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 361 records · Page 20Linked to original sources
PubMed1986

[Immunohistochemical localization of secretory component and IgA in the normal and cancerous endometrium].

Using normal and cancerous endometrial tissues obtained from climacteric and postmenopausal women as the subjects, localizations of secretory component (SC) and IgA were immunohistochemically investigated. The results were as follows: Similar to cyclic women, in normal endometrial tissues from climacteric and postmenopausal women, SC and IgA localized mainly in glandular epithelia. However, in women over 60 years of age, immunoreactivity of SC and IgA decreased. In cancerous tissues, staining intensity of SC and IgA decreased clearly as compared to normal tissues. Also, the loss of polarity was recognized in the localization pattern of SC and IgA. In relation to the tissue differentiation, a further decline was recognized in the SC and IgA staining intensity in the poorly differentiated carcinoma as compared to the well differentiated type. The above findings suggested that the decline of the local immune system in the endometrium, namely, weakening of the local defense mechanism against infections, took place in women of advanced age. Also it was recognized that weakening of the ability to produce SC was caused by the malignant transformation of endometrium, and it was suggested that SC was a substance which had a close relationship to tissue differentiation.

Adult↗
PubMed1999

Mapping the interaction between murine IgA and murine secretory component carrying epitope substitutions reveals a role of domains II and III in covalent binding to IgA.

We have identified sites for epitope insertion in the murine secretory component (SC) by replacing individual surface-exposed loops in domains I, II, and III with the FLAG sequence (Crottet, P., Peitsch, M. C., Servis, C., and Corthésy, B. (1999) J. Biol. Chem. 274, 31445-31455). We had previously shown that epitope-carrying SC reassociated with dimeric IgA (IgA(d)) can serve as a mucosal delivery vehicle. When analyzing the capacity of SC mutants to associate with IgA(d), we found that all domain II and III mutants bound specifically with immobilized IgA(d), and their affinity for IgA(d) was comparable to that of the wild type protein (IC(50) approximately 1 nM). We conclude that domains II and III in SC are permissive to local mutation and represent convenient sites to antigenize the SC molecule. No mutant bound to monomeric IgA. SC mutants exposing the FLAG at their surface maintained this property once bound to IgA(d), thereby defining regions not required for high affinity binding to IgA(d). Association of IgA(d) with SC mutants carrying a buried FLAG did not expose de novo the epitope, consistent with limited, local changes in the SC structure upon binding. Only wild type and two mutant SCs bound covalently to IgA(d), thus implicating domains II and III in the correct positioning of the reactive cysteine in SC. This establishes that the integrity of murine SC domains II and III is not essential to preserve specific IgA(d) binding but is necessary for covalency to take place. Finally, SC mutants existing in the monomeric and dimeric forms exhibited the same IgA(d) binding capacity as monomeric wild type SC known to bind with a 1:1 stoichiometry.

Animals↗
PubMed1999

Recombinant expression of polymeric IgA: incorporation of J chain and secretory component of human origin.

Mucosal J (joining) chain-expressing IgA immunocytes produce dimeric IgA that is actively transported by the epithelial polymeric Ig receptor (pIgR) to exocrine secretions. Release of secretory IgA (SIgA) occurs by cleavage of the covalently linked pIgR ectodomain, also known as bound secretory component. We have identified the human J-chain cDNA sequence through database screening, and isolated it from B cells for recombinant expression. Co-expression of this cDNA with an alpha heavy chain and a lambda light chain in Chinese hamster ovary (CHO) cells resulted in a mixture of recombinant monomeric and dimeric IgA in culture supernatants. This dimeric IgA was transported by the pIgR-mediated mechanism in vitro. Furthermore, expression of the human pIgR ectodomain together with the dimeric IgA, resulted in production of complete SIgA by the CHO cells. These results demonstrated that co-expression of the necessary polypeptide components allows a single mammalian cell to produce SIgA. Development of production systems for human antigen-specific recombinant SIgA may be important for applications in passive mucosal vaccination.

Amino Acid Sequence↗
PubMed1977

Immunoglobulin M associated with secretory component and immunoglobulin A deficiency in bovine colostrum.

