Search PubMed⌕ Search

Biomedical subjects

J Mestecky

Publications and source records attributed to J Mestecky.

At least 91 records · Page 5Linked to original sources
PubMed1994

Molecular characterization of protein Sir, a streptococcal cell surface protein that binds both immunoglobulin A and immunoglobulin G.

Cell surface proteins that bind to the Fc part of immunoglobulin (Ig) A and/or IgG are expressed by many strains of the group A Streptococcus, an important human pathogen. Two extensively characterized proteins in this group of molecules are protein Arp that preferentially binds IgA and protein H that binds IgG. In addition, recent work has shown that many group A streptococcal strains express a novel type of Fc-binding protein, designated protein Sir, that binds both IgA and IgG. Protein Sir22, the molecule expressed by a strain of serotype M22, has now been purified and characterized after expression of the cloned gene in Escherichia coli. Dot-blot analysis with a large number of purified monoclonal Igs showed that protein Sir22 reacted with 19 out of 20 IgA proteins and with 19 out of 24 IgG proteins. The affinity constants for the reactions between protein Sir22 and Ig were determined to be 7.0 x 10(8) M-1 for serum IgA, 2.4 x 10(8 M-1 for secretory IgA, and 7.8 x 10(8) M-1 for IgG. Inhibition experiments showed that the bindings of IgA and IgG to protein Sir22 were mutually exclusive, indicating shared or contiguous binding sites. Analysis of the sequence of the sir22 gene indicated a gene product with 365 amino acid residues, including a 41-residue signal peptide. The processed form of the protein, 324 residues, has a calculated M(r) of 37,168. Deletion analysis of the sir22 gene showed that a 156-residue NH2-terminal fragment of protein Sir22 retained the ability to bind both IgA and IgG. The overall organization of protein Sir22 is similar to that of the IgA-binding protein Arp and the IgG-binding protein H. All three of these proteins are members of the M protein family and have a central repeat region of the C type.

Amino Acid Sequence↗
PubMed1994

Oral tolerance in humans. T cell but not B cell tolerance after antigen feeding.

The purpose of this study was to investigate whether oral tolerance, defined as Ag-specific immunologic unresponsiveness after Ag feeding, could be induced in humans after prolonged Ag ingestion. Eight adult volunteers ingested a total dose of 0.5 g of keyhole limpet hemocyanin (KLH) followed by subcutaneous immunization with KLH. Eight controls received only the subcutaneous immunization. In the group fed KLH, there was a significant reduction in KLH-specific T cell proliferation (p = 0.04) and delayed skin test responses (p = 0.07) to KLH. KLH ingestion alone did not induce significant levels of Abs in either serum or secretions. However, after the subsequent subcutaneous immunization, the number of circulating IgG and IgM anti-KLH-producing cells, the titers of serum IgG, IgA, and IgM anti-KLH Abs, and the titers of IgA anti-KLH Abs in saliva and intestinal secretions were significantly greater in the KLH-fed group than in the nonfed group. We conclude that KLH feeding induced systemic T cell tolerance, but B cell priming, at both systemic and mucosal sites. These studies support the concept of using Ag feeding as a treatment for certain immune-mediated diseases.

Administration, Oral↗
PubMed1994

Suppression of the immune response by nasal immunization.

Intranasal immunization results in both a mucosal and a systemic immune response in humans. Intranasal tetanus toxoid immunization in humans causes an increased serum IgA1 antibody response to tetanus toxoid following a subsequent intramuscular immunization. We hypothesized that intranasal priming with a novel protein antigen, keyhole limpet hemocyanin (KLH), would similarly result in an up-regulated systemic IgA response after a subsequent systemic immunization. To test this hypothesis, five healthy adults received a primary series of intranasal KLH immunizations followed 3 months later by a subcutaneous KLH immunizations Eight healthy adults received only a subcutaneous KLH immunization and served as controls. The nasal immunization resulted in a brisk and sustained serum IgM, IgA, and IgG antibody response and a mucosal IgA response. The subcutaneous immunization alone resulted in a serum antibody response and the development of delayed type hypersensitivity by skin testing. When the nasally primed subjects received a subsequent subcutaneous immunization there was a decline in the serum concentration of IgA and IgG antibodies to KLH. In addition, the nasally primed subjects failed to develop delayed type hypersensitivity to KLH following subcutaneous immunization. These data suggest that the nasal mucosa can induce a mucosal and systemic response; however, it may also suppress a subsequent immune response to systemic immunization.

Administration, Intranasal↗
PubMed1994

Carbohydrate heterogeneity of human myeloma proteins of the IgA1 and IgA2 subclasses.

