Search PubMed⌕ Search

Biomedical subjects

J Mestecky

Publications and source records attributed to J Mestecky.

At least 163 records · Page 9Linked to original sources
PubMed1988

A novel two colour ELISPOT assay. I. Simultaneous detection of distinct types of antibody-secreting cells.

A novel assay system has been developed which is based on the ELISPOT methodology and employs a combination of two immunoenzyme visualization systems yielding distinct colour products. This variation permits the simultaneous enumeration of two different types of cell secreting antigenically distinct products. Optimal conditions for the concurrent detection of human mononuclear cells secreting IgG or IgA antibodies are described.

Adult↗
PubMed1988

The sites of catabolism of murine monomeric IgA.

The tissue sites of monomeric IgA (mIgA) catabolism were determined in a BALB/c mouse model. Mouse mIgA myeloma proteins were labeled either by direct iodination or by coupling the residualizing label, dilactitol-125I-tyramine (125I-DLT) to the proteins; catabolites from protein labeled with 125I-DLT accumulate at the site of protein degradation, allowing identification of the tissue and cellular sites involved in catabolism of the protein. The circulating half-lives of 125I- and 125I-DLT-mIgA were the same. The distribution of radioactivity in tissues was measured at 1, 3, 24, and 96 h after iv. injection of 125I-DLT-labeled mIgA, dimeric IgA (dIgA), IgG, or mouse serum albumin. The greatest uptake of 125I-DLT-mIgA was attributable to the liver. This organ accounted for more internal catabolism of mIgA than all other tissues combined. In contrast, 125I-DLT-IgG was catabolized equally in skin, muscle, and liver. These data indicate that, in mice, the liver is the major site of mIgA catabolism. To determine the cell types involved, collagenase digestion was used to isolate parenchymal and non-parenchymal cells from perfused liver of animals injected with 125-DLT-mIgA. Most of the radioactivity was associated with the hepatocyte fraction, even though both cell types showed uptake of 125I-DLT-mIgA. Inhibition studies, with asialofetuin and mouse IgA demonstrated that the uptake of mIgA by liver cells was mediated primarily by the asialoglycoprotein receptor.

Animals↗
PubMed1988

Systemic immunization with pneumococcal polysaccharide vaccine induces a predominant IgA2 response of peripheral blood lymphocytes and increases of both serum and secretory anti-pneumococcal antibodies.

Ig class-, and IgA and IgG subclass-specific immune responses to a 23 valent pneumococcal polysaccharide vaccine were studied at a single-cell level in the peripheral blood of systemically immunized adults. With a solid phase enzyme-linked immunospot (ELISPOT) assay, PBMC from immunized individuals were assayed for spontaneous Ag-specific antibody (Ab) production before, and on days 7, 14, and 28 after vaccination. On the day of immunization, no spontaneous Ag-specific Ab-secreting cells could be detected. On day 7 after vaccination, a high frequency of cells secreting Ab specific for pneumococcal polysaccharides (PPS) was observed. The IgA class comprised 79% (geometric mean) of the Ag-specific Ab-secreting cells, whereas IgG- and IgM-secreting cells accounted for 12% and 9%, respectively. The majority of Ag-specific IgA-secreting cells produced Ab of the IgA2 isotype. Serum, saliva, and tears collected before and on days 7, 14, and 28 after vaccination were assayed for specific Ab to the vaccine (anti-PPS Ab) by an ELISA. Serum IgA anti-PPS Ab showed the highest increase after vaccination with a 19-fold increase (geometric mean) which peaked on day 14. However, the ratio of Ag-specific polymeric vs monomeric IgA did not change after immunization. Serum IgG and IgM anti-PPS Ab displayed mean increases of 5.5-fold and 5.6-fold, respectively, on day 14. The most pronounced increase of salivary anti-PPS Ab was observed in the IgG class (4.5-fold on day 28) followed by IgM (4-fold on day 28), IgA (2.0-fold on day 14), IgA1 (2.4-fold on day 14) and IgA2 (2.0-fold on day 14). The levels of total IgA, IgG, and IgM in saliva did not change significantly throughout the course of immunization. IgG and IgM anti-PPS Ab levels in tears increased less than in saliva, whereas IgA behaved similarly as in saliva. There were no significant differences in the Ag-specific increase rates between the IgA, IgG, and IgM isotypes in tears.

Adult↗
PubMed1988

IgA nephropathy, the most common glomerulonephritis worldwide. A neglected disease in the United States?

Although its prevalence and clinical importance in the United States are stated to be low, we believe IgA nephropathy occurs as commonly in this country as in Western Europe. Initial reports suggested the disease was perhaps restricted to France and synonymous with "benign recurrent hematuria," but longer follow-up has proven both conclusions incorrect. Obviously, major gaps persist in our understanding of the immunopathogenesis and the natural history. The latency of the American investigative response calls for more intensive clinical and laboratory studies of the most common primary glomerulonephritis worldwide.

