Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have studied complement-mediated prevention of precipitation (PIP) and solubilization of immune complexes (IC) formed with DNP19-BSA and murine monoclonal antibodies (MCAs) of different isotypes and affinities. PIP was effective for IC formed with IgG1 and IgM antibodies, but not for IgA MCA. For IgG1 MCAs, affinity appeared to exert a minor effect on PIP, and IC formed in antibody excess or at equivalence were retained in solution more readily than those formed in antigen excess. For IgM MCAs affinity and antigen-antibody ratio did not affect PIP. As PIP did not occur in Mg-EGTA, it was concluded that PIP was entirely classical pathway dependent. Solubilization of IC containing IgG1 MCAs occurred more rapidly and to a greater extent with low affinity antibodies and an inverse relationship between affinity and the extent of solubilization was observed. Complexes formed with IgG1 MCAs were solubilized relatively poorly when formed in antigen excess. In contrast, affinity and antigen-antibody ratio did not influence the rate and extent of solubilization of IC containing IgM MCAs. IC formed with IgG2b were solubilized rapidly whereas those formed with IgG2a or IgA were solubilized poorly. The relative contributions of the classical and the alternative pathways to solubilization varied with each antibody and the effect of antigen-antibody ratio on these relative contributions was inconsistent.
Mol Immunol 1987 Nov
PMID:The effects of immunoglobulin isotype and antibody affinity on complement-mediated inhibition of immune precipitation and solubilization. 369 68

The processing and fate of mixed immune complexes is influenced by the antibody isotypes present. The hepatobiliary transport of mixed immune complexes containing the mouse IgA myeloma protein J558 and corresponding monoclonal IgG or IgM anti-J558 idiotype or monoclonal IgG anti-mouse IgA allotype antibodies has been studied. The anti-idiotype or anti-allotype antibodies were radiolabeled and injected into mice with or without mouse polymeric IgA (J558). IgG anti-idiotype antibodies to J558 IgA were selectively transported into bile by J558 IgA. This process occurred with a radiolabeled Fab preparation of the IgG anti-idiotype and was inhibitable with IgA of an irrelevant antigenic specificity. Thus, polymeric IgA influenced the fate of IgA-IgG idiotype-anti-idiotype serum immune complexes. A monoclonal anti-idiotype antibody of the IgM isotype (D8-3) was not selectively transported into bile by itself or as an IgA-IgM complex. A monoclonal IgG antibody (CB5-6) to a mouse allotype determinant in the Fc portion of IgA was not selectively transported into bile. This anti-allotype monoclonal antibody inhibited the hepatobiliary transport of 125I-polymeric J558 IgA and therefore appeared to directly or indirectly block the site in the Fc region of IgA recognized by the hepatic receptor.
Mol Immunol 1986 Mar
PMID:Analysis of the hepatobiliary transport of IgA with monoclonal anti-idiotype and anti-allotype antibodies. 371 9

Highly purified P. Zopfii galactan of mol. wt 2 X 10(5) binds monoclonal IgA J 539 with a Ka of 5.80 X 10(5) M-1 if the polysaccharide concn is expressed in blocks of 30 galactosyl residues. This is the same Ka as found for the antibody and methyl beta (1,6)-beta-D-galactopyranosyltetraoside, the ligand capable of filling the entire combining area of the immunoglobulin. This same polysaccharide precipitates monomeric IgA J 539 on agar-double diffusion. It is concluded that the antibody binds to intercatenary galactosyl residues of the antigen.
Mol Immunol 1986 Jun
PMID:Monoclonal anti-galactan IgA J 539 binds intercatenarily to its polysaccharide antigen. Observations on the binding of antibody to a macromolecular antigen. 374 15

