sIgA Antibodies Research Articles

Mucosal immunity.

Mucosal defense is provided by a number of host factors countering the specific virulence factors of the many microorganisms infecting the mucous membranes. Secretory IgA antibodies presumably play an important role. Increase of the sIgA antibodies may most advantageously be attained by parenteral immunization, following mucosal priming. This was demonstrated in a rat model, where it was also noted that antigen injection into PP induced high milk IgA antibody levels. In man, parenteral vaccination against polio increased the sIgA antibody levels in the milk of mothers previously exposed naturally to the poliovirus. The response was relatively short-lived. In the previously unexposed, there was little or no response. By contrast peroral immunization with live poliovirus vaccine did not increase, or even decrease, the milk sIgA poliovirus antibody levels. Although salivary sIgA antibodies against antigens of colonizing E. coli appear during the first days of life, they are slow to increase. This deficiency is richly compensated for by all the sIgA antibodies that are provided the baby through the milk. No transfer of dimeric IgA into the milk could be shown in lactating rats, in contrast to what has been reported in mice. There is no evidence for a contribution to milk sIgA from serum in man. Close to parturition, human milk often contains some 7S IgA and various sizes of free SC, in addition to the dominating 11S sIgA. A few days later there is almost exclusively monomeric SC and 11S sIgA. IgG antibodies also play a role at the mucosal level. IgG2 antibodies against the bacterial polysaccharide capsule are as slow to appear as sIgA in ontogeny, possibly explaining the prevalence of infections with encapsulated bacteria and the poor response to polysaccharide vaccines in early childhood. Other defense factors preventing infections by way of mucous membranes may be important. Thus, oligosaccharides present in human milk seem to specifically prevent pneumococcal attachment to retropharyngeal cells. This anti-attachment capacity, in addition to that provided by milk and salivary IgA antibodies, may explain why breast-fed babies have less otitis media than formula-fed ones.

Immunologic factors in human milk during the first year of lactation

The effects of the duration of lactation upon lactoferrin, lysozyme, total IgA, SIgA, SIgA antibodies to Escherichia coli somatic antigens and leukocytes in human milk were investigated. Longitudinal and cross-sectional studies were performed with milk collected from women 20 to 35 years of age during te first year of lactation. Collection and storage conditions and immunologic analyses were controlled to minimize confounding variables. The concentrations of lactoferrin, total IgA, and leukocytes and the uptake of 3H-thymidine by phytohemagglutinin-stimulated lymphocytes fell during the first several weeks of lactation; afterward, the levels of lactoferrin and IgA stabilized. Approximately 90% of total IgA in human milk during the year was SIgA. Secretory IgA antibody titers to E. coli increased in some individuals studied longitudinally suggesting that the enteromammary gland pathway of SIgA antibody production was active after several weeks of lactation. Moreover, the concentrations of lysozyme, after falling to a nadir of 20 to 30 micrograms/ml at 2 to 4 weeks, rose to 200 to 300 micrograms/ml by six months and remained elevated. The immunologic system in human milk undergoes remarkable changes which may represent adaptations for the recipient infant.

S‐IgA CHOLERA TOXIN AND ROTAVIRUS ANTIBODY IN HUMAN COLOSTRUM

S-IgA antibodies against cholera toxin and rotavirus were assayed in 43 colostral samples by means of an enzyme-linked immunosorbent assay (ELISA). All specimens contained specific S-IgA antibodies against both antigens. Significant antibody titres to the antigens were demonstrated in almost all colostral samples.

Effective immunity to dental caries: selective induction of secretory immunity by oral administration of Streptococcus mutans in rodents.