Antigen-Antibody Complex↗
PubMed1988

Receptor-mediated binding and uptake of immunoglobulin A by human liver.

We have studied the molecular mechanisms of the binding and uptake of secretory and serum immunoglobulin A (IgA) of both subclasses (1 and 2) and molecular forms (monomer and polymer) by the particulate fraction of human liver homogenate and by a human hepatoma cell line (HepG2). Inhibition by asialoorosomucoid and the requirement for the presence of calcium indicated that the binding of secretory IgA and polymeric IgA1 was mediated by the asialoglycoprotein receptor. Secretory component, which functions as a receptor for polymeric IgA in several animal species, was detected in the epithelial cells of bile ducts, but not in hepatocytes. Secretory IgA and all molecular forms and subclasses of serum IgA were bound by HepG2 cells, which do not express secretory component. The requirement for the presence of calcium, the presence of a terminal galactose residue in IgA, and the molecular weight of the major plasma membrane protein responsible for binding (41,700 daltons) indicated the involvement of asialoglycoprotein receptor. Immunoglobulin A proteins bound by HepG2 cells were endocytosed and catabolized.

Humans↗
PubMed1988

Binding of IgA to erythrocytes from patients with IgA nephropathy.

Primate erythrocytes (RBCs) may be involved in the transport and processing of C3b-containing immune complexes (IC). Compared to RBCs from healthy controls, increased amounts of IgA were detectable on RBCs from 7 of 17 patients with IgA nephropathy (IgA NP). There was no difference in the amount of IgG or IgM. The highest amount of RBC-bound IgA corresponded to 6 ng IgA/10(8) cells. The mechanisms involved in the binding of IgA to RBCs were investigated in vitro. Isolated IgA1 or IgA2 did not bind to RCBs from a patient with IgA deficiency. In contrast, incubation of RBCs with a polyethyleneglycol (PEG) precipitate of serum from a patient with IgA NP which contained IgA-IC resulted in IgA1 binding. However, this binding was not inhibited by monoclonal anti-CR1 or by an excess of IgG or IgM. Factor I did not cause release of IgA from RBCs from patients with IgA NP. Heat-aggregated IgA1 also bound to RBCs and this binding was not affected by the presence of complement. We conclude that minute amounts of IgA-IC are bound to RBCs by a complement- and Fc receptor-independent mechanism. The quantity of IgA-IC associated with RBC is so small that it is unlikely to represent an important in vivo route of IgA-IC transport or processing.

Antigen-Antibody Complex↗
PubMed1988

IgA-mediated clearance and tissue deposition of dinitrophenylated human serum albumin at various DNP:HSA ratios.

Dinitrophenylated human serum albumin (DNP-HSA) with various DNP:HSA ratios was prepared by direct conjugation with dinitrobenzene sulfate or with a caproic acid spacer group (DNP-cap-HSA) using DNP-epsilon-amino-caproic acid N-hydroxy-succinimide ester. The substitution ratio and chemical linkage (presence of a spacer group) were shown to affect the degree of murine anti-DNP antibody binding to antigen, and hence the tissue deposition and efficiency of hepatobiliary transport. DNP-HSA (4.5:1), which poorly binds to IgA anti-DNP antibody, is inefficiently transported into mouse bile. In contrast, 9:1 DNP-cap-HSA readily forms complexes and is more effectively cleared by the hepatobiliary route. The IgA-mediated increase in liver deposition of DNP-cap-HSA (9:1) was found to be associated with an increase in antigen uptake by hepatocytes. In contrast, large complexes formed between DNP-HSA (49:1) and IgA anti-DNP antibody are taken up by nonparenchymal cells of the liver and thus are inefficiently transported into bile. These results suggest that the IgA-mediated uptake by phagocytic cells or hepatocytes of haptenated protein strongly depends on the degree of haptenation.

Animals↗
PubMed1988

Role of hepatocytes in the uptake of IgA and IgA-containing immune complexes in mice.

The role of parenchymal and nonparenchymal mouse liver cells in the uptake of polymeric IgA (pIgA) and pIgA-containing immune complexes (IC) of low mol. wt (less than 1 x 10(6)) was studied. As detected by immunofluorescence and immunoelectron microscopy, pIgA were bound on the surface of isolated hepatocytes. Following the injection of radiolabeled pIgA or pIgA-IC into mice, the total radioactivity recovered from isolated liver cells was preferentially associated with parenchymal cells. The ability to inhibit the transport of pIgA and pIgA-IC by pIgA of an irrelevant specificity suggests that pIgA-IC and pIgA are bound and transported by the same mechanism. These results indicate that mouse hepatocytes are involved in the uptake and hepatobiliary transport of pIgA and pIgA-IC of low mol. wt.