The controversial issue of serum to milk transport of IgA in rodents was addressed in experiments that evaluated the molecular integrity and antigen-binding ability of the dimeric IgA (dIgA) recovered in the stomachs of rat and mouse pups suckling dams which had been administered homogeneous, dimeric M315 intravenously (i.v.). Four rat and three mice dams were i.v. administered affinity-purified, 125I-dIgA anti-DNP (M315) of which greater than 83% could bind DNP after iodination, and of which greater than 82% could be captured by solid phase anti-M315. Dams were given the labelled dIgA either 1-day or 8-days postpartum. Twenty-three hours after i.v. administration, the radioactivity of each pup, its stomach contents and an aliquot of serum were analyzed for total radioactivity, anti-DNP activity and for the molecular integrity of the recovered I-125. Data showed that 11-43% of 125I-activity given to the dam could be recovered from the stomach contents and sera of the pups after this time. Immunoassay revealed that less than 2% of the recovered radioactivity could bind DNP, i.e. a loss of 98% of functional antibody. It was calculated from ultracentrifugational analyses that less than 0.7% of the 125I-dIgA had been transported intact to the suckling neonates. Analyses of stomach milk and neonatal sera by sucrose density gradient ultracentrifugation revealed that almost all recovered radioactivity was in the form of low mol. wt fragments. Data fail to support the concept of an active mechanism for the transport of intact IgA from serum to milk in rodents during early or mid-lactation.
Mol Immunol 1986 Aug
PMID:Dimeric M315 is transported into mouse and rat milk in a degraded form. 379 27

IgA J539 is a monoclonal anti beta-(1----6)-D-galactopyranan. Measurement of its affinity with a number of synthetic galactosyl oligosaccharides of that linkage type, in which one or more hydroxyl groups have been replaced by a fluorine atom, confirm the assignment of the relative binding strength of the subsites in the protein for the individual galactosyl residues of the antigen.
Mol Immunol 1985 Jun
PMID:Probing the combining site of monoclonal IgA J539 using deoxyfluoro- and other galactosides as ligands. 383 64

Bacterial IgA1 proteases have substrate specificity for human IgA1 immunoglobulin, and cleave both the heavy (alpha) chains where they are paired by disulfide bonds in the hinge region. To determine if the close apposition of the alpha chains allows a single enzyme-substrate-binding event to cleave both hinge region peptides we quantitated the relative levels of intermediate products during the course of complete hydrolysis of an IgA1 paraprotein. The substrate had four Fab regions, analogous to a secretory IgA dimer. The experimental data were then compared to computer-generated models in which various levels of cooperativity among Fab regions were tested. The results most closely conformed to a model in which each individual alpha chain is proteolyzed independently, without regard to the total number of hinge region peptides available in the substrate IgA1. These results will be used to guide the design of IgA1 hinge region peptide analogues as IgA1 protease inhibitors.
Mol Immunol 1985 Jul
PMID:IgA1 protease cleaves heavy chains independently in dimeric human IgA1. 392 75

Examination of the gel electrophoresis patterns of 14C-biosynthetically labeled immunoglobulin from C57BL/6 X BALB/c IgA hybridomas reveals that each of the monoclonal cell populations produces two different forms of IgA: molecules with heavy chains (H) and light chains (L) joined by disulfide bonds, as well as molecules with H and L being noncovalently associated. The possible origin of this was explored: Southern blot analysis of the hybridoma DNA indicated that only one alpha gene is expressed by each cell line; hybridoma cells labeled in the presence of the N-glycosylation inhibitor tunicamycin exhibit both forms; and electrophoresis of biosynthetically labeled spleen cell IgA from C57BL/6, BALB/c and (C57BL/6 X BALB/c) F1 mice shows that BALB/c mice produce only the noncovalently associated form, while C57BL/6 and (C57BL/6 X BALB/c) F1 mice produce both. Possible mechanisms by which two types of IgA may be assembled by the same hybridoma cell are discussed.
Mol Immunol 1985 Dec
PMID:C57BL/6 x BALB/c hybridomas produce IgA which assembles into molecules with covalent bonds between heavy chains (H) and light chains (L), and into molecules lacking covalent bonds between H and L. 393 26