1) The selective induction of secretory antibody is antigen dose dependent. A dose of 10(7) or 10(8) S. mutans CFU (per gram of diet) elicited a significant response, while a higher dose (10(9) CFU/gram) resulted in an apparent state of unresponsiveness. 2) A lowly virulent mutant of S. mutans 6715 (C4) induced protective s-IgA antibodies against challenge with a highly virulent species (C211). Cross protection among serotypes of S. mutans has been achieved. 3) Bovine milk with antibodies to S. mutans significantly reduced the level of caries lesions in rats fed this lyophilized milk and challenged with the homologous, virulent S. mutans strains.

Remote-site stimulation of secretory IgA antibodies following bronchial and gastric stimulation.

The induction of secretory antibodies remains a complex subject with a variety of factors being important: 1) choice of the animal model, 2) the nature of the antigenic stimulus and 3) the method of immunization. Our own investigations have utilized the pregnant rabbit and various DNP-carrier conjugates to probe the manner by which secretory antibodies, particularly secretory (s) IgA, were induced in mammary glands (1–3). These studies demonstrated that: 1) local (intramammary) administration of antigen was effective at reproducibly eliciting s-IgA antibodies (confirming earlier studies (4,5), 2) there was a lack of correlation between the induction of high levels of s-IgA antibodies and serum IgG antibodies, 3) there appeared to be a special relationship between gastrointestinal stimulation and remote-site (mammary) production of s-IgA antibodies, and 4) gastrointestinal stimulation of s-IgA antibodies in milk was not blocked by high levels of circulating IgG serum antibodies. Additional evidence suggested that a similar “remote-site” stimulation phenomenon also existed in other animal species.

Report of the summation committee: recommended areas for future research.

For several years it has been known that mucosal surfaces have common immunologic characteristics. The first such characteristic is that the predominant immunoglobulin is dimeric, US IgA (secretory IgA, s-IgA). It has been shown that large numbers of T-lymphocytes are present on mucosal surfaces and seem to participate in local immune reactions. Despite an awareness that s-IgA provides protection against mucosal viral infections by neutralizing viruses, considerable confusion has existed regarding its protection against bacterial infections. Recent findings have established that s-IgA antibodies in the gastrointestinal and respiratory tracts mediate protection by such mechanisms as limiting adherence of bacteria to epithelial cells, inhibiting bacterial motility, and interfering with the uptake of macromolecular substances from the gastrointestinal tract; other mechanisms for such protection remain to be elucidated.KeywordsMucosal SurfaceMucosal ImmunityLocal Immune ReactionAntigenic DriftMacromolecular SubstanceThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Immunoglobulin A production by human colostral cells: quantitative aspects.

Similar to peripheral blood, human colostrum contains soluble host defense factors and immunologically active leukocytes. While these cells have been characterized with respect to morphology (1), surface markers (2) and some functional aspects (3,4), little is known about their role in the protection of the mammary gland or the recipient infant. Colostral leukocytes consist largely of macrophages and lymphocytes, both thymic dependent (T) and independent (B). However, unlike B lymphocytes from blood, those found in colostrum appear to be programmed toward production of antibodies of the IgA class (4) with specificity for antigens frequently encountered at mucosal surfaces (5). Further indication of the specificity of the antibody from colostral cells was derived from our study of oral immunization of pregnant women with a non-pathogenic strain of Escherichia coli (6). Utilizing a hemolysis-in-gel technique, we demonstrated the rapid appearance in human milk of cells secreting IgA antibody against the 0 antigen of the immunogen. Two further findings of this study provoked the present investigation. First, the appearance of antibody within the colostral leukocytes was not consistently accompanied by a rise in the level of secretory IgA (s-IgA) antibodies in colostral whey (5,6).KeywordsTotal CultureHuman ColostrumPlastic Microtiter PlateSecretory ImmunityLocal Lymphoid TissueThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Effect of Cow's Milk on the Gastrointestinal Tract: A Persistent Dilemma for the Pediatrician