Animals↗
PubMed1988

Immunobiology of IgA.

In humans, IgA is produced in quantities larger than those of all other immunoglobulin isotypes combined. In comparison with immunoglobulin of other isotypes, human IgA displays a unique heterogeneity of its molecular forms with a characteristic distribution in various body fluids. Serum IgA is represented by predominantly monomeric molecules of the IgA1 subclass and is produced mainly in the bone marrow, while in external secretions most of the IgA, produced locally in mucosal tissues, occurs in the polymeric configuration with a relatively increased proportion of IgA2 molecules. Cells that produce monomeric or polymeric IgA and IgA1 or IgA2 molecules are characteristically distributed in various lymphoid and nonlymphoid tissues. The differential interactions of monomeric and polymeric IgA molecules with various cells lead to their selective distribution in body fluids and to differences in the effector functions. Contrary to immunoglobulins of other isotypes, IgA participates in the disposal of antigens by mechanisms mostly devoid of inflammatory consequences. Various modes of immunization can induce an immune response in the systemic and/or secretory IgA compartments. Although most of the total serum IgA is momomeric, recent studies indicate that specific serum IgA antibodies induced by either mucosal or systemic immunizations with microbial antigens appear first in the polymeric form. Thus, cautious immunochemical analyses of IgA antibodies in systemic and secretory compartments with respect to their kinetics of appearance, monomeric and polymeric forms, and subclass may elucidate their tissue origin and character of the antigen involved in their induction.

Chemical Phenomena↗
PubMed1988

Precursor B cells transformed by Epstein-Barr virus undergo sterile plasma-cell differentiation: J-chain expression without immunoglobulin.

Human bone marrow cells were depleted of B lymphocytes to enrich for precursor B cells that could be transformed with Epstein-Barr virus. Transformed immunoglobulin-negative precursors either maintained their immunoglobulin genes in the germ-line configuration or had undergone DJ or abortive VDJ rearrangements (V, D, and J represent variable, diversity, and joining gene segments). All cell lines and their derivative clones, even those with no detectable immunoglobulin gene rearrangements, generated subpopulations of cells that produced high levels of joining (J) chain when analyzed by immunoprecipitation after biosynthetic labeling and by blot hybridization of cytoplasmic RNA. Morphologic and immunofluorescence analyses revealed that J-chain production was confined to clonal progeny that had exited the cell cycle to undergo plasma-cell differentiation. Analysis of cell surface antigens revealed expression of several B-cell maturational markers, including complement receptor type 2 (CR2) and plasma cell antigen 1 (PCA-1). Epstein-Barr virus can thus transform B-cell progenitors, allowing them to proliferate and undergo terminal B-cell differentiation coupled with J-chain expression. These events appear to occur independently of the immunoglobulin gene status of the transformed cells.

Agammaglobulinemia↗
PubMed1988

Autoimmunity to collagen in adult periodontal disease.

Although it has been documented that exogenous antigens of microbial origin are involved in the induction of the local inflammatory responses in human adult periodontitis (AP), endogenous antigens may contribute to the chronicity of this common disease. In this study, we used the enzyme-linked immunospot (ELISPOT) test to enumerate antibody-secreting cells to human collagen Types I-VI by cells isolated from the gingivae and peripheral blood of AP patients. Analyses of dissociated cells from gingivae of 39 AP patients revealed the presence of high numbers of cells that secrete antibodies to Type I collagen, and to a lesser extent, Type III. Although the majority of such cells produced specific antibodies of the IgG class, IgA- and IgM- anti-collagen -secreting cells were also detected. When compared to the total antibody-producing cells, the numbers of cells forming specific antibodies to collagen Type I were surprisingly high. In contrast, anti-collagen antibody-producing cells were rarely detected in the peripheral blood of patients with adult periodontal disease and only low levels of anti-collagen antibodies were present in the serum. The finding of local production of anti-collagen antibodies in AP suggests that autoimmunity may contribute to the pathogenesis of this common disease.

Antibody-Producing Cells↗
PubMed1988

HNK-1+ (Leu-7) cells and natural killer cell activity in inflamed human gingival tissue.