Immunoglobulin (Ig) M purified from bovine colostrum was examined by an immunodiffusion analysis with antisecretory IgA serum and was found to be associated with a secretory component. Some of the combined proteins were dissociated if treated with 5 M guanidine-HCl and others were not. Another immunodiffusion analysis of 23 specimens of colostrum led to the finding that certain colostrums were deficient in IgA, even though they contained IgG and IgM.

Animals↗
PubMed1986

A bovine epithelial membrane protein that binds polymeric immunoglobulin and has a structure related to that of bovine secretory component.

A protein of Mr 94000 was isolated from detergent-solubilized bovine intestinal, liver and mammary-gland membranes. It binds immunoglobulin M and also undergoes proteolytic fragmentation in a similar manner to bovine secretory component (Mr 74000). The affinity-purified membrane protein is therefore most likely to be the bovine epithelial receptor for polymeric immunoglobulin. A structural model is proposed.

Animals↗
PubMed1979

Serum proteins and secretory component in human carious dentin.

By the use of the peroxidase-labeled antibody method, significant localization of IgG, IgA, albumin and transferrin was demonstrated in the deep lesion of 20 carious teeth, where the secretory component was absent. These serum proteins formed a distinct zone, surrounding the overlying, shallow lesion infected with bacteria.

Adolescent↗
PubMed1993

Ultrastructural and antigenic preservation of a delicate structure by cryopreparation: identification and immunogold localization during biogenesis of a secretory component (membrane-matrix connection) in Paramecium trichocysts.

Ultrastructure and antigenicity of the "mesh-like sheath" (MLS), a very delicate structure connecting the membrane and the paracrystalline matrix of Paramecium trichocysts, are well preserved after cryofixation (rapid freezing followed by freeze-substitution in methanol and embedding in Lowicryl K11M at 213K). The MLS is labeled by colloidal gold-bound antibodies (Ab-Au10nm) with primary antibody (Ab) against trichocyst components obtained by recloning hybridoma cells twice. We prepared Western blots from reduced gels obtained from subfractionated trichocysts. Trichocyst membranes displayed reactive bands of 68-70, 63-66, 43, 40 (strongest), and 57 and 54 KD, with a weak band of 38 KD. One of the most abundant protein bands of soluble secretory components (56-57 KD) was also strongly stained on blots. On ultra-thin sections pre-trichocysts display Ab-reactive material concentrated below the trichocyst membrane before the MLS can be recognized as a structural entity. Quantitative evaluation of Ab-Au10-labeled ultrathin sections also revealed passage of MLS materials through the very inconspicuous Golgi apparatus. This was substantiated by Ab-peroxidase labeling. We conclude that MLS components (whose ultrastructure is difficult to preserve) are largely membrane-associated, partly soluble proteins. They form a connection (released during exocytosis) between the abundant paracrystalline matrix components and the organelle membrane. MLS might thus maintain a peripheral aqueous space of functional importance.

Animals↗
PubMed1994

Purified excretory-secretory component of filarial parasite enhances Fc epsilon RII/CD23 expression on human splenic B and T cells and IgE synthesis while potentiating T-helper type 2-related cytokine generation from T cells.

The CD23-bearing cells are known to be involved in multiple biological activities, including IgE synthesis and IgE-dependent cytotoxicity to parasites. The factors that regulate interleukin-4 (IL-4)-induced IgE synthesis in helminthic infection were analysed by using an excretory-secretory component (ESC) of Dirofilaria immitis (DI). Human splenic B and T cells significantly enhanced the expression of low-affinity Fc receptors for IgE (Fc epsilon RII/CD23) by stimulation with ESC, either acting alone or in synergy with IL-4. On B cells, ESC potentiated the CD23 expression in synergy with IL-4, whereas ESC alone was unable to modulate CD23 expression. In contrast, ESC directly induced CD23 expression on T cells by acting alone and no further enhancement was observed in the presence of IL-4. Furthermore, IL-4-induced IgE synthesis by splenic mononuclear cells (SMNC) was greatly enhanced in the presence of ESC. Of particular interest, T cells primed by ESC significantly produced a set of cytokines including IL-3, IL-4, IL-5 and IL-6. Inasmuch, IL-4-induced IgE synthesis in helminthic infection may be selectively modulated by parasite protein(s) acting on the generation of T-helper type 2 (Th2)-related cytokines.

