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At least 793 records · Page 44Linked to original sources
PubMed1988

Influence of the hypothalamic-pituitary axis on the androgen regulation of the ocular secretory immune system.

The purpose of the present investigation was to examine the influence of the hypothalamic-pituitary axis on the androgen regulation of the ocular secretory immune system. Studies included the following experiments: (1) Testosterone administration significantly increased the immunoglobulin A (IgA) and free secretory component (SC) levels in tears of adult, orchiectomized and sham-hypophysectomized rats, as compared with those in tears of saline-treated controls. (2) Hypophysectomy completely inhibited this androgen effect. (3) Transfer of the pituitary to under the kidney capsule in orchiectomized and hypophysectomized rats did not restore the physiological conditions required for testosterone's stimulation of tear IgA and SC. (4) Selective ablation of the anterior pituitary gland also interfered with the testosterone-induced elevation of tear IgA and SC content. (5) Treatment of orchiectomized and/or hypophysectomized rats with rat prolactin, growth hormone, alpha-melanocyte-stimulating hormone or vehicle for 4 days had no effect on tear SC and/or IgA levels. Overall, these findings demonstrate that an intact hypothalamic-pituitary axis either supports or mediates the androgen control of the secretory immune system in the eye.

Animals↗
PubMed1994

Transcytosis of the polymeric immunoglobulin receptor is regulated in multiple intracellular compartments.

Transcytosis of the polymeric immunoglobulin receptor (pIgR) can be experimentally divided into three steps: 1) internalization from the basolateral plasma membrane and delivery to basolateral early endosomes, 2) microtubule-dependent movement from basolateral early endosomes to apical recycling endosomes, and 3) delivery from apical recycling endosomes to the apical surface and cleavage of the pIgR to secretory component, which is released into the apical medium. Transcytosis of the pIgR is stimulated by two signals, phosphorylation of Ser-664 in the cytoplasmic domain of the pIgR and binding of the ligand, dimeric IgA, to the pIgR. These signals do not detectably alter step 1 of transcytosis. Here, we show that phosphorylation of Ser-664 stimulates both steps 2 and 3, whereas binding of dimeric IgA stimulates only step 3 of transcytosis.

Animals↗
PubMed1991

IgM in the airways of asthma patients.

In order to obtain information on the role of IgM in the pathogenesis of asthma, we assayed IgM in the broncho-alveolar lavage fluid (BALF) from 14 non-smoking patients with asthma and 9 non-smoking healthy persons, using an ELISA. The concentrations of IgM in the epithelial lining fluid (ELF) were calculated on the basis of urea in serum and BALF. The concentrations of IgM in ELF after correction for serum IgM, cQIgM, from the patients as a group were higher than those from controls (Mann-Whitney U test, p less than 0.05). The IgM in BALF and serum, analysed by sucrose density gradient centrifugation was pentameric. The transudation of IgM from blood into ELF was compared with that of alpha 2 macroglobulin (A2M), a protein with a similar molecular mass. In 6 patients the cQIgM/cQA2M value was above the upper value of the range for controls suggesting abnormal local production of IgM. The presence of the secretory component (SC) linked to IgM was determined by ELISA. The percentage of SC-IgM in BALF was increased in 5 out of 7 patients tested. The increased local IgM concentrations and its increased local production may suggest a role for local IgM-mediated reactions in the inflammatory events associated with asthma.

Adolescent↗
PubMed1988

Proliferative and secretory activity in human breast during natural and artificial menstrual cycles.

Events of cell proliferation have been assessed by thymidine labeling index (TLI) in morphologically normal breast lobules from women of reproductive age. TLI is higher during the second half of the menstrual cycle both in women with natural menstrual cycles and in those with artificial cycles due to oral contraceptive (OC) use. TLI varies between 0.04% and 5.7% and declines with increasing age. There is no difference in mean TLI between OC users and nonusers if correction is made for the difference in age distribution between these two groups. Immunohistochemical detection of immunoglobulin A (IgA), secretory component (SC), and alpha-lactalbumin shows more frequent positive staining during artificial than natural menstrual cycles, and positive staining tends to be associated with higher TLI values. No significant variation in staining with cycle phase is detected in natural or artificial cycles. These results show that breast tissue does not resemble endometrium in the relationships that exist between proliferation, secretion, and menstrual cycle phase.