The presence of HNK-1 (Leu-7)-positive cells and natural killer (NK) cell activity was determined in human periodontal tissues. Gingival tissues obtained from 25 adult patients were processed for analysis utilizing a HNK-1 (Leu-7) mouse monoclonal antibody. A subpopulation of non-adherent lymphoid cells obtained by collagenase digestion of inflamed gingival tissues from 10 patients was examined for the presence of large granular lymphocytes (LGL) by May-Grünwald-Giemsa staining and for NK cell activity against K562 cells by a 51Cr release cytotoxicity assay. HNK-1+ cells were identified in gingival tissue sections of 21 patients, and were present in or close to discrete foci of plasma cells. HNK-1+ cells were scarce in mildly inflamed or uninflamed tissues sections. LGL were identified in 9 of 10 gingival single-cell suspensions and constituted approximately 5% of the gingival cell population. NK cell-mediated cytolysis, at varying effector/target cell ratios, was observed for 3 of 4 enriched gingival mononuclear cell populations. Gamma-interferon (INF-gamma) preincubation of enriched gingival effector cells from 5 additional patients resulted in a 43% increase in NK cell activity. The finding of increased HNK-1+ cells with gingival inflammation suggests that these cells may play a role in tissue damage, as well as in modulation of B cell activity, in gingivae of patients with periodontal disease.

Adult↗
PubMed1988

Secretory immune system of the female reproductive tract: I. Immunoglobulin and secretory component-containing cells.

We have investigated tissues from the female reproductive tract to determine whether the distribution of cells involved in the formation of secretory immunoglobulin A (IgA) molecules is analogous to that described for intestines, bronchus, and mammary and salivary glands. Fresh tissues from fallopian tube, ovary, uterus, and vagina were obtained, and sections were stained with fluorochrome-labeled polyclonal or monoclonal antibodies specific for IgG, IgA, IgA1, and IgA2 subclasses; IgM; secretory component; and J chain. Subepithelial plasma cells were identified in each specimen of fallopian tube, endocervix, ectocervix, and vagina. Approximately two-thirds of the immunoglobulin-positive cells contained IgA and J chain, indicating that they produced polymeric IgA. In comparison to tissues such as spleen and bone marrow, where IgA1-positive cells are produced, we found a high proportion of IgA2-positive cells in fallopian tube, cervix, and vagina. Epithelial cells in fallopian tube and endocervix contained secretory component. These data indicate that secretory IgA, which provides the first line of defense against invading pathogens, is produced locally in tissues of the female reproductive tract.

Antibodies, Monoclonal↗
PubMed1987

Normal human sera contain antibodies directed at Fab of IgA.

Serum samples from 26 normal volunteers were evaluated by isotype-specific ELISA for the presence of IgG and IgM antibodies directed at IgA. Although there were wide variations in antibody levels, anti-IgA antibodies of both isotypes were found in all individuals tested. The anti-IgA activity was detected against a variety of polymeric and monomeric IgA1 and IgA2 myeloma proteins containing both kappa and lambda light chains. By using Fab and Fc fragments generated by incubation of an IgA1 myeloma protein with IgA1 protease, it was shown that the anti-IgA activity was specific for the Fab portion of the IgA molecule. It was also demonstrated that the serum of two individuals contained both IgG and IgM activity directed at autologous affinity-purified IgA. IgM antibody levels against both whole IgA and Fab of IgA were significantly higher than IgG antibody levels. Cells producing anti-IgA antibodies of both isotypes were detected in lipopolysaccharide-stimulated human spleen.

Antibodies, Anti-Idiotypic↗
PubMed1987

Analysis of paraprotein transport into the saliva by using anti-idiotype antibodies.

To determine the extent of clonal involvement of the secretory immune system and the origin of salivary immunoglobulins (Ig) in monoclonal gammopathy patients, saliva and serum samples were collected from five affected individuals (two IgA myelomas, one IgG myeloma, one IgG benign monoclonal gammopathy, and one IgM lymphoma) and were assayed for the presence of monoclonal Ig. Purified polyclonal or monoclonal anti-idiotype (Id) antibodies were prepared against each of the isolated serum paraproteins. In all five individuals, the patient saliva samples inhibited the binding of 125I-labeled homologous Ig to the corresponding anti-Id antibodies, but normal saliva did not. The concentration of Id in patients' saliva varied from 1 to 400 micrograms/ml; i.e., 0.004 to 1.0% of the corresponding serum values. Saliva of a lymphoma patient whose IgM kappa protein exhibited rheumatoid factor (RF) activity also contained RF. The salivary Id-bearing molecules were found to have the same Ig isotype as the serum paraproteins. The myeloma IgA represented a minor component (0.4 and 3.9%) of the total salivary IgA. The salivary IgA myeloma proteins were associated at least in part with secretory component, but the salivary IgG paraproteins were not. In an IgA myeloma patient, a minority (17%) of the IgA+ plasma cells found in the lacrymal gland biopsy specimen were Id+, whereas the great majority (98%) of bone marrow IgA plasma cells were Id+. The results suggest active transport rather than passive transudation of myeloma IgA into the patients' saliva, and the integrity of the secretory immune system was not compromised by the neoplastic process.

Biological Transport↗