Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Secretory Component”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,099 records · Page 61Linked to original sources
PubMed1986

[Humoral aspects of mucous membrane immunity--perspectives for the female genital tract].

Mucosal immunity of the female genital tract is a part of the "Common mucosal immunity". It is possible to induce local antibodies in the female genital tract by means of oral immunization. From these investigations new perspectives in terms of immunoprophylaxis against bacterial, viral an parasitic infections come into consideration for clinical use. In the case of bacterial infections IgA blocks the attachment of pathogens to relevant mucosal tissues and cells. Predominant among the immune mechanisms is the occurrence of secretory antibodies in the fluids that bath mucosal membranes. Secretory IgA (S-IgA) is an 11S molecule (MW 390,000) consisting of two IgA monomers covalently bonded by joining chain (J chain) and complexed to one molecule of SC.S-IgA ist the main immunoglobulin of mucosal surface. A medically important group of bacterial pathogens produce IgA1 protease cleaving only IgA1 proteins. S-IgA is resistant to protease hydrolysis. The secretory component (SC) is an epithelial cell receptor for the transport of IgA dimers, polymers and IgM polymers. Systemic suppression after oral antigen application has been demonstrated with a variety of thymic-dependent antigens, including heterologous erythrocytes, haptens, and various soluble proteins. Tolerance is mediated by antigen specific T suppressor cells (Ts). Suppressor cells first appear in the gut associated lymphoid tissue and subsequently migrate to systemic sites. At present immunoglobulin estimations in secretions are of clinical importance regarding supporting diagnostic tool of mucosal infections.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody Formation↗
PubMed1976

The SIgA system and hypersensitivity in patients with cystic fibrosis.

A number of investigations have been used for the first time to examine the secretory IgA (SIgA) system in different body fluids from patients with cystic fibrosis (CF). Free J-chain was detected in all the sputum specimens examined. The isolated free secretory component (SC) from CF sputum differed in electrophoretic mobility from the SC isolated from normal human colostrum. In addition the free SC from some CF saliva formed precipitin lines of partial identity with normal human saliva or colostrum. A higher proportion of CF sera (33%) than of normal sera (10%) contained free SC. These investigations suggest that there may be some defect in the synthesis and/or the assembly of the SIgA immunoglobulins, which if confirmed, may help to explain the impaired Type I and Type III allergic manifestations in patients with CF.

Adolescent↗
PubMed1991

Antisperm antibodies in split ejaculates.

The split ejaculation technique concentrates the most motile and viable spermatozoa in the first part of the ejaculate. Several clinicians use this fraction for insemination and in vitro fertilization. Eleven vasovasostomized men with antisperm antibodies participated in this study. The mixed antiglobulin reaction (MAR) for IgG, IgA, and secretory component was carried out on the whole ejaculate and the fractions of the split ejaculate. The isotype and concentration of free antisperm antibodies were determined in serum, the whole ejaculate and the fractions of the split ejaculate by the indirect MAR and the tray agglutination test. The detection of bound antisperm antibodies revealed almost identical reactions in fractions one and two and in the whole ejaculate. The results suggested that the majority of antisperm antibodies in the ejaculate from vasovasostomized men are transuded from serum not only at the epididymal and/or the prostatic level but also in the seminal vesicles.

Adult↗
PubMed1988

An 'antigen capture' ELISA for secretory immunoglobulin A antibodies to hepatitis B surface antigen in human saliva.

An enzyme-linked immunosorbent assay (ELISA) was developed which permits the assay of specific secretory immunoglobulin A (sIgA) antibodies against hepatitis B surface antigen (HBsAg) in saliva. The assay is based on the binding of sIgA antibodies present in saliva to microtitre plates coated with excess of F(ab')2 anti-secretory component antibodies, followed by the addition of specific antigen, HBsAg and finally peroxidase-labelled anti-HBsAg. The assay is fast, simple, reproducible and antigen specific as shown by total absence of inhibition of specific antigen by unrelated antigens but significant inhibition of labelled anti-HBsAg by unlabelled anti-HBsAg. The values obtained for hospital personnel exposed to hepatitis infections (0.068 +/- 0.083 U/ml) and for post-icteric hepatitis B patients (0.062 +/- 0.033 U/ml) were significantly higher than values in control subjects (0.013 +/- 0.006 U/ml).

Adult↗
PubMed1986

Alteration of intracellular synthesis of surface membrane glycoproteins in small intestine of iron-deficient rats.

