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B Diamond

Publications and source records attributed to B Diamond.

At least 145 records · Page 8Linked to original sources
PubMed1985

Use of anti-idiotypic antibodies to identify a receptor for the T-cell I-J determinant.

In order to identify the molecule(s) interacting with the I-J determinant on suppressor T cells, we have generated two anti-idiotypic sera: one to monoclonal anti-I-Jd antibody and one to monoclonal anti-I-Jk antibody. These antisera specifically block suppressor T-cell function in a genetically restricted manner and have no effect on helper T-cell activation. Both recognize a marker on primary monocytes and B cells but not on T cells. A myeloma cell line bearing this marker has been identified. Therefore, these antisera may recognize a molecule on cells interacting with suppressor T cells that is involved in mediating suppressor T-cell activity. The relationship between the T-cell I-J determinant and the molecule identified by the anti-idiotype may be similar to the relationship between the receptor on helper T cells and Ia molecules.

Animals↗
PubMed1985

Familial systemic lupus erythematosus. Presence of a cross-reactive idiotype in healthy family members.

Sera of 27 members of 3 human kindreds with familial systemic lupus erythematosus (SLE) were examined for expression of a cross-reactive idiotype present on anti-DNA antibodies of SLE patients. By radioimmunoassay, serum samples from 6 of 8 SLE patients and 15 of 19 family members had high-titered reactivity with the antiidiotype, 3I. Isoelectric focusing and Western blot analysis of 3I-reactive bands revealed two patterns of reactivity: either a pattern of bands present at pH 5-7, or bands present at pH 5-7 with additional bands present at pH 7-8.5. Cationic bands were found to correlate with the presence of anti-DNA antibodies, indicating that immunoglobulin charge may be a factor in determining specificity for DNA. Millipore filter analysis revealed anti-DNA antibodies in sera of 4 of 8 SLE patients and 2 of 19 family members without SLE. In 2 additional SLE patients and 2 additional family members, anti-DNA antibodies were revealed when sera were analyzed under conditions that dissociate immune complexes. This study indicates that expression of an idiotype associated with anti-DNA antibodies is significantly increased in relatives of SLE patients and usually occurs in the absence of anti-DNA activity.

Antibodies, Antinuclear↗
PubMed1985

Site of binding of IgG2b and IgG2a by mouse macrophage Fc receptors by using cyanogen bromide fragments.

Cyanogen bromide fragments of murine IgG2b and IgG2a immunoglobulins were used to localize the sequences that are bound by specific IgG2b and IgG2a Fc receptors on murine macrophages. One fragment from the CH2 domain of IgG2b bound to the gamma 2b Fc receptor. Two fragments from IgG2a--one one from the CH2 domain, differing by only four amino acids from the homologous IgG2b fragment, and the other from the CH3 domain--specifically bound to the gamma 2a Fc receptor. In both a rosetting assay and a radioactive binding assay, these two fragments from IgG2a competed with intact IgG2a: however, they did not compete with each other. Rather, binding of the fragment from the CH3 domain of IgG2a augmented the binding of the fragment from the CH2 domain of IgG2a but not that of the homologous fragment from IgG2b. The binding of both IgG2a fragments was abolished by trypsin treatment of macrophages. These data suggest that 1) a sequence in the CH2 domain of IgG2b is sufficient for binding to the gamma 2b Fc receptor, 2) sequences from both the CH2 and CH3 domains of IgG2a bind to the gamma 2a Fc receptor, and 3) the binding of sequences from the CH3 domain of IgG2a may induce a conformational change in the gamma 2a Fc receptor that leads to enhanced binding of sequences from the CH2 domain.

Animals↗
PubMed1985

Fc receptors on cultured myeloma and hybridoma cells.