Adult↗
PubMed1995

Secretory monoclonal IgA class-switch variants against bacterial enteric pathogens in bile and intestinal secretions.

In a previous study we analyzed the molecular forms of monoclonal IgA class-switch variants (moIgA variants) and their transport into murine respiratory secretions. The aim of the present study is to characterize the transport of moIgA variants into bile and intestinal secretions so that their applicability in a passive immunization model of the gut can be evaluated. Different moIgA variants were directly isolated from IgG1 and IgG2a producing hybridoma clones specific for the same surface determinants of bacterial enteric pathogens (Salmonella typhimurium and Campylobacter jejuni) as their respective parent IgG clones. Hepatobiliary transport experiments clearly revealed the selective transport of biologically active polymeric forms of the IgA variants into the murine and rat bile after intravenous injection. Biotinylation of polymeric IgA variants prior to intravenous injection resulted in the recovery of functional, labeled SIgA. Moreover biotin-labeled polymeric IgA variant was recovered in bile with an increased molecular weight, suggesting that the secretory component had been added during passage through the liver. When IgA variant and IgG parent clones were both used in a murine backpack tumor model for passive immunization, IgA variant was selectively transported into intestinal secretions in comparison to IgG. The experimental model described here is suitable for use in comparative studies on the role of IgA and IgG with identical specificity in invasive infections of the intestinal tract.

Animals↗
PubMed2005

Transient expression of polymeric immunoglobulin receptor in human adenocarcinoma cell line HT-29.

Human polymeric immunoglobulin receptor (pIgR) protein was expressed in the adeno-carcinoma cell line HT-29 using a recombinant vaccinia virus transfection method. The pIgR protein was detected as 110- and 120-kDa bands by immunoprecipitation after metabolic labeling. PIgR was released as a free secretory component into the culture supernatant and was detected as a 110-kDa band. PIgR cleavage was investigated by adding the proteinase inhibitor leupeptin or protein kinase C activator PMA. Consistent with previous observations in the Madin Darby canine kidney cell system, cleavage of pIgR was inhibited by leupeptin and enhanced by PMA stimulation, thus indicating that it is regulated by common mechanisms. This experimental system should be very useful for pIgR investigation.

Culture Media↗
PubMed1988

[An immunohistological study of metastatic adenocarcinoma of the lymph node: is it useful in diagnosing a primary tumor?].

An immuno-histological study of metastatic adenocarcinoma has revealed the following results. Metastatic adenocarcinomas of the lymph-node of pulmonary and colonic origin were positive for CEA and negative for lysozymes, and those from gastric, pancreatic, and gallbladder tumors were positive CEA and lysozymes, and those from gastric and pancreatic tumors were positive for the secretory component. The prostate specific antigen was exclusively positive for metastatic prostatic adenocarcinoma with a low frequency and prostate acid phosphatase had many false positive results. Thyroglobulin was found to be positive only to colloid. Lactalbumin showed no specificity to metastatic breast adenocarcinoma. For achieving the final diagnosis of a primary tumor, its location in lymph nodes, the clinical history and the results of other examinations must also be taken into consideration.

Adenocarcinoma↗
PubMed1995

Molecular cloning of the mouse polymeric Ig receptor. Functional regions of the molecule are conserved among five mammalian species.

Transcytosis of polymeric Ig (pIg) by mucosal epithelial cells is mediated by the polymeric Ig receptor (pIgR). Here we describe the characterization of a 3095-bp mouse pIgR cDNA, which encodes a protein of 771 amino acids. Northern blot analysis detected a single mouse pIgR transcript of 3.9 kb, expressed at high levels in small intestine and liver, and at low levels in lung. Alignment of the amino acid sequences of mouse, rat, human, bovine, and rabbit pIgR revealed that functional regions of the molecule are conserved across species. In the extracellular region, conserved motifs include: a 23-amino acid pIg-binding site, 11 intradomain disulfide bonds, consensus sites for N-glycosylation, and a putative cleavage site at which the extracellular region of pIgR (secretory component) is released from the plasma membrane. A 10-amino acid sequence within the transmembrane region is highly conserved, possibly reflecting a mechanism for transmitting signals from the extracellular region to the cytoplasmic tail. Conservation within the cytoplasmic tail of pIgR is clustered in motifs that mediate polarized sorting, endocytosis, and transcytosis.