Comparative studies of the N-linked carbohydrate chains of human myeloma proteins of the IgA1 and IgA2 subclasses were performed. The N-linked carbohydrate chains were released by hydrazinolysis from the polypeptide backbone, converted to radioactive oligosaccharides by sodium borotritide reduction after N-acetylation and separated into one neutral and two acidic fractions by paper electrophoresis. The acidic oligosaccharides were completely converted to neutral oligosaccharides by sialidase treatment, indicating that they were sialyl derivatives. The neutral and sialidase-treated acidic oligosaccharides were further fractionated by Bio-Gel P-4 column chromatography. Structural studies of each oligosaccharide by sequential exoglycosidase digestion and methylation analysis revealed that human myeloma IgA proteins contained significant amounts of biantennary complex-type carbohydrate chains in addition to a small amount of the high mannose-type. The results indicated that the oligosaccharide structures of human IgA1 and IgA2 display a high degree of heterogeneity not only in the number of carbohydrate chains, but also in their composition.

Anions↗
PubMed1994

Intraperitoneal immunization of human subjects with tetanus toxoid induces specific antibody-secreting cells in the peritoneal cavity and in the circulation, but fails to elicit a secretory IgA response.

Five patients on continuous ambulatory peritoneal dialysis (CAPD) were immunized intraperitoneally with tetanus toxoid (TT) through an indwelling catheter. Four control patients on CAPD received the same dose of TT intramuscularly. Before immunization, virtually no anti-TT antibody-secreting cells (AbSC) were detected by the enzyme-linked immunospot (ELISPOT) assay in peripheral blood or peritoneal fluid from patients of either group. One to 2 weeks after immunization, high frequencies of TT-specific AbSC were detected in the circulation and peritoneal cavity. More than 80% of those cells were of the IgG isotype, with IgA accounting for most of the remainder. Patients receiving TT by the i.p. route showed significantly higher frequencies of specific IgG and IgA AbSC in the peritoneal cavity than patients immunized intramuscularly. Frequencies of AbSC in peripheral blood did not significantly differ between the two groups. Immunization with TT by both routes resulted in a significant increase of IgG anti-TT antibodies in serum, saliva and peritoneal fluid. A significant IgA antibody response was seen only in serum and peritoneal effluents. Therefore, i.p. immunization of human subjects with TT elicited both a localized response in the peritoneal cavity as well as a systemic response in serum, but did not induce a salivary IgA response.

Adult↗
PubMed1994

Lectin receptors on IgA isotypes.

It has been shown previously that secretory IgA interacts with the mannose-specific lectin of Escherichia coli. The purpose of the study described here was to evaluate whether the N-linked oligosaccharide chains of the human IgA isotypes IgA1 and IgA2 differ in lectin receptor activity. A range of plant lectins specific for N-linked oligosaccharide chains were tested for their ability to precipitate IgA1 and IgA2 myeloma proteins, secretory IgA and free secretory component. IgA2 myeloma proteins reacted more strongly than IgA1 with the mannose-specific lectin ConA, whereas IgA1 myeloma proteins reacted more strongly than IgA2 with two galactose-specific lectins, Ricinus communis agglutinin I and Abrus precatorius agglutinin. This suggests that IgA2 possesses a larger proportion of short truncated complex type oligosaccharide chains and/or oligomannose type chains than IgA1. Further, IgA2 reacted more strongly than IgA1 myeloma proteins with Lens culinaris (lentil) lectin, and Pisum sativum (pea) lectin, suggesting that IgA2 exposes more of short, complex type chains fucosylated on the core than IgA1. The differences demonstrated in receptor activity between IgA1 and IgA2 may be important in their interaction with the microbial flora, as well with endogenous lectins, such as phagocyte receptors.

Carbohydrate Sequence↗
PubMed1994

Mucosal immunity and strategies for novel microbial vaccines.

Infectious diseases continue to be the leading cause of morbidity and mortality worldwide. Increased awareness of the fact that mucosal membranes are the most frequent portals of entry of pathogenic microorganisms has prompted studies aimed at the development of vaccination protocols and antigen delivery systems that would lead to an increased protection of mucosae. Although systemic and strictly local immunizations are of limited effectiveness in the induction of mucosal protection, ingestion or inhalation of antigens results in a generalized immune response manifested by the appearance of specific antibodies of the secretory immunoglobulin (Ig) isotype in external secretions due to the dissemination of IgA precursor cells from IgA-inductive lymphoid tissues. Furthermore, additional inductive sites strategically positioned at the opening of the respiratory and digestive tracts may also be suitable targets for induction of immune responses at desired effector sites. To prevent degradation and the increase of ingested antigens absorption, novel strategies including enclosure of antigens into biodegradable microspheres, liposomes or their expression in viral and bacterial vectors and plants are currently being considered. Forthcoming technological advances in antigen preparation and routes of delivery will undoubtedly have a profound impact on immunization practices in the future.