The confusing area of cow's milk intolerance is explored in an attempt to define the various mechanisms whereby milk affects gastrointestinal function, resulting in clinical symptoms (diarrhea, vomiting, gastrointestinal bleeding, etc.). The adverse reaction of infants to cow's milk ingestion may relate to lactose intolerance (enzymatic), a direct toxic reaction to the mucosal surface resulting in epithelial damage, or it may be immunologically mediated. Factors such as increased intestinal permeability to milk proteins during the newborn period may also contribute to susceptibility of young infants to milk sensitivity. The relative roles of systemic (milk agglutinins) and local immunity (SIgA antibodies) in milk intolerance are discussed and differential immunologic responses (IgE versus IgA/IgM) considered in the pathogenesis. It was concluded that new techniques such as organ culture of intestinal biopsy specimens are needed to establish the diagnosis of hypersensitivity and to begin to provide ways of adequately treating the condition.

The secretory immunoglobulin A response in the gut [proceedings

s of Communications Meeting of the Biochemical Society lmmunoglobulin Discussion Group and the British Society for Immunology held at the University of Bristol, I April 1977 IMMUNOGLOBULIN A AND MUCOSAL PROTECTION : a Colloquium organized by J. R. Clamp (Bristol) The Secretory Immunoglobulin A Response in the Gut JOHN J. CEBRA, PATRICIA J. GEARHART, RAMESH KAMAT, STELLA M. ROBERTSON and JEENAN TSENG Department of Biology, The Johns Hopkins University, Baltimore M D 2121 8 , U S A . Humoral immunity manifest in the mammalian gut is often due to the presence there of sIgA (secretory immunoglobulin A) antibodies. A considerable proportion of antibodies of this immunoglobulin isotype are synthesized locally by plasma cells, which are abundant in intestinal lamina propria. B-lymphocyte precursors for IgAsecreting plasma cells (‘IgA plasma cells’) appear to derive from the Peyer’s patches (aggregated lymphatic follicles) of the small intestine. The Peyer’s patches of rabbits contain a subpopulation of B-lymphocytes that can repopulate the spleen and lamina propria of irradiated allogeneic recipients with IgA plasma cells (Craig & Cebra, 1971). Pokeweed mitogen stimulates this subpopulation in vitro to generate IgA plasma cells (Jones et al., 1974). The immediate precursors for IgA plasma cells have been isolated in the subpopulation of Peyer’s-patch cells bearing membrane Fab, and lacking membrane IgM by fluorescence-activated cell-sorting (Jones et al., 1974; Jones & Cebra, 1974). In addition to supplying precursors for IgA plasma cells, an ‘antigen-sampling’ role has been ascribed to Peyer’s patches (Bockman & Cooper, 1973). Whole protein molecules may pass intact across their specialized dome epithelial cells and arrive in the midst of B-lymphocyte follicles. Thus IgA precursors may have their first encounter with antigen in the Peyer’s patches, be stimulated to divide, and migrate in lymph/blood to intestinal lamina propria and generate plasma cells. We have devised an adoptive transfer system to compare the antigen-sensitivity of Peyer’s-patch cells with cells from peripheral lymph nodes and spleen (Cebra et al., 1977a,b). Syngeneic or congeneic (CB20+Balb/c) cells were transferred into sublethally irradiated (600rad) recipients which were then challenged 1 day later with 5 x lo8 sheep erythrocytes. Antibody-forming cells in the recipients’ spleens were enumerated at various times thereafter by the Jerne plaque assay and by facilitating antisera to distinguish cells making IgM, IgGl, IgG2 and IgA isotopes. Fluorochrome-labelled alloantisera, which distinguished IgA from CB20 (Ig-2*) and Balb/c (Ig-2“) congeneic mice, were used to determine the origin of IgA plasma cells in recipient mice. The Peyer’s-patch cells were as effective in adoptively transferring IgM and IgG responses as cells from peripheral lymph nodes or spleen. However, only Peyer’s-patch cells transferred a significant IgA response, which began at about day 10 after transfer and reached a maximum of IgA

Esch. coli infections in childhood. Significance of bacterial virulence and immune defence.