We studied the activity and kinetic parameters of microvillous enzymes in intestinal villous cells and the concentration of the secretory component (SC) of p-immunoglobulin A in subcellular fractions of crypt cells in 35-day-old rats made iron deficient from birth and in controls. The aim of the study is to investigate the biochemical basis for the decreased activity of brush-border disaccharidases observed in growing animals with chronic iron deficiency. In rats made iron deficient, the specific (per unit protein) and the total (per total intestinal length) activities of sucrase, lactase, maltase, aminopeptidase, and diamine oxidase were decreased from -17 to -66% compared with the activities measured in the controls. The lower activity of sucrase in the brush-border membrane of the iron-deficient rats was associated with much slower enzyme synthesis rate than in control animals. Km of sucrase was identical in both iron-deficient rats and controls, but the maximum velocity of enzyme reaction was reduced proportionally to the enzymatic activity, indicating a lesser amount of enzyme rather than an inactivation. Electron microscopy of epithelial villous cells from iron-deficient rats revealed a marked rarefaction of secretory granules (transport vesicles) without apparent change in the morphology of the brush-border membrane or of cellular organelles. In villus and crypt cells isolated from the jejunum of iron-deficient rats, SC concentration was reduced to a level about half that of the controls. When SC concentration was measured in subcellular fractions of crypt cells, SC content in each fraction was two to three times lower in iron-deprived rats than in controls without evidence of accumulation of the protein at a given subcellular level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Impaired local immune response in vitamin A-deficient rats.

The functional integrity of the local immune system in vitamin A-deficient (A-) rats was investigated. Secretory IgA levels in the intestinal fluid of A- rats were significantly lower than in controls. This and the decrease in intensity of immunofluorescent staining for secretory component (SC) in the intestinal cells was related to the duration of vitamin A deprivation. IgG levels in the intestinal fluid, and serum IgA and IgG levels were unaffected in deficiency. Moreover, when the response of animals to DNP50-BGG was evaluated, the local anti-DNP response in the intestine was markedly depressed. These defects may result from impaired synthesis of SC by epithelial cells. On the other hand, the serum antibody response in deficient animals was not noticeably different from that of the controls; if any, htere was a slight reduction in the affinity of antibody.

Animals↗
PubMed1990

Characterization of an IgA receptor from group B streptococci: specificity for serum IgA.

Some strains of group B streptococci express a cell surface protein which binds IgA. This report describes some properties of such an IgA receptor and compares it with a previously described IgA receptor from group A streptococci. The group B receptor was released in an almost pure form from bacteria incubated at elevated pH, and could be isolated by IgA-Sepharose affinity chromatography. The sequence of the N-terminal 19 amino acid residues was unique. The receptor preferentially binds IgA of human origin, as shown in immunoblotting experiments with purified IgA from nine different species. The affinity constant of the purified receptor for serum IgA was determined to be 3.5 x 10(8) M-1, but for secretory IgA it was too low to allow determination. This result indicates that secretory component and/or J chain interferes with the binding of IgA to this type of bacterial receptor, which may be one of the physiological functions of these polypeptides. A reduction in affinity was also observed for another complexed form of IgA, alpha 1-microglobulin-IgA. The group B receptor is antigenically unrelated to the IgA receptor from group A streptococci (protein Arp), but competitive inhibition experiments indicate that they bind to the same region in IgA. The implications of these findings, and the biological role of bacterial IgA receptors, are discussed.

Amino Acid Sequence↗
PubMed1999

Immunoglobulins of the human amniotic fluid.

PROBLEM: Except for the description of a secretory immunoglobulin (S-Ig) of a low size, no recent study has investigated the molecular status of antibodies in the human amniotic fluid. METHOD: After separation with a high performance chromatography, we analyzed the different isotypes of amniotic Igs by immunoblotting and ELISA. RESULTS: IgG is found to be the major isotype and to contain mother-derived tetanus antitoxins. IgA is much less abundant, whereas no IgM can be detected. IgA is monomeric, with a low level of secretory IgA and with various amounts of free secretory component (SC). The presence of a low level of SC-containing immunoglobulin of a low size is confirmed during the last trimester of pregnancy. This molecule contains no alpha chain but includes a Fabgamma fragment noncovalently associated with SC. IgG, IgA, and SC are detected in the fetal urine and, therefore, can reach the amniotic fluid by this route. CONCLUSION: In addition to the predominant maternal IgG, the amniotic fluid contains different molecular forms of fetal immunoglobulins. Their function as an immune barrier against infection and against mother-derived autoantibodies is discussed.