Amino Acid Sequence↗
PubMed2026

Sec and Tat Mediated Secretion Safeguards Mycobacterium tuberculosis Membrane Homeostasis.

Protein secretion is essential for the growth and virulence of Mycobacterium tuberculosis, yet the organization and function of its secretion pathways remain poorly understood. We reviewed the existing literature, combined it with systematic queries, and finalized annotations based on experimental data and computational predictions to compile a curated list of 92 secretory components and 198 reactions involved in Sec, twin-arginine translocation (Tat), and ESX pathways. Using CRISPRi, targeted depletion of SecA1 or TatAC impaired both in vitro growth and ex vivo survival. Label-free quantitative secretome analysis revealed decreased export of substrates dependent on SecA1 and TatAC, with enrichment of cytosolic proteins in culture filtrates, indicating increased membrane dysbiosis. Membrane proteomics showed elevated levels of proteins engaged in intermediary and lipid metabolism, while proteins associated with the cell wall and cell processes decreased, suggesting weakened membrane integrity. Loss of SecA1 or TatAC increased membrane permeability, with the effect being more pronounced in the case of TatAC, and caused structural abnormalities seen under electron microscopy. Overall, our integrated multi-omics and functional genetics studies demonstrate that the SecA1 and Tat pathways are essential for maintaining membrane homeostasis in Mycobacterium tuberculosis. These results suggest that essential secretory proteins may be promising targets for therapeutic intervention.

Mycobacterium tuberculosis↗
PubMed1988

Polymeric IgA antibody response to rabbit antithymocyte globulin in renal transplant recipients.

Treatment of transplant recipients with heterologous antithymocyte globulin (ATG) can induce the production of antibodies to the ATG itself. Such responses have, however, not been fully defined in terms of the kinetics, class, and quantities of antibodies produced. We have studied these parameters in 32 renal transplant recipients who had received rabbit ATG as treatment for acute rejection episodes. Antibodies to rabbit IgG were detected in the sera of all patients; employing an enzyme-linked immunosorbent assay (ELISA), the majority of patients were shown to produce specific antibodies of the IgG, IgA, and IgM class. Anti-ATG antibodies were first detected 6-48 days after the initial injection of ATG and usually attained peak values within 23 days. The IgM and IgA responses decreased within 1-2 months, whereas the IgG response remained elevated for 2-12 months. Gel filtration studies indicated that the IgA and IgM antibodies directed to the rabbit ATG were polymeric. Furthermore, the polymeric IgA bound secretory component, indicating the presence of J chain. In 6 patients, circulating immune complexes that contained rabbit IgG were detected. The clinical symptoms and laboratory findings did not correlate with the production or quantities of the different classes of antibodies. Possible explanations for the prominent IgA response to intravenous injections of ATG are discussed.

Adult↗
PubMed1993

Influence of severe protein malnutrition on rat lacrimal, salivary and gastrointestinal immune expression during development, adulthood and ageing.

The objective of the present study was to examine and to compare the impact of severe protein malnutrition during development, adulthood and ageing on secretory immune expression in the eye, mouth and small intestine. In addition, we sought to determine whether potential abrogation of mucosal immunity by protein deprivation might be reversed by the administration of a balanced diet. Weanling, adult and aged rats were provided isocaloric diets containing 24% (control), 19%, 14%, 10%, 6% and/or 3.2% protein levels for defined periods and various immunological parameters were evaluated before, during and after the dietary regimen. Our results demonstrated the following. (1) Severe protein malnutrition (3.2%) dramatically suppressed the secretory immune system in eyes of weanling rats. After 8 weeks of protein insufficiency, tear IgA concentrations in young rats had undergone a precipitous decrease, such that IgA could not be detected in tears. This response was paralleled by a significant decline in the tear volume, tear secretory component (SC), IgG and total protein content, number of IgA-containing cells in lacrimal tissue, as well as the amounts of SC and/or IgA in saliva, intestinal secretions and serum. In contrast, the immunological effects of protein malnutrition in adult or aged animals varied considerably depending upon the specific mucosal site. (2) The influence of protein deprivation was dose dependent and reversible: maintenance of weanling rats on 10%, 6% or 3.2% protein diets interfered with the establishment of ocular and intestinal mucosal immunity, but later administration of optimal diets to these malnourished animals permitted a rapid immune recovery. (3) The impact of protein malnutrition on tear IgA levels in weanling animals, as shown by pair-feeding experiments, appeared to reflect primarily protein deficiency and not caloric restriction. Overall, these findings show that dietary protein plays a significant, site-specific role in the developmental expression of the secretory immune system.