Animals↗
PubMed1979

The secretory component of the interdigestive migrating motor complex in man.

Intraduodenal pH, bicarbonate and amylase secretion, and gastric acid and pepsin output were studied in relation to the migrating motor complex in man. The occurrence of a motor complex in the duodenum was preceded by an increase in gastric acid and pepsin output and followed by a peak in bicarbonate and amylase secretion. It is concluded that the interdigestive phase in man is characterized by periodic activity complexes comprising both motor and secretory components. These observations may have important implications for the interpretation of currently used functional tests of gastrointestinal secretion.

Amylases↗
PubMed2001

Androgen-receptor-specific DNA binding to an element in the first exon of the human secretory component gene.

Androgens and glucocorticoids are steroid hormones, which exert their effects in vivo by binding and activating their cognate receptors. These intracellular receptors are transcription factors that can bind specific DNA sequences, called hormone response elements, located near the target genes. Although the androgen receptor (AR) and the glucocorticoid receptor (GR) bind the same consensus DNA sequence, androgen-specific responses can be achieved by non-conventional androgen response elements (AREs). Here we determine the specificity mechanism of such a selective element recently identified in the first exon of the human gene for secretory component (sc ARE). This sc ARE consists of two receptor-binding hexamers separated by three nucleotides. The DNA-binding domains of the AR and GR both bind the sc ARE, but, although the AR fragment dimerizes on the element, the GR fragment does not. Comparing the affinities of the DNA-binding domains for mutant forms of the sc ARE revealed that dimeric GR binding is actively excluded by the left hexamer and more precisely by the presence of a G residue at position -3, relative to the central spacer nucleotide. Inserting a G at this position changed a non-selective element into an androgen-selective one. We postulate that the AR recognizes the sc ARE as a direct repeat of two 5'-TGTTCT-3'-like core sequences instead of the classical inverted repeat. Direct repeat binding is not possible for the GR, thus explaining the selectivity of the sc ARE. This alternative dimerization by the AR on the sc ARE is also indicated by the DNA-binding characteristics of receptor fragments in which the dimerization interfaces were swapped. In addition, the flanking and spacer sequences seem to affect the functionality of the sc ARE.

Animals↗
PubMed1991

Secretory component of cystic craniopharyngiomas: a mucino-histochemical and electron-microscopic study.

Ten cases with cystic craniopharyngioma were investigated. Histologically, eight of them belonged to the adamantinomatous group and two were squamous epithelial type. Histochemical investigation revealed mucin secretion in microcysts, and electron microscopy demonstrated zymogen granules in the epithelial cells. When the protein content of the cyst fluid was analyzed by polyacrylamide-gel electrophoresis, the electrophoretic pattern and immunological properties were found to be similar to the normal human serum control. The results of the morphological study suggest that cystic craniopharyngiomas have a secretory component in addition to the classical histological structures.

Ameloblastoma↗
PubMed2002

Secretory component, J chain, and immunoglobulins in human embryos and fetuses of the first trimester of pregnancy: immunohistochemical study.

In our previous studies, we described the development of the secretory (mucosal) immune system (SIS) in human fetuses in the second trimester of pregnancy. In the present study, we examined the presence and distribution of components of this system in human embryos and early fetuses in the first trimester. An immunohistochemical study was performed on 17 embryos and 9 fetuses (4 to 12 wk of development) using antibodies against secretory component (SC), joining (J) chain, immunoglobulins (IgA, IgM, IgG), subsets of T and B lymphocytes, and macrophages. Cells positive for SC, J chain, and IgG were found in epithelial tissues from wk 4 of pregnancy. In the internal organs, such as the myocardium and endocardium, capillary endothelium, epithelium of the kidney tubules and some others, only J chain and immunoglobulins were seen. IgA was weakly reactive in tissues where SC and/or J chain were presented. IgM was very weak or absent. Among the cellular components of the SIS, only macrophages were seen in 4-wk-old embryos. CD3+ and CD20+ lymphocytes were found at wk 7 to 8. IgA- and IgM-positive lymphocytes appeared at the end of wk 9. The SIS is widespread in embryonic and early fetal periods and begins to function before the appearance of the common immune system in the developing organism. The first functional components of the SIS, such as IgG and IgA observed in this study, are most probably of maternal origin.

Adult↗
PubMed1996

Secretory component mRNA and protein expression in colorectal adenomas and carcinomas.

Secretary component (SC) is expressed basolaterally as a transmembrane protein (pIg receptor) on secretory epithelial cells. As pIg receptor it plays a central role in humoral immunity by mediating the external translocation of dimeric IgA and pentameric IgM. A few case reports have suggested that reduced or absent SC protein expression is associated with diarrhoeal disease, but there is no convincing evidence that a primary pIg receptor deficiency can occur. In this study the relative presence of SC mRNA was determined by Northern blot analysis and related to immunohistochemically determined SC protein expression in 33 colorectal adenomas (31 patients) with increased risk of developing sporadic colorectal cancer, as well as in 19 colorectal carcinomas from 19 patients with such sporadic tumours. In the adenomas, SC mRNA levels were positively related to SC protein expression; both mRNA and SC protein were negatively related to histological grade. Similarly, SC mRNA levels tended to be related to the SC protein expression in the carcinomas. SC mRNA was detected in all adenomas, and only two of ten carcinomas (10.5%) deemed to be SC deficient by immunohistochemistry also lacked SC mRNA expression, suggesting diallelic alterations in the SC-encoding gene (locus PIGR). This possibility agreed with Southern blot analysis performed on a separate sample of 32 other colonic carcinomas in which the diallelic loss of D1S58 (which exhibits a close linkage centromerically to PIGR) was calculated to be 6.4%. Together these findings suggested that reduced SC protein expression in colorectal adenomas might be a transcriptional defect reflecting the degree of cellular dysplasia, whereas absent SC protein expression in colorectal carcinomas might also involve post-transcriptional defects and occasional diallelic gene deletions representing late events in carcinogenesis.

Adenoma↗
PubMed1974

Localization of free and bound secretory component in human intestinal epithelial cells. A model for the assembly of secretory IgA.

Antibody reagents were made specific for each of the two forms of human SC, FSC and BSC, which is an integral part of the sIgA molecule. With the fluorescent antibody method the cytological and histological localization of FSC, BSC, and alpha-chains has been studied in various human mucous membranes. SC was present in columnar epithelial cells of the intestines and in the cells of serous acini of bronchial and salivary glands. In contrast, SC was not found in intestinal goblet cells or cells of mucous acini of bronchial and salivary glands. In the columnar epithelial cells of the small and large bowel, FSC was present most prominently in the Golgi zone, and much less prominently in the apical cytoplasm. On the other hand, BSC and alpha-chains were located only in the apical cytoplasm in an overlapping manner. The results favor a model in which sIgA is assembled inside epithelial cells from SC, which was synthesized in the same cell, and IgA, which entered the epithelial cell after synthesis in and secretion by a plasma cell.

Animals↗
PubMed1992

Transient developmental expression of IgY and secretory component like protein in the gut of the axolotl (Ambystoma mexicanum).

We previously reported that a primitive vertebrate, the Mexican axolotl (Amphibian, Urodela) synthesizes two classes of immunoglobulins. IgM are present in serum early in the development, and represent the bulk of specific antibody synthesis after an antigenic challenge. IgY occur in the serum later during the development, and are relatively insensitive to immunization. We demonstrate in the present work, using immunofluorescence with specific Mabs, that IgY are expressed in the gut epithelium, as secretory molecules. Secretory IgY are well expressed in the stomach and intestinal mucosae of young animals from 1 month after hatching to the seventh month. Thereafter, IgY progressively disappear from the gut and become readily detectable in the serum of 9-month-old preadult immunologically mature animals. Axolotl IgY are closely associated in the gut to secretory component-like (SC) molecules that are well-recognized by antisera to the SC of different mammalian species. This is the first description, in a primitive tetrapode, of an immunoglobulin class that could be the physiological counterpart of mammalian IgA.

Ambystoma mexicanum↗