The specificity of the Fc gamma receptors on the X63.Ag8.653 nonproducing myeloma cell line has been examined for binding to IgG1-, IgG2a-, and IgG2b-containing antigen-antibody complexes. Complexes containing each of these subclasses bind, and the binding of each is inhibited by the others. Trypsin treatment did not inhibit the binding of any of these subclasses. Furthermore, the monoclonal anti-Fc receptor antibody 2.4G2 inhibits the binding of all three subclasses. These results, together with those of other investigators, suggest that there is a single FcR for IgG1, IgG2a, and IgG2b on mouse B cells which differs in its specificity from the macrophage Fc gamma R. This is confirmed by the fact that a mutant IgG2b myeloma protein which binds to the macrophage Fc gamma 1/gamma 2b receptor does not bind to the Fc gamma R on X63.Ag8.653.

Animals↗
PubMed1985

Generation of functional I-Ed variants from an antigen-presenting macrophage cell line.

We report the ability of the BAC1.2 macrophage cell line to present antigen both to populations of antigen-primed lymph node cells and to T cell hybridomas. We also describe the selection of I-Ed variants derived from this cell line. These variants have lost the ability to present antigen to an I-Ed plus ovalbumin-specific T cell line, but retain the ability to stimulate an I-Ad plus ovalbumin-restricted T cell line, and a T cell line reactive with I-Ed alone. These variants should aid in the elucidation of structural elements of the I-E molecule involved in the interaction with helper T cells.

Animals↗
PubMed1984

Somatic mutation of the T15 heavy chain gives rise to an antibody with autoantibody specificity.

The S107 IgA kappa-chain myeloma cell line makes an antiphosphocholine antibody of the T15 idiotype. A somatic mutant of this line, U4, makes an immunoglobulin with a single amino acid substitution of an alanine for a glutamic acid at residue 35. This single amino acid change results in a loss of phosphocholine binding activity. However, the U4 immunoglobulin has acquired reactivity with a variety of phosphorylated macromolecules, including double-stranded DNA, protamine, and cardiolipin. Thus, a single amino acid change in the T15 heavy chain can transform an antibacterial antibody into an antibody that resembles the autoantibodies seen in mice and man with autoimmune disease.

Animals↗
PubMed1984

The generation of macrophage-like cell lines by transfection with SV40 origin defective DNA.

Two cell lines with properties of mature macrophages have been generated by transfection with SV40 DNA mutated in the origin of replication. One line, BAM, was derived from bone marrow cells from a BALB/c mouse. The other line, BAC1, was derived from splenic adherent cells from a (BALB/c X A.CA) F1 mouse. Both lines produce lysozyme, collagenase, and esterase, bear Fc receptors, and engage in Fc-mediated phagocytosis. Both lines require colony-stimulating factor-1 for continued proliferation. In addition, they express Ia antigens, and may be induced to secrete IL 1. This technique should make possible the generation of Ia-bearing diploid macrophage lines from any strain of mouse. In addition, it may be possible to use this technique to derive monocyte lines from species in which wild-type SV40 DNA causes a lytic infection.

Animals↗
PubMed1984

Detection of masked anti-DNA antibodies in lupus sera by a monoclonal anti-idiotype.

We report here the use of a monoclonal anti-idiotype 3I to human anti-DNA antibodies to detect in serum idiotype-positive antigen-binding antibodies lacking DNA-binding activity as measured by conventional antigen binding assays. We studied paired serum samples from 13 patients with systemic lupus obtained at two times in the course of their disease: in each patient, one serum sample has anti-DNA activity and the second serum sample has no anti-dsDNA activity detectable by Millipore filter, ELISA, or Crithidia assay. Reactivity with 3I as detected with a radioimmunoassay (RIA) was present in all 13 sera with anti-dsDNA activity. Six patients showed a decrease in 3I reactivity to normal levels in the second serum sample, in which anti-dsDNA antibodies were not detectable by conventional antigen-binding assays. The other seven patients' second serum sample continued to show elevated 3I reactivity by RIA even though no anti-dsDNA activity was apparent. When the 3I-reactive antibodies from these latter patients' sera were eluted from a 3I affinity column, they revealed DNA-binding activity. Furthermore, dsDNA binding by these sera was apparent when they were displayed on Western blots of isoelectric focusing gels run in 8 M urea and incubated with radiolabeled dsDNA. These results indicate that the 3I anti-idiotype can detect anti-DNA antibodies in some sera of SLE patients that lack anti-DNA activity by ordinary assays. These antibodies may be inhibited in binding dsDNA by excess antigen or autologous anti-idiotype, and their DNA binding activity can be unmasked by procedures promoting immune complex dissociation.