Aging↗
PubMed1989

Cellular and humoral immune responses in Campylobacter pylori-associated chronic gastritis.

Gastric cellular and humoral immune response investigated by immunoperoxidase staining of 53 antral biopsies showed significant differences in Campylobacter pylori-associated gastritis as compared with non-bacterial chronic gastritis and normal controls. IgA, secretory component, and complement C3 coated bacilli were seen in all cases of active chronic gastritis. C3 was always associated with coating by IgA, IgM, or both, which were rarely seen in gastritis without polymorphonuclear neutrophil infiltration. Intraepithelial mononuclear cellular infiltration was seen in 18 of 26 cases of C. pylori-associated chronic gastritis. The intraepithelial mononuclear cells stained positively for T cells and histiocytes.

Antibody Formation↗
PubMed1989

Molecular characteristics of IgA in infant saliva.

Saliva was collected from 57 infants aged 6 weeks to 2.5 years and the molecular form of IgA was studied by centrifugation on sucrose density gradients. Two distinct populations were identified. Seventy-two per cent of the children had secretory IgA in their salivary secretions, while 28% had a molecular form corresponding to monomeric IgA. No samples with concurrent monomeric and secretory forms were detected. Monomeric IgA was not detected in any infant over 12 months of age. Secretory component was detected in all samples but was not associated with monomeric IgA. Forty-seven per cent of the samples contained IgA fragments of approximately 40,600 molecular weight. The presence of fragments dominated in the group of children with monomeric IgA. The presence of monomeric IgA in infant saliva did not result from degradation due to storage or proteolysis. The study demonstrated an apparent maturation sequence in the molecular form of IgA present in the salivary secretions of infants.

Adult↗
PubMed1979

Infantile jejunal mucosa in infection and malnutrition.

Sixteen children with refractory diarrhea and three malnourished children who had frequent episodes of acute gastroenteritis but little diarrhea at the time of hospital admission, were studied by peroral upper small intestinal biopsy. Six children were adequately nourished; five children weighed 62 to 79% of expected weight and eight weighed less than 60% of expected weight. Two of the malnourished children had giardiasis. Pathogenic bacteria were found in only one case. Varying degrees of mucosal atrophy with reduction of mean villous height were seen in 18 cases. The concentration of mononuclear inflammatory cells and plasma cells was about half that seen in well-nourished children with severe nongastrointestinal infections. The concentration of mononuclear cells in the lamina propria was about twice that seen in normal adults. The proportions of IgA-producing cells and cells that stained for secretory component were significantly reduced, as compared with normal adult control values. This reduction was most striking in children with malnutrition complicated by giardiasis. Enzyme histochemical studies were performed for leucine aminopeptidase, alkaline phosphatase and acid phosphatase. There was a tendency for considerably reduced acid phosphatase activity in all clinical groups (kwashiorkor, marasmic kwashiorkor and marasmus) of growth-retarded infants.

Child, Preschool↗
PubMed1982

Immunoglobulin class of sperm antibodies in cervical mucus from infertile women.

By immunoaffinity chromatography using anti-IgG, anti-IgM, and anti-IgA coupled to CNBr-activated sepharose 4B, the immunoglobulin class of sperm-agglutinating antibodies was investigated in cervical mucus from four infertile women. In all patients, it was found that the sperm antibodies in cervical mucus belonged to the IgA class, whereas in serum, which was studied in two of the patients, IgG sperm antibodies were demonstrated. Absorption of the four cervical mucus samples with anti-secretory component sepharose 4B revealed that the IgA antibodies in at least two of the samples were SC-IgA antibodies. Investigation of a third sample by sucrose gradient ultracentrifugation revealed that the IgA sperm antibodies were characterized by a sedimentation coefficient between 9S and 13S, strongly suggesting the presence of SC-IgA antibodies. Accordingly, the sperm-agglutinating antibodies were SC-IgA antibodies in at least three of the four samples studied.