This paper describes the separation and characterization of several IgA fractions from the same human monoclonal source, based on their ability to bind secretory component (SC). The study was undertaken to elucidate features of the immunoglobulin-binding site for SC, and to examine the dependence of mucosal transport on IgA-SC interaction. Enrichment or depletion of SC-binding activity was accomplished on an affinity adsorbant made with SC from human colostral whey. The affinity-purified human IgA fractions contained IgA polymers and were 77% active in rebinding to the adsorbant; this activity was diminished significantly by direct radioiodination. The non-adherent IgA fractions contained both polymer and monomer, and were only 8% active in rebinding to the adsorbant. When the polymer and monomer components were separated from each other, the non-adherent polymer was found to resemble the affinity-purified fraction by all criteria examined including J-chain content, except that the SC-binding capacity was greater than five-fold lower. These findings have two implications for the SC-binding site on human IgA: first, the presence of J-chain is insufficient to bestow IgA with SC-binding activity; second, a critical tyrosine participates in maintaining the SC-binding region, possibly on the IgA heavy chain. The relationship between SC binding and mucosal transport was tested in the rat hepatobiliary model. All radiolabeled human IgA fractions were captured rapidly from blood by the rat liver, but only the SC-binding fractions underwent substantial intact transport to bile (greater than 70% of the injected dose). Even though a nominal proportion of the SC-non-adherent IgA appeared in bile (4-15% of the dose), most IgA in these fractions was rapidly degraded within the liver. Thus, only a small amount of monomeric and polymeric IgA can use alternative receptors to get to bile by diversion from the degradative pathway. Polymeric IgA can undergo efficient transport across the cell, strictly conditional on a high binding capacity for SC. This demonstrates that membrane SC is the receptor conferring specificity on the mucosal-transport pathway.
Mol Immunol 1986 Jan
PMID:Secretory component as the mucosal transport receptor: separation of physicochemically analogous human IgA fractions with different receptor-binding capacities. 396 32

An enzyme-linked immunosorbent assay (ELISA) has been developed to measure antibodies against pneumococcal polysaccharides of the IgA, IgG and IgM isotypes. Antibodies against pneumococcal polysaccharide types 1, 3, 6A, 8 and 9N were measured by ELISA and radioimmunoassay. Similar antibody responses were observed when comparing both assays. The study included 39 persons at high risk of developing pneumococcal infection and 13 healthy adults. Within 1 month after immunization IgM was the principle isotype. After 1 month, IgG was the principle isotype. Very low levels of IgA were detected in the post-immunization serum. The ELISA procedure described can be used to study the immune response to pneumococcal vaccines.
Mol Immunol 1985 Mar
PMID:Comparison of an enzyme-linked immunosorbent assay with radioimmunoassay for the measurement of pneumococcal capsular polysaccharide antibodies. 400 Jan 34

The distribution of cells with surface and cytoplasmic immunoglobulins was studied in Peyer's patches (PP) and intestine of rats, using both frozen and paraffin sections, with a two-step peroxidase technique. Anti IgM, IgG, IgA and IgE sera were used. Surface staining was found within PP with all antisera used. Although the villi contained predominantly IgA plasma cells (PC), IgG PC and a few IgM and IgE PC were also found. Within PP, however, no IgA PC were found but IgM and IgG PC were present in all stages of development, mainly in the dome. PC of all types, but mostly IgA cells, were present in and around high endothelial venules (HEV). The results suggest that IgM and IgG PC precursors can develop to PC within PP whereas IgA precursors do not. PC appear to home to the gut preferentially via HEV.
Virchows Arch B Cell Pathol Incl Mol Pathol 1982 Aug
PMID:An immunohistochemical study of cells with surface and cytoplasmic immunoglobulins in situ in Peyer's patches and lamina propria of rat small intestine. 612 34


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