Antibodies, Anti-Idiotypic↗
PubMed1983

Use of monoclonal antibodies to identify shared idiotypes on human antibodies to native DNA from patients with systemic lupus erythematosus.

Antinative DNA antibodies were purified from the serum of a patient with active systemic lupus erythematosus. Using hybridoma technology, we produced several mouse monoclonal antibodies directed against idiotypic determinants on these antinative DNA antibodies. One of these monoclonal anti-idiotypic antibodies, 3I, an IgG2a Kappa, was extensively characterized. 3I is believed to be directed against an idiotypic determinant because (i) its reactivity with antinative DNA antibodies is not inhibited by a large excess of pooled human serum, (ii) it reacts with F(ab')2 fragments of antinative DNA antibodies, and (iii) it reacts with antinative DNA antibodies of all IgG subclasses. 3I is not directed against the antigen binding site in that native DNA and 3I do not compete for binding to antinative DNA antibodies. Eight of nine sera containing antinative DNA activity as determined by the Millipore filter assay reacted with 3I in a solid-phase radioimmunoassay. These findings suggest that antinative DNA antibodies from nonrelated patients with systemic lupus erythematosus share a common idiotype.

Antibodies, Anti-Idiotypic↗
PubMed1983

The J744.2 cell line presents antigen in an I region restricted manner.

We report here the ability of a murine macrophage-like cell line, J774.2, to present antigen to primed T cells in a genetically restricted manner. J774.2 is a subclone derived from the reticulum cell sarcoma cell line, J774. Like mature macrophages, J774.2 possesses Fc receptors for all immunoglobulin G (IgG) subclasses; it is capable of performing Fc-mediated phagocytosis, and it secretes both lysozyme and plasminogen activator.

Animals↗
PubMed1982

Effects of immunoglobulin structure on Fc receptor binding: a mouse myeloma variant immunoglobulin with a gamma 2b-gamma 2a hybrid heavy chain having a complete gamma 2a Fc region fails to bind to gamma 2a Fc receptors on mouse macrophages.

We report here the primary structure of an immunoglobulin heavy chain synthesized by ICR 16, a variant of the MPC 11 mouse myeloma cell line. The ICR 16 heavy chain is a gamma 2b-gamma 2a hybrid, consisting of the CH1 domain of gamma 2b and the hinge, CH2 and CH3 domains of gamma 2a subclasses. The genetic mechanism by which ICR 16 occurred may be recombination, based on homologies in both coding and intervening sequences in gamma 2b and gamma 2a constant region genes. Although the Fc fragment of ICR 16 is completely gamma 2a-like and has been shown to bind to gamma 2a Fc receptors on mouse macrophages, the intact H2L2 molecules is unable to do so. Such an observation underscores the crucial role that conformation may play in the ability of immunoglobulins to carry out biologic functions.

Amino Acid Sequence↗
PubMed1981

A new Fc receptor on mouse macrophages binding IgG3.

Monoclonal antibodies to sheep erythrocytes (SRBC) have proved useful in identifying two Fc receptors on mouse macrophages, one for IgG2a, and one for IgG1 and IgG2b. We have used monoclonal IgG3 anti-SRBC to identify a third Fc receptor on mouse macrophages which binds IgG3 uniquely. This receptor is present on primary resident and thioglycolate-induced peritoneal macrophages and on some macrophage cell lines. The binding of IgG3-coated SRBC is inhibited by aggregated byt not monomeric IgG3, and not by IgG1, IgG2a