Amniotic Fluid↗
PubMed1983

[Determination of immunoglobulins A in the fluids of normal human intestinal perfusion].

Immunoglobulin A (IgA) in intestinal secretions is present in several molecular forms among which dimeric IgA linked to the secretory component (S-IgA) predominates. IgA was measured in jejunal perfusates obtained in nine normal subjects by intraluminal perfusion under a proximal occluding balloon of an isotonic and non antigenic solution. The method associated reverse radial immunodiffusion technique or nephelometry, using human serum as standard with chromatography on a polyacrylamide indubiose column. Chromatography separated IgA between two fractions whose elution ratios were the same as those found with mixtures of pure monomeric IgA and S-IgA. A scale was constructed from the latter, allowing the calculation of the percentages of monomeric IgA and S-IgA present in the jejunal perfusates, and that of their total content of IgA.

Chromatography↗
PubMed1999

Could the airway epithelium play an important role in mucosal immunoglobulin A production?

Immunoglobulin (Ig) A is the major immunoglobulin of the healthy respiratory tract and is thought to be the most important immunoglobulin for lung defence. The basis for the preferential generation of IgA-secreting cells in the airway mucosa remains unclear. Given the half-life of 5 days for the majority of IgA plasma cells, many IgA plasma cells must develop daily from B cells to guarantee a continuous supply of IgA antibodies in the airway mucosa. For this, the surrounding cells must provide a constant supply of cytokines necessary for B-cell isotype switch, growth and differentiation into IgA-secreting plasma cells. Studies with CD4+ T-cell knockout mice, T-cell receptor knockout mice and mice made transgenic for CTLA4-Ig demonstrate normal mucosal IgA isotype switch, differentiation and IgA production, thereby suggesting that T cells are not critical for mucosal IgA production, and that other cell sources may be more important. Also, the bronchus-associated lymphoid tissue (BALT), which is believed to be the major site where IgA isotype switch and differentiation of B cells into plasma cells occur with the help of cytokines released by T cells, is not a constitutive feature of the normal human lung. This indicates that other parts of the respiratory tract must carry out the BALT function. We have recently demonstrated that healthy human airway epithelial cells constitutively produce IL-5, a major cytokine implicated in the growth and differentiation of post-switch mIgA+ B cells to IgA-producing plasma cells. Several studies have recently reported that the human airway epithelium also constitutively produces IL-2, TGFbeta, IL-6 and IL-10, factors which are essential for B-cell clonal proliferation, IgA isotype switch and differentiation into IgA-producing plasma cells. The close proximity of B cells to the airway epithelium probably ensures a constant supply of growth and differentiation factors necessary for mucosal IgA production. In addition, the epithelial cells produce a glycoprotein, called the secretory component, which not only confers increased stability to S-IgA, but is also quantitatively the most important receptor of the mucosal immune system, since it is responsible for the external transport of locally produced polymeric IgA and IgM. Recent studies also suggest a possible role for epithelial cells in antigen presentation. Dendritic cells situated within the airway epithelium could directly present antigens to B cells and direct their isotype switch towards IgA1 and IgA2 with the help of cytokines produced by epithelial cells. Airway epithelial cells could therefore play a major role in the production of mucosal IgA antibodies which are essential for airway mucosal defence.

Animals↗
PubMed1981

Secretory IgA estimation in the sera of patients with gynecological cancer.

Secretory component of IgA (SIgA) was isolated by DEAE Sephacel anion exchange chromatography and Sephadex G200, radioiodinated, and a radioimmunoassay procedure developed. The standard inhibition curve was linear to 10 ng/ml. The levels of SIgA in the serum of normal persons was 1.9 +/- 0.1 microgram/ml (mean +/- SE), whereas in lactating women the level was 5.5 +/- 0.5. In cancer of the ovary, endometrium, and cervix, the levels of SIgA were 3.1 +/- 0.3, 2.2 +/- 0.5, and 2.8 +/- 0.4 microgram/ml respectively. A significantly increased level of SIgA was found in 13/24 (54%) of patients with cancer of the ovary and in 5/15 (33%) of patients with cancer of the cervix. Further studies are in progress to establish levels of SIgA following surgery and chemotherapy.

Estrogens↗
PubMed1984

[Secretory immunoglobulin A (S-IgA)/immunoglobulin A (IgA) ratio in cervico-vaginal lavage fluids].

