 2.50 M (P less than 0.01), with a subsequent fall in late lactation (28-36 weeks after delivery) to 1.75 M (P less than 0.01). Milk samples from Pakistani mothers in mid-lactation (n = 12) also had a lower median relative avidity index of IgA antibody to diphtheria toxoid than did samples from Swedish mothers (n = 14; avidity indices 2.35 M and 4.30 M; P less than 0.002). The lower avidity of breast milk IgA in Pakistani mothers in comparison with Swedish mothers may arise from differences in antigen exposure or nutritional status or could possibly be genetically determined.

Anti-bacterial IgA and IgG in mouse uterine luminal fluid, vaginal washings and serum

A previous study demonstrated that mouse uterine horns contained bacteria of several species on the morning after mating, and immunolabeling showed that many of these bacteria were coated with immunoglobulins. In the present study we used an ELISA technique to detect naturally-occurring antibodies against bacteria in mouse uterine luminal fluid, vaginal washings and serum. Each fluid contained specific IgA and/or IgG antibodies to five of the six bacterial species recovered from the uterus after mating. The uterine fluid antibodies that bound to the bacteria were mainly IgA molecules, while those in the serum were mainly IgG. Naturally-occurring bacterial antibodies in mouse uterine luminal fluid may play a role in protecting the endometrium against microbial infections.

Antibodies to the oral bacterium Streptococcus mutans and the development of caries in children in relation to maternal dental treatment during pregnancy

These factors were studied in 50 children, aged 3.6 to 5.9 years. Children of mothers who had no dental treatment during pregnancy (NTP-group, n = 25) had significantly (p less than 0.02) more serum IgG antibodies reactive with Strep. mutans than those of mothers who received such treatment (TP-group, n = 25). The children in the NTP-group had fewer Strep. mutans, a higher proportion of intact dentitions, lower dmfs/DS-index and lower caries incidence than those in the TP-group. Over one year of follow-up, a significantly greater proportion of children in the TP- than in the NTP-group developed new caries (p less than 0.05). Thus, maternal dental treatment during pregnancy may affect caries development in the primary dentition of the child, possibly via transplacental immune mechanisms.

Protective secretory immunoglobulin A antibodies in humans following oral immunization with Streptococcus mutans

Ingestion of a vaccine containing killed Streptococcus mutans, originally isolated from each volunteer, daily for 10 consecutive days induced increased levels of specific secretory immunoglobulin A (sIgA) antibodies to S. mutans cells and two cell surface proteins, glucosyltransferase and surface antigen I/II, in parotid saliva and tears of four healthy males and in parotid saliva, tears, colostrum, and milk of a pregnant woman. In addition, these antibodies inhibited glucosyltransferase activity. Both IgA1 and IgA2 antibodies were induced. The levels of IgA antibodies in all secretions remained significantly above preimmunization levels for more than 50 days after oral administration of antigen. A second series of immunizations for 7 consecutive days resulted in even higher levels of sIgA antibodies, which peaked earlier and persisted longer than those observed after the primary immunizations. No increase in levels of antibodies in serum were detected in any subject. Antibodies reactive with human heart and kidney antigens could not be detected in saliva, tears, colostrum, milk, or serum samples collected at any time during the immunization regimen. The numbers of viable S. mutans organisms in dental plaque and whole saliva decreased after each series of immunizations, which correlated with increased levels of IgA antibodies in saliva, suggesting that IgA antibodies in saliva were responsible for the reduced adherence of this bacterium. These results indicate that ingested S. mutans antigen induces secretion of specific IgA1 and IgA2 antibodies in saliva, tears, colostrum, and milk, providing further evidence for the existence of a common mucosal immune system.

The common mucosal immune system and current strategies for induction of immune responses in external secretions

The selective induction of antibodies in external secretions is desirable for the prevention of various systemic as well as predominantly mucosa-restricted infections. An enormous surface area of mucosal membranes is protected primarily by antibodies that belong, in many species, to the IgA isotype. Such antibodies are produced locally by large numbers of IgA-containing plasma cells distributed in subepithelial spaces of mucosal membranes and in the stroma of secretory glands. In humans and in some animal species, plasma-derived IgA antibodies do not enter external secretions in significant quantities and systemically administered preformed IgA antibodies would be of little use for passive immunization. Systemic administration of microbial antigens may boost an effective S-IgA immune response only in a situation whereby an immunized individual had previously encountered the same antigen by the mucosal route. Local injection of antigen in the vicinity of secretory glands is usually accompanied by an undesirable concomitant systemic response and frequently requires the addition of adjuvants that are unacceptable for administration in humans. Immunization routes that involve ingestion or possibly inhalation of antigens lead to the induction of not only local but also generalized immune responses manifested by the parallel appearance of S-Iga antibodies to ingested or inhaled antigens in secretions of glands distant from the site of immunization. Based on extensive studies in animal models as well as in humans, convincing evidence is available that antigen-sensitized and IgA-committed precursors of plasma cells from GALT are disseminated to the gut, other mucosa-associated tissues, and exocrine glands. However, due to the limited absorption of desired antigens from the gut lumen of orally immunized individuals, repeated large doses of antigens are required for an effective S-IgA response. Novel antigen delivery systems for the stimulation of such responses are currently being examined in several laboratories. Live attenuated or genetically manipulated bacteria expressing other microbial antigens have also been used for selective colonization of gut-associated lymphoid tissues. Unique antigen packaging and the use of adjuvants suitable for oral administration hold promise for an efficient antigen delivery to critical tissues in the intestine and deserve extensive exploration. The oral immunization route appears to have many advantages over systemic immunization.(ABSTRACT TRUNCATED AT 400 WORDS)

Differentiation and interaction of secretory immunoglobulin A and a calcium-dependent parotid agglutinin for several bacterial strains

Previous studies have suggested that both secretory immunoglobulin A (sIgA) and various nonimmunoglobulin salivary glycoproteins are capable of agglutinating a variety of bacteria. The present study was designed to compare the nature of the agglutinins for Streptococcus mutans and Salmonella typhimurium in parotid saliva and colostrum. S. mutans was aggregated by saliva and colostrum, whereas S. typhimurium was aggregated only by saliva as detected by a spectrophotometric method. The principal salivary agglutinin for both S. mutans and S. typhimurium was calcium dependent and could be desorbed in phosphate-buffered saline (pH 6.8). In contrast, the colostral agglutinin was calcium independent and not readily desorbed. The agglutinin activities of saliva and colostrum for S. mutans were additive, suggesting independent target sites on the bacterial surface. The agglutinin activity of colostrum was totally associated with sIgA as was suggested by blocking of the agglutinating activity with anti-alpha-chain serum and the absence of blocking with an antibody specific for salivary agglutinin. Interestingly, anti-alpha-chain serum removed all agglutinating activity from saliva, but not from the phosphate-buffered saline-desorbed agglutinin. Dialysis of parotid saliva against 0.1 M disodium EDTA eliminated the agglutinin blocking activity of anti-alpha-chain serum but not that of the antiagglutinin antibody. The ability of anti-alpha-chain serum to block agglutination of the EDTA-dialyzed saliva could be restored by the addition of calcium chloride, suggesting that sIgA and salivary agglutinin are associated through a calcium-mediated interaction. These results indicate that bacterial agglutinating activity of colostrum, as detected spectrophotometrically, is mediated by sIgA, and that of saliva is mainly dependent upon a calcium-dependent nonimmunoglobulin agglutinin. The agglutinating activities of sIgA and parotid agglutinin seem to be additive, and their calcium-dependent association may favor the enhancement of their respective activities.

Antibody response and dental caries in the bacterium Streptococcus-mono-associated, caries-resistant and caries-susceptible rats

Correlations between rat strain, agglutinating antibody responses in serum or saliva and caries incidence, previously observed in Harvard rats mono-associated with Streptococcus faecalis and given diet L128 and 5 per cent sucrose added to drinking water, were not found when experiments were repeated with the low-sucrose diet 305. Mono-association with either Streptococcus mutans 6715 or Strep. faecalis ND547 produced extensive caries in caries-susceptible (HCS) rats and little or no caries in resistant (HCR) ones, but caries incidence did not relate to levels of agglutinating antibodies in serum or saliva. There was markedly less serum antibody to Strep. faecalis in the HCR rats and more antibody in HCS rats, when compared to previous results, but this did not affect caries scores in either strain. No agglutinating antibody to Strep. mutans was detected in serum and indefinite antibody appeared in saliva. Under these conditions, the ability to produce an agglutinating antibody response did not appear to play a role in caries resistance.

The relationship between IgA antibodies to Streptococcus mutans antigens in human saliva and breast milk and the numbers of indigenous oral Streptococcus mutans

The influence of indigenous Streptococcus mutans on naturally-occurring levels of IgA antibodies was studied in 42 lactating females. Breast milk, parotid and whole-saliva samples were collected and analysed by the ELISA method for IgA antibodies, reacting with antigens from Strep. mutans. All salivas and breast milk showed IgA antibody activity to five antigenic preparations from Strep. mutans and to a pool of Escherichia coli antigens. No correlation was observed between the IgA antibody level in breast milk and that in saliva. The total IgA in breast milk was, however, considerably higher than in the salivas. In subjects with active caries and subjects with high DMFS scores, there was a tendency toward lower levels of IgA antibodies in whole saliva than in subjects with low caries experience. The levels of specific IgA antibodies in saliva did not reflect the amount of indigenous Strep. mutans present in the mouth at the time of sampling.

Naturally occurring IgA antibodies to ocular and oral microorganisms in tears saliva and colostrum: evidence for a common mucosal immune system and local immune response

In this study, levels of naturally occurring secretory IgA (sIgA) antibodies to bacterial isolates representative of the microflora of the human eye (Staphylococcus epidermidis and a Corynebacterium species) and the oral cavity (Streptococcus mutans serotypes c and d) were assessed in three different human external secretions. Tears and parotid saliva samples collected at the same time from 22 healthy subjects and colostrum from 11 healthy women (1-14 days post partum) were assessed for sIgA anti-bacterial antibody levels by an enzyme-linked immunosorbent assay. Significantly higher levels (P less than 0.001) of IgA antibodies to Staphylococcus epidermidis and the Corynebacterium sp. were found in tears than in parotid saliva. Furthermore, higher levels of sIgA antibodies to Streptococcus mutans serotype d occurred in parotid saliva than in tears of these subjects. Although levels of salivary sIgA antibodies to S. mutans serotype c were lower than those seen to serotype d, they were not significantly different from those in tears. However, absolute sIgA anti-serotype c antibodies per mg IgA were higher in saliva than in tears. When sIgA antibody levels to the four bacterial strains were assessed in colostrum, the proportion of sIgA antibodies per mg IgA were much lower than seen in tears or saliva. These results suggest that natural sIgA antibodies which occur in human external secretions are induced by antigen ingestion and stimulation of the common mucosal immune system. However, the local presence of antigen at a mucosal site induces greater clonal expression and results in higher levels of sIgA antibodies than at mucosal sites not exposed to local antigenic stimulation.

Duct-associated lymphoid tissue (DALT) of minor salivary glands and mucosal immunity

Minor salivary glands (MSG) play a substantial role in the secretory immunoglobulin A (sIgA)-mediated immunity of the oral cavity. There are two possibilities for the induction of this immunity: (i) an explicitly local antigenic stimulus, or (ii) a remote stimulus as part of the so-called 'common mucosal immune system'. This communication is an attempt to consolidate available evidence in support of both possibilities and to address the former in detail. Although there is strong circumstantial evidence supporting the feasibility of MSG functioning as a part of the common mucosal immune system, direct experimental evidence is yet to emerge. On the other hand, there is increasing structural and physiological evidence in support of MSG serving as a local immunological organ. The purely local response is attributed to the presence of MSG duct-associated lymphoid tissue (DALT), which is comparable to gut- or bronchial-associated lymphoid tissue (GALT or BALT) in origin, tissue organization and function. DALT is accessible to oral antigens by retrograde passage through MSG ducts. Repeated topical antigenic challenging via the oral mucosa may result in the appearance of interacinar plasma cells carrying specific homologous antibodies in MSG. Gut or enteric priming of the same antigen, by passing the oral mucosa by gastric intubation, need not evoke a remote immune response in MSG. Since DALT is more likely to occur in healthy, young growing individuals, who are less likely to undergo bioptic examination of MSG, it has not yet been documented in humans. The physiologically induced DALT is apt to be confused with focal accumulations of lymphoid tissue in pathologically altered MSG, as a consequence of local and some systemic autoimmune diseases. An attempt is made to demarcaate healthy and pathological MSG on the basis of currently available clinical, serological, immunological and genetic evidence.

Immunoglobulin A subclass distribution of naturally occurring salivary antibodies to microbial antigens

The distribution of immunoglobulin A1 (IgA1) and IgA2 antibodies to various microbial antigens was determined in human parotid saliva by using monoclonal antibodies to the IgA subclasses in a solid-phase radioimmunoassay. In 12 subjects examined, antibodies to Streptococcus mutans glucosyl transferase, protein antigen I/II, and cell wall carbohydrate, as well as dextrans B1355 fraction S and B512 and phosphorylcholine, occurred predominantly in the IgA1 subclass. In contrast, antibodies to lipoteichoic acid from Streptococcus pyogenes and whole lipopolysaccharides from Bacteroides gingivalis, Bacteroides fragilis, and Escherichia coli were predominantly of the IgA2 subclass. The data indicate that in most individuals naturally occurring antibodies to a given antigen are predominantly associated with one of the two subclasses of IgA.

Salivary IgA antibody to glucosyltransferase in man

Parotid salivas of 97 young adults were screened for IgA antibody to glucosyltransferase (GTF) from laboratory strains of Streptococcus mutans (serotypes c and g). Antibody levels to GTF from serotype c positively correlated with levels to serotype g GTF among these salivas. GTF's were prepared from S. mutans obtained from a subset of individuals in this population. All but one saliva showed IgA antibody activity to all of the GTF tested. In addition, the relative magnitude of each subject's antibody level was generally the highest to the GTF from their own S. mutans. Fractions, enriched for IgA by ammonium sulphate precipitation and gel filtration, showed patterns of functional inhibition of GTF activity which were consistent with patterns of IgA antibody activity in ELISA of unfractionated salivas. These data indicate that detectable levels of IgA antibody to S. mutans GTF exist in many young adult salivas, while this IgA antibody activity reacts with GTF from different biotypes, subjects generally show the highest secretory IgA antibody levels to their own GTF, and the relative amount of IgA antibody to GTF and the ability to inhibit GTF activity are roughly correlated.

Prevention of Streptococcus mutans colonization by salivary IgA antibodies

The levels of salivary and serum IgA, IgG, and IgM antibodies to the seven serotypes (a-g) of Streptococcus mutans were established in 12 laboratory volunteers using a sensitive enzyme-linked immunosorbent assay. Salivary IgA antibody levels to the serotype c organism were significantly lower (P less than 0.005) than antibody levels to the other six serotypes of S. mutans. Similar results were found with a purified S. mutans serotype c carbohydrate. Serum IgG and IgM antibody titers to the serotype c whole cells were significantly higher (P less than 0.05) than to four other S. mutans serotypes (a, e-g). The abilities of S. mutans serotypes c and d to colonize molar tooth surfaces were examined in eight volunteers. S. mutans serotype d was cleared from the tooth surfaces within 24 hr of challenge, whereas S. mutans serotype c was detected in six of the eight volunteers after 2 weeks and in three of eight after 3 weeks. These results provide additional evidence for the role of salivary IgA antibodies in regulating S. mutans infection and suggest that the low levels of salivary IgA antibodies to S. mutans serotype c may contribute to the predominance of this serotype in the U.S. population.

Serum antibodies against oral Streptococcus mutans in young children in relation to dental caries and maternal close-contacts

Thirty-six children aged 2.6-4.9 years were studied with respect to dental caries, Streptococcus mutans counts in dental plaque, and the estimates of total amount and avidity of serum IgG, IgM and IgA antibodies against Strep. mutans 10449, serotype c. A significant positive correlation (r = 0.49, p less than 0.01) was found between the number of Strep. mutans and caries-index in children. Two children with dental caries had no oral Strep. mutans. In median tests, high antibody titre and avidity of serum IgG antibodies against Strep. mutans were associated (p less than 0.05) with low counts of Strep. mutans. No such relationship was found with IgM or IgA antibodies. Children who had had frequent maternal close-contacts in their first year had significantly more (p less than 0.05) IgG antibodies against Strep. mutans than children with rare close-contacts.

Immunological relationship between anionic antimicrobial proteins from caries-free individuals and known salivary antimicrobial factors

We examined whether the anionic inhibitory proteins identified in mixed saliva from certain caries-free individuals are fragments or degradation products of recognized salivary antimicrobial factors. In the experiments reported here, the anionic inhibitory proteins did not produce precipitin reactions with antisera to any of the established salivary antimicrobial factors examined. Additionally, native, heat-treated, or urea-denatured known salivary antimicrobial factors did not react with the antiserum to the anionic inhibitory proteins. However, the antiserum to the anionic inhibitory proteins was found to be reactive with a protein concentrate from mixed saliva or from separate submandibular and parotid secretions from a number of different donors, as well as with a purified protein fraction containing the homologous anionic inhibitory proteins. These findings suggest that the anionic inhibitory proteins represent intact and unique salivary proteins and not the degradation fragments of salivary antimicrobial protein factors within the oral environment.

Effect of peroral immunization of humans with Streptococcus mutans on induction of salivary and serum antibodies and inhibition of experimental infection

Naturally occurring antibodies reactive with Streptococcus mutans whole cells were assayed in whole saliva, parotid saliva, and blood samples collected from eight human volunteers. The levels and serotypes of indigenous S. mutans in plaque and whole saliva samples were also determined. After baseline sampling the teeth were cleaned and the subjects were inoculated with streptomycin-resistant S. mutans strains Ingbritt (serotype c) and OMZ65 (serotype g). The level of implantation and duration of colonization were determined in plaque and saliva, and antibodies reactive with these strains were monitored in saliva and serum. After the implanted bacteria were shed, the subjects wee immunized by the daily ingestion of an enteric-coated capsule containing 25 mg of Formalin-killed, freeze-dried OMZ65 cells for 3 days and inoculation was repeated. The levels of antibodies and of implantation and the duration of colonization were monitored as before. One month after the bacteria could no longer be detected, the immunization and inoculation cycle was repeated except that the subjects were immunized for 7 days. Five of the eight subjects were successfully colonized by strains Ingbritt and OMZ65. The remaining three did not become colonized with either strain. Strain OMZ65 implanted at a higher level than did strain Ingbritt. Oral immunization did not result in a detectable antibody response in saliva or serum to whole bacterial cells. However, after both the first and second immunizations there were marked reductions in the peak levels of infection and the duration of colonization of both OMZ65 and Ingbritt.

Reaction of human colostral and early milk antibodies with oral streptococci

Colostrum or early breast milk or both from each of 16 healthy women contained agglutinating antibodies for all normal streptococcal inhabitants of the human oral cavity (S. mutans, S. sanguis, S. mitis, and S. salivarius), including those which colonize the neonatal oral cavity in significant numbers. Agglutination correlated with the amount of immunoglobulin A (IgA) binding to bacterial surfaces as measured by mixed reverse passive antiglobulin hemagglutination. Surprisingly, colostral IgA agglutinated our control organism, Brucella abortus. Low levels of colostral or milk IgM and IgG antibodies also reacted with all of the test bacteria. Absorption studies with an enzyme-linked immunosorbent assay showed that a proportion of antibodies in colostrum and early milk is specific for each of the different oral streptococci. Fractionation on Sepharose 4B indicated that 11S secretory IgA is the predominant form of colostral and milk antibody for all of the test bacteria, including B. abortus. No evidence was found that reactions other than antigen-antibody reactions resulted in binding of colostral immunoglobulins by any of the test bacteria.

Natural antibodies in man to Streptococcus mutans: specificity and quantification

Antibodies to whole cells of Streptococcus mutans were examined in 108 subjects by a solid-phase radioimmunoassay and quantified by reference to isotype-specific affinity-purified antibodies. Serum antibodies of each isotype were present in all subjects examined. The mean concentration of serum antibodies to S. mutans was calculated as about 84 micrograms/ml of IgG (range 33-140 micrograms/ml), 26 micrograms/ml of IgA (range 12-43 micrograms/ml) and 9 micrograms/ml of IgM (range 4-15 micrograms/ml). The mean antibody values accounted for about 0.7, 1 and 0.8% of the total IgG, IgA, and IgM, respectively. Overall the antibody binding to whole cells of S. mutans accounted for about 0.8% of the total immunoglobulin. Inhibition experiments using a variety of purified cell wall antigens revealed that the binding of antibodies to whole cells could be inhibited by about 30% with a purified protein antigen (SA I/II) and with glucosyltransferase (GTF), by 25% with c polysaccharide and by 16% with lipoteichoic acid. The protein antigens GTF and SA I/II appear to be major immunogenic cell wall antigens, but natural antibodies in man that bind to S. mutans whole cells have been induced by several antigens, some of which are specific to S. mutans and some of which are shared with other Gram-positive bacteria.

Low secretory IgA concentrations in oral secretions during the acute phase of infectious mononucleosis

Although the Epstein-Barr virus (EBV) relation to infectious mononucleosis (IM) has been well established, the question why IM is not compulsory during a primary EBV infection has yet to be solved. Assuming a possible oropharyngeal secretory immunoincompetence as an etiological component of IM, the secretory IgA concentrations in oral secretions during the acute phase of IM was investigated. Low concentrations of secretory IgA in IM patients (n = 18) were found, mean value 0.180 g/l as compared to those in healthy controls (n = 10), mean value 0.680 g/l. Furthermore, diminishing concentrations of secretory IgA were found during the acute phase of IM. There was no corresponding serum IgA decrease. The investigation also revealed that tinidazole, claimed to be beneficial in the treatment of anginous IM, did not affect the concentrations of spit secretory IgA.

Local immune response to repeated topical antigen application in the simian labial mucosa

Minor salivary glands of the oral mucosa in healthy monkeys (Macaca fascicularis and Macaca mulatta) contain organized structural units suitable for recognizing and processing antigens. A previous study of M. fascicularis monkeys provided experimental evidence of retrograde access of oral antigens deep into the minor salivary glands. The present study aimed at exploring the possible immune response of simian oral mucosa to repeated topical application of a chemically defined antigenic solution at the labial and gut mucosa. Ten female M. fascicularis animals were challenged topically at the lower lip mucosa at weekly intervals for a variable period of 4 to 8 weeks with a solution consisting of horseradish peroxidase, ferritin, and special India ink. Transmission electron microscopic examination of immunohistochemically treated sections of the labial glands revealed the presence of plasma cells containing specific anti-horseradish peroxidase antibody. These cells resided in the interacinar regions. Enteric and gut priming with the same antigen in four other monkeys, bypassing the oral mucosa, failed to reveal the presence of horseradish peroxidase-positive plasma cells in the labial mucosa of any of the four animals, although in one animal such cells could be identified in a mesenteric lymph node. This is suggestive of the existence, at least in primates, of a local immune response of the oral mucosa independent of systemic involvement.