Absorption↗
PubMedDate not supplied

Immunohistochemical study of murine middle ear and Eustachian tube.

The localization of the immunocompetent cells and secretory component (SC) of the middle ear and Eustachian tube (ET) was investigated in healthy, non-immunized BALB/c mice, using immunohistochemical methods. Utilizing specific antisera against murine cell associated antigens and SC, we investigated the distribution of macrophages and granulocytes (Mac-1+ cells), helper T cells (Lyt-1+ cells), suppressor/cytotoxic T cells (Lyt-2+ cells), immunoglobulin-bearing cells (IgA, IgG, IgM) and SC in the middle ear and ET. Mac-1+ cells were found to be the most predominant cell type, followed in descending order by Lyt-1+ cells, IgA+ cells, Lyt-2+ cells, IgG+ cells and IgM+ cells. Lyt-1+ cells were found in the lamina propria, whereas Lyt-2+ cells were detectable in the epithelium of the ET. SC was seen predominantly within the tubal and glandular epithelial cells. These findings suggest that the distribution of the immunocompetent cells and SC in the ET is similar to that seen in secretory immune sites elsewhere in the body.

Animals↗
PubMedDate not supplied

[Identification of mucin-secretion characteristics in cells from serous effusions: consideration of histochemical and immunohistochemical aspects].

Fourty-two cell-blocks of serous effusions (thirty malignant and twelve reactive) were tested by anti Secretory Component Ab (policlonal) using the s.-Ab method, and by histochemical tests: PAS, PAS Diastase and Alcian blue pH 2.5. Immunohistochemical and histochemical features were compared to identify their meaning and correlation in epithelial mucin detection. This study suggests the evident correlation between SC and PAS diastase (better than between SC and Alcian blue) and possibility to replace the old traditional test of PAS diastase with anti SC antibody (much more sensible than PAS diastase) in routine mucin detection histochemical tests.

Alcian Blue↗
PubMed1994

Interaction between streptococcal protein Arp and different molecular forms of human immunoglobulin A.

Protein Arp, the IgA-binding protein of the group A Streptococcus, has affinity for the Fc-part of IgA. The binding between protein Arp and several different molecular forms of human IgA was characterized. It was found that protein Arp bound with higher affinity to uncomplexed forms of IgA than to complexed forms (secretory IgA, alpha 1-antitrypsin-IgA and alpha 1-microglobulin-IgA). Thus, the affinity constant was 2.0-5.9 x 10(8) M-1 for the binding to monomeric, dimeric, trimeric, and quadrimeric IgA, and 4.5-5.0 x 10(7) M-1 for binding to the complexed forms. Among the uncomplexed IgA-molecules, the affinity constant was in the same range for J chain-containing forms (dimeric, trimeric and quadrimeric IgA) as for forms without J chain (monomeric and a particular quadrimeric IgA devoid of J chain). Western blotting demonstrated that protein Arp bound exclusively to the alpha-chain of all IgA-forms. Several lines of evidence pointed to a localization of the binding site to the C alpha 3-domain. First, protein Arp did not bind to three N-terminal alpha-chain fragments which lacked a region corresponding to the C alpha 3-domain, including that form a four-chain myeloma IgA, naturally occurring in plasma. Second, the binding to dimeric and tri/quadrimeric IgA was partially blocked by an added secretory component, which has been suggested to bind to the C alpha 2- and C alpha 3-domains of the alpha-chain. Finally, alpha 1-antitrypsin and alpha 1-microglobulin, in the weakly binding IgA-complexes, have been shown to be linked to the C alpha 3-domain via the penultimate amino acid residue of the alpha-chain peptide, supporting the hypothesis of a localization of the binding site of protein Arp to the C alpha 3-domain.

Bacterial Proteins↗