Animals↗
PubMed1994

Secretory immunity in the female reproductive tract.

PROBLEM: Antibodies and antibody-producing cells display a different and characteristic distribution in body fluids and tissues. METHOD: We have investigated the tissues of the female reproductive tract to determine whether the distribution of immunoglobulin-producing cells and the contents of cervical secretions were similar to those found in tissues of the secretory immune system. RESULTS: Immunohistochemical examinations of female genital tissues revealed the presence of plasma cells that secrete IgA (and in lower numbers IgM and IgG) especially in the subepithelial layers of the uterine endo- and ectocervix, fallopian tubes, and vagina. Both IgA1- and IgA2-producing plasma cells were found in approximately equal proportions. The presence of J-chain in the IgA-secreting cells suggests the synthesis of polymeric IgA (pIgA). Epithelial cells lining the fallopian tube and endocervix were positive for secretory component (SC), which is required for the transepithelial transport of pIgA into external secretions. Cervical mucus was collected and the molecular forms of IgA were separated using column chromatography. Approximately 80% of IgA in cervical mucus was polymeric compared with 55% in the vaginal fluid. CONCLUSIONS: These data indicate that all effector components of the mucosal immune system are present in the female reproductive tract. The immunization routes that lead to a secretory IgA (S-IgA) response need to be further explored.

Adult↗
PubMed1994

Mucosal immunity in the female genital tract: relevance to vaccination efforts against the human immunodeficiency virus.

The development of vaccines that induce specific immune responses in the genital tract secretions would have far-reaching implications for the prevention of AIDS and other sexually transmitted diseases. Most of the currently studied vaccines utilize systemic routes of immunization that are of limited value for the prevention of mucosa-contracted diseases. The relative contribution of antigen-sensitized cells and IgA-committed lymphocytes from IgA inductive sites (e.g., Peyer's patches and rectal tonsils) to remote or adjacent effector sites (e.g., salivary glands and female genital tract) as manifested by the appearance of corresponding secretory antibodies has not been studied in humans despite its unquestionable practical importance. Exploitation of immunization routes that are effective for induction of mucosal immune responses and reflect our current knowledge of the origin of antibodies and of specific antibody-forming cells in mucosal tissues is likely to reduce the incidence of many infectious diseases including AIDS.

AIDS Vaccines↗
PubMed1994

Antispermatozoal antibodies in human colostrum and milk.

Authors studied antisperm activity in human colostrum and milk by tray agglutination (TAT) and indirect mixed antiglobulin reaction (MAR) tests. Spermagglutination observed by TAT was found in 10 patients (24%) in colostrum, in 3 (5%) in milk. Character of spermantibodies by indirect MAR-test showed the presence of sIgA in 6 (14%), in IgG in 4 (9.5%) in colostrum, the presence of sIgA in 3 (4.8%), of sIgA and IgG together in 1 (1.7%) in milk. Authors discuss the origin of these antibodies.

Adult↗
PubMed1993

Surface expression of secretory component and HLA class II DR antigen on glandular epithelial cells from human endometrium and two endometrial adenocarcinoma cell lines.

The expression of secretory component (SC) by human glandular endometrial cells cultured in vitro was significantly increased by estradiol in the medium. Interferon-gamma and interleukin-4 stimulated the expression of SC only in the presence of estrogen. Tumor necrosis factor-alpha plus estrogen also caused a significant increase in the number of cells expressing SC. HLA class II antigen DR was detected on few glandular epithelial cells of human endometrium cultured in control medium, whereas interferon-gamma and interleukin-4, but not tumor necrosis factor-alpha, caused significant increases in the expression of DR. Estrogen in the culture medium did not significantly affect DR expression. The human endometrial adenocarcinoma cell lines, HEC and RL-95, expressed SC in approximately 50 and 20% of the cells. Also, approximately 20% of the RL-95 cells stained for DR antigen. Interferon-gamma did not influence the degree of expression of either surface marker of the two cell lines. Cells of both lines bound polymeric IgA and IgM but showed little to no binding of monomeric IgA, IgG, or an IgM previously shown not to bind SC.

Adenocarcinoma↗
PubMed1993

Interactions of cell-surface galactosyltransferase with immunoglobulins.