Investigation of the immunoglobulins in the vaginal lavage fluids are semiquantitatively. The aim of the present study was to complete the semiquantitative S-IgA estimations with an "S-IgA/IgA" ratio. An antiserum against the secretory component (Anti-SC) and an S-IgA standard as well as an antiserum against the immunoglobulin A(Anti-IgA) and a serum IgA standard were used. The ratio was proved in vaginal lavage fluids from 5 fertile and 2 infertile women in the course of the menstrual cycle on days 8th, 11th, 14th, 18th and 24th. Progesterone, IgG and IgA were estimated simultaneously in serum samples. According to the "S-IgA/IgA" ratio patients were divided in 2 groups with values higher than 1 on the one side and with values lower than 1 on the other side. In cases with high "S-IgA/IgA" ratio an increased local antibody production and secretion is supposed.

Cervix Uteri↗
PubMed1980

Free sulfhydryl groups of rabbit secretory IgA.

The reaction of sIgA with 5,5'dithiobis (2-nitrobenzoic acid) or with 14C-iodoacetamide revealed an average of 1 mol -SH per mol sIgA under nondenaturing conditions, whereas an average of 7.5 mol -SH was found under denaturing conditions. These -SH groups were found in both the sIgA-f and sIgA-g subclasses; in the sIgA-g subclass, the free -SH groups were found in the Fab alpha portion but not in the Fc alpha portion of the molecule. To determine whether the noncovalently bound polypeptide chains in sIgA contained free -SH groups, sIgA was alkylated with 14C-iodoacetamide and subjected to gel filtration in 6 M guanidine-HCl. This treatment liberated several different polypeptides that were identified as secretory component (SC), L chain dimers, and L chain monomers; measurement of radioactivity incorporated in each of these noncovalently bound chains showed that SC and the L chain dimers did not contain free -SH groups but that an average of 1 -SH group per L chain monomer was found. Of the covalently bound polypeptide chains, J chain and SC did not have detectable -SH groups, whereas the L chains and alpha-chains had 0.3 and 1.2 mol -SH per mol protein, respectively. The identification of free -SH groups in the Fab portion of the sIgA-g subclass and their preferential localization within only some of the L chains reflect the structural heterogeneity of sIgA; these -SH groups presumably arise during biosynthesis.

Animals↗
PubMed1996

Antigen binding properties of purified immunoglobulin A and reconstituted secretory immunoglobulin A antibodies.

The hybridoma cell line ZAC3 expresses Vibrio cholerae lipopolysaccharide (LPS)-specific mouse IgA molecules as a heterogeneous population of monomeric (IgAm), dimeric (IgAd), and polymeric (IgAp) forms. We describe a gentle method combining ultrafiltration, ion-exchange chromatography, and size exclusion chromatography for the simultaneous and qualitative separation of the three molecular forms. Milligram quantities of purified IgA molecules were recovered allowing for direct comparison of the biological properties of the three forms. LPS binding specificity was tested after purification; IgAd and IgAp were found to bind strongly to LPS whereas IgAm did not. Secretory IgA (sIgA) could be reconstituted in vitro by combining recombinant secretory component (rSC) and purified IgAd or IgAp, but not IgAm. Surface plasmon resonance-based binding experiments using LPS monolayers indicated that purified reconstituted sIgA and IgA molecules recognize LPS with identical affinity (KA 1.0 x 10(8)M-1). Thus, this very sensitive assay provides the first evidence that the function of SC in sIgA complex is not to modify the affinity for the antigen. KA falls to 6.6 x 10(5) M-1 when measured by calorimetry using detergent-solubilized LPS and IgA, suggesting that the LPS environment is critical for recognition by the antibody.

Animals↗
PubMed2001

Differential effects of active versus passive coping on secretory immunity.

This study examined the acute immunological effects of two laboratory stressors, expected to evoke distinct patterns of cardiac autonomic activity; namely an "active coping" time-paced memory test, and a "passive coping" stressful video showing surgical operations. We measured salivary S-IgA, IgA-subclasses (IgA1, IgA2), and secretory component (SC). SC is responsible for the transport of S-IgA across the epithelium, and thus a rate-determining step in S-IgA secretion. Thirty-two male undergraduates were subjected to both stressors and a control video (a didactic television program). The memory test induced a typical "fight-flight" response, characterized by increases in heart rate and blood pressure in association with a decrease in cardiac preejection period (PEP) and vagal tone. The surgical video produced a "conservation-withdrawal"-like response, characterized by an enhanced vagal tone, a decrease in heart rate, and a moderate sympathetic coactivation (as indicated by a shortened PEP and an increased systolic pressure). The memory test induced an increase in the concentration and, to a lesser extent, in the output of S-IgA, IgA], and SC. The output of IgA2 was not significantly affected. For the surgical video, a different pattern emerged: During stressor exposure S-IgA remained unaffected, against the background of a small increase in SC output. However, 10 min after the surgical video S-IgA levels had decreased. This decrease in S-IgA was paralleled by a decrease in IgA1, but not IgA2. We conclude that acute stress can have both enhancing and suppressive effects on secretory immunity, the IgA1 subclass in particular. The mechanisms that underlie these divergent responses may include stressor-specific patterns of autonomic activation.