The Esch. coli harboured in the gut constitute a reservoir of potential pathogens in the infant and child. The conditions required for these intestinal inhabitants to cause infection are not well understood. The presence of virulence factors such as capsular antigens, especially K1, may be of significance for the ability of Esch. coli to cause neonatal meningitis. The capacity of certain Esch. coli to attach to epithelial cells of mucous membranes may be important for their infective powers in the urinary as well as the intestinal tract. Furthermore, the ability of certain Esch. coli to produce enterotoxins similar to that of V. cholerae is of importance for their capacity to provoke diarrhoea. The importance of the immune defence mechanisms for prevention of these Esch. coli infections is suggested, especially in the form of local immunity provided by secretory IgA antibodies. Such antibodies directed against Esch. coli O and K antigens as well as enterotoxins are present in large amounts in human milk and may be of considerable importance for protection against Esch. coli in the breast-fed baby. Breast feeding may be of special significance until the baby has built up its own local immune defence preventing the micro-organisms from attaching to and invading the intestinal mucous membranes. SIgA antibodies in urine may have a similar protective effect against urinary tract infections. The variable pictures of Esch. coli infections in childhood are striking, ranging from severe sepsis/meningitis or diarrhoea to "asymptomatic" bacteriuria. This variability is obviously closely connected with the presence of various virulence factors and the function of different components of the immune defence.

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

Human colostrum, parotid saliva, and serum were assayed for the presence of naturally occurring antibodies to five serotypes of Streptococcus mutans. Appreciable levels of agglutinins to strains AHT, BHT, 10449, 6715, and LM-7 (groups a leads to e, respectively) were detected in normal colostrum and saliva, whereas relatively low levels were found in serum. No agglutinins could be detected in the colostrum or saliva of immunodeficient patients. Molecular sieve chromatography of the colostrum on Sephadex G-200 revealed agglutinin activity in the secretory immunoglobulin A (s-IgA)-rich fraction only. Titration of purified colostral s-IgA confirmed the IgA nature of this agglutinating activity. Indirect immunofluorescence tests with anti-s-IgA, -IgG, and -IgM revealed S. mutans specificity only in the s-IgA class. The presence of s-IgA antibodies to indigenous oral microorganisms in colostrum, as well as in saliva, suggests that antigenic stimulation occurs at a site remote from the oral mucosa.

Specificity of opsonic antibodies to enhance phagocytosis of Pseudomonas aeruginosa by human alveolar macrophages.

These studies compared the ability of specific secretory IgA (sIgA) and IgG antibodies to promote phagocytosis of viable pseudomonas aeruginosa by human alveolar macrophages. Macrophages were obtained by lung lavage of normal adult smoker and nonsmoker volunteers and were maintained as in vitro cell monolayers. Both immune sIgA and IgG agglutinating antibodies were demonstrated to coat and opsonize viable bacteria, whereas similar nonimmune immunoglobulin preparations did not. When alveolar macrophages were challenged with viable opsonized 14C-labeled Pseudomonas IgG-reacted bacteria were ingested better and killed more readily than sIgA-opsonized organisms. Phagocytic responses were not significantly different between macrophages obtained from smokers and nonsmokers. Although sIgA and IgG antibodies can be found in respiratory secretions and both are undoubtedly important in pulmonary host defense, IgG opsonic antibody was superior in enhancing the uptake of Pseudomonas by in vitro-cultured alveolar macrophages. It may be the more important respiratory antibody for certain bacterial infections.

On the physical-chemical effect of colostral antibody binding to Escherichia coli O 86.

Sensitization of Escherichia coli O 86 with colostrum or purified colostral sIgA antibody produces a physical-chemical change of the bacterial surface detectable as a change in partition in dextran-polyethylene glycol polymer two-phase systems. Sensitization with colostrum or sIgA reduces affinity for the dextran-rich phase. In contrast immune serum, IgG and complement increase the affinity for that phase. The results are compatible with the hypothesis that hydrophilic particles, e.g. certain strains of bacteria, are less liable to attachment to and phagocytosis by animal cells than hydrophobic particles, e.g. other bacterial strains. Sensitization with secretory IgA enhances the hydrophilicity thereby making possible an escape mechanism operating at the mucosal surfaces.