Detection of the activity of beta-1,4-galactosyltransferase (beta-1,4-GT) in suspensions of viable mouse hepatocytes, the human hepatoma cell line Hep G2, the human colonic adenocarcinoma cell line HT-29, the monocyte-like cell line U937, and human splenic B and T lymphocytes suggested the presence of beta-1,4-GT, in an enzymatically active form, on plasma membranes. The presence of beta-1,4-GT on cell surfaces was also indicated from the effect of trypsinization of live cells, which significantly reduced cell surface beta-1,4-GT activity, but did not affect the activity associated with cytoplasmic membranes. Furthermore, the presence of beta-1,4-GT on the cell surface was demonstrated by indirect immunofluorescence staining of cells with anti-beta-1,4-GT antibody. The detection of radioactivity in immunoglobulins (Ig) and their component chains after incubation with suspensions of intact cells in the presence of Mn2+ and UDP-[3H]-galactose, indicated that Ig molecules were galactosylated. In the absence of UDP-[3H]-galactose, beta-1,4-GT on cell surfaces, or immobilized on Sepharose-4B, formed stable complexes with galactose acceptors, including Ig. The efficiency of binding decreased in the order: J chain > alpha chain > mu chain > polymeric IgA2 > monomeric/polymeric IgA1 > IgM > IgG. Thus, beta-1,4-GT could act as a cell-surface receptor for Ig through a cation-dependent, lectin-like association of the beta-1,4-GT with the carbohydrate moieties of the Ig. This was confirmed by indirect surface immunofluorescence and radiolabeled ligand binding assays. The binding was inhibitable by EDTA, alpha-lactalbumin (in the presence of glucose), GlcNAc, or uridine 3',5'dialdehyde. At 37 degrees C, the apparent affinity constants and association rate constants of interaction between cell surface beta-1,4-GT on glutaraldehyde-fixed HT-29 and U937 cells and alpha 2 chain or monomeric IgA1 were in the range from 7.1 x 10(7) to 4.6 x 10(8) M-1 and from 1 x 10(5) to 3 x 10(6) M-1 s-1, respectively. The dissociation rate constants and half time of dissociation calculated from these data were in the range from 2.1 x 10(-2) to 5.0 x 10(-4) s-1 and from 33 to 1380 s, respectively. The number of alpha 2 or IgA1 molecules bound per HT-29 and U937 cell were in the range from 1.9 x 10(5) to 1.3 x 10(6). The binding of IgA by the cell surface beta-1,4-GT was not associated with internalization or the catabolic degradation of the ligand.

Animals↗
PubMed1993

Interactions of galactosyltransferase with serum and secretory immunoglobulins and their component chains.

Assay of the activity of beta-1,4-galactosyltransferase (beta-1,4-GT) revealed that in addition to serum, milk, colostrum, amniotic and cerebrospinal fluids and malignant effusions, this enzyme is present also in tears and saliva. Molecular-sieve chromatography of human colostral whey and serum and subsequent assay of beta-1,4-GT activity have shown that beta-1,4-GT was present as a free enzyme (55 kDa) and associated with components of larger molar mass. The elution pattern did not change when the chromatography was carried out in a buffer devoid of, or enriched with, Mn2+, a cofactor of beta-1,4-GT activity. However, the activity associated with the large molar mass components was absent when the chromatography was carried out in the presence of a chelating agent (EDTA). Analyses of the eluted material by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE), and by immunodiffusion indicated that the major colostral component in beta-1,4-GT activity-containing fractions was secretory IgA (S-IgA); in addition, the beta-1,4-GT activity was detected in fractions that contained lactoferrin and alpha-lactalbumin. Interactions of beta-1,4-GT with S-IgA and lactoferrin in colostrum were also demonstrated by the detection of radioactivity in precipitin lines obtained by immunoelectrophoresis and autoradiography of the colostral whey after it had been incubated with UDP-[3H]-galactose. Furthermore, radioactively labeled S-IgA and alpha-chain were detected when colostral whey incubated with UDP-[3H]-galactose was analyzed by SDS-PAGE under non-reducing and reducing conditions, respectively. In serum, the beta-1,4-GT-binding components identified in fractions after molecular-sieve chromatography were IgG, IgA, IgM and transferrin. The binding of beta-1,4-GT to immunoglobulins (Ig) was also demonstrated by assaying the beta-1,4-GT activity associated with Sepharose-4B-immobilized Ig of various isotypes and molecular forms, which were incubated with colostral beta-1,4-GT in the presence of Mn2+. Beta-1,4-GT measured by enzyme activity was bound to these Ig in order: polymeric IgA2 > monomeric IgA1 = polymeric IgA1 = secretory IgA = pentameric IgM > IgG. Immobilized component chains, namely alpha, mu and J chains, bound beta-1,4-GT more effectively than native Ig. Incubation of the IgA1 myeloma protein with crude human colostral galactosyltransferase in the presence of UDP[3H]-galactose and Mn2+ resulted in galactosylation of both N- and O-linked carbohydrate side chains.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