Adaptation, Psychological↗
PubMed2004

Oral manifestations in selective IgA deficiency.

Selective immunoglobulin A (IgA) deficiency is the most common of the primary immunodeficiencies with a frequency of 1/300-1/3000, depending on the screened population. As secretory IgA (SIgA) has a protective role in mucosal surfaces from invasion of microorganisms, it is thought that IgA-deficient subjects are susceptible to periodontal diseases and oral manifestations. Previous studies show contradictory results, concerning the involvement of the individuals' periodontium with IgA deficiency. The aim of this study was to investigate and compare the oral manifestations in IgA-deficient subjects with controls. Eleven selective IgA-deficient subjects aged 3-18 years with serum IgA levels <10 mg dl(-1) and 11 age-sex-matched healthy children as the controls entered the study. Oral mucosal investigation, dental caries, plaque accumulation and periodontal status were assessed. Serum immunoglobulin levels were measured by single radial immunodiffusion (SRID) method. Saliva immunoglobulins and secretory component levels were measured by enzyme linked immunosorbent assay (ELISA) methods. IgA-deficient patients had serum and saliva IgA levels less than 10 mg dl(-1) and 10 microg ml(-1), respectively, but other serum immunoglobulin levels were normal and saliva immunoglobulin M (IgM) levels were increased, compared with controls. There were no significant differences in oral manifestations between IgA-deficient subjects and controls, which may be a result of compensatory increase of saliva IgM or other non-immunological defence factors in saliva. Thus, it is not necessary to evaluate IgA and SIgA in all the patients with oral and dental lesions and it is thought that it is better to investigate other factors.

Adolescent↗
PubMed2004

The influence of prelabor rupture of the membranes on the levels of oral mucosal immunoglobulins in the neonate.

Oral mucosal immunoglobulins play an important role in the human immune system as a first-line defense against viral and bacterial infection. Secretory immunoglobulin A (sIgA), IgD and the free secretory component (FSC) can be determined in the first days of life; however, it is yet unknown which events influence the local synthesis of the immunoglobulins. The aim of this study was to evaluate the influence of prelabor rupture of the membranes (PROM) within a period of 24 h on the synthesis of oral mucosal sIgA, IgD, FSC and albumin of neonates in their first day of life. Comparison of 35 neonates with a history of PROM with a control group of 44 term neonates revealed no significant differences neither with respect to sIgA, IgD, FSC nor to albumin. The results indicate that PROM within a period of 24 h does not significantly increase the synthesis of oral mucosal immunoglobulins in neonates in the first day of life.

Albumins↗
PubMed1986

Secretory antibodies in IgA-deficient and immunosuppressed individuals.

Total levels of IgM and secretory IgM as well as specific antibodies to poliovirus type I antigen, Escherichia coli O antigens, and beta-lactoglobulin were measured in unstimulated and stimulated saliva as well as nasal secretion using an enzyme-linked immunosorbent assay (ELISA). The levels of these antibodies in IgA-deficient adults with and without frequent respiratory infections and children under immunosuppressive therapy for malignant disease were compared to those in normal adults and infants 1-7 months of age. The IgA-deficient adults had significantly higher IgM levels (P less than 0.002) than the normal adults as well as higher levels of IgM antibodies to poliovirus type I (P less than 0.05) and E. coli O antigen (P less than 0.002). There was a less pronounced IgM anti-beta-lactoglobulin compensation. Secretory component (SC)-carrying antibodies against all three antigens were lower than in normal adults. The infants studied had levels of IgM in secretions close to those of the normal adults and significantly lower than those of the IgA-deficient adults (P less than 0.001) but with a higher proportion of SC-carrying IgM. The increase in total IgM and specific bacterial and viral IgM antibodies in saliva above that of the normal adults was significant (P less than 0.001-0.005) for those IgA-deficient individuals without, but not for those with, frequent infections. There was, however, no significant difference between the levels in the two groups of IgA-deficient adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