Antifertility effects of immunoglobulins from uterine fluids of semen-immunized rabbits.

The effects on fertility of the immunoglobulins, IgG (similar to serum IgG) and secretoy IgA (the predominant IgA in uterine fluid, different from serum IgA) and the fluids from the uteri of semen-immunized rabbits were studied. Female rabbits were immunized either by transvaginal (TV) injections (every 4 or 5 days for 3 weeks) with adjusted semen added to buffered saline containing .5 mg each polyadenylic acid )Poly-A) and polyuridylic acid or a combination of transvaginal injections and systemic injections with rabbit semen mixed with adjuvant (each once weekly for 3 weeks). 2 weeks following the last injection of semen each rabbit received a TV injection followed in 1 week by an instillation of semen and Poly A and U into uterine horns ligated at both ends. 2 weeks following intrauterine (IU) instillation uterine contents were withdrawn. Uteri were reinstilled. Passive hemagglutinating (PHA) and sperm-immobilizing antibody titers were determined on both serum and adjusted uterine fluid (UF) samples. Sperm immobilizin tests and PHA were positive in all serum samples from the contained immunization group, and PHA were positive in 4 out of 7 UF samples of this group. 2 out of 10 and 3 out of 10 samples from the TV group were positive for SI and PHA, respectively, and 4 out of 10 UF samples were PHA positive. Treatment of rabbit semen with UF samples prior to insemination of estrous rabbits resulted in an implantation rate of 2.8% for the combined immunization group and 24.2% for the TV group compared to 79.2% for controls. Some IUF samples without detectable antibodies appeared to inhibit fertility. The implantation rate of sperm treated with immune UF from the TV group absorbed with goat normal serum, anti-rabbit gamma-globulin serum, anti-rabbit-secretory IgA serum, anti-rabbit IgG serum, or sperm, were 3.4%, 88.9%, 42.9%, 64%, and 73. 3% respectively. SIgA and IgG antibodies were seperated by gel filtration. 2 of 4 pooled IgA samples and 3 of 4 pooled IgG samples depressed fertility, with 24.3% and 22.6% implantation and 25.8% 5, and 0% implantation, respectively. To assure that the antifertility effects observed were due to sperm antibodies of each immunoglobin class, SIgA fractions of 2 IUF pools were subjected to anion-exchange chromatography, and both SIgA and IgG fraction were absorbed with goat NS, anti-SIgA, and anti-IgG. IgG fractions absorbed with anti-SIgA or anti-IgG resulted in implantation rates of 0% and 56.8%, respectively, compared to a control of 89.5%. SIgA fractions absorbed with anti-SIgA or anti-IgG resulted in implantation rates of 81.8% and 19.4%. Thus IgG and secretory IgA of the uterine fluids are active in inhibition of fertility.

The IgA antibody-forming cell response in the rabbit submandibular gland following several different methods of immunization.

Secretory IgA (sIgA) is found in the saliva of humans and other animals where its principle sources are the major salivary glands. Taubman and Smith (1) showed that salivary IgA antibody, induced by vaccination with cariogenic S. mutans, was correlated with a decrease in dental caries in rats. The practical use of the secretory immune system in protection against disease in humans depends partly on a clear understanding of the mechanisms which govern the induction of a secretory immune response. There are numerous reports showing that topical application of antigen to the gastrointestinal or respiratory tracts can result in induction of sIgA antibodies (cf. reviews 11,12). It is not clear however, how best to induce sIgA antibody production in solid organs such as the salivary and lacrimal glands. In this study we systematically examined several methods of immunization designed to stimulate a secretory immune response in the salivary glands of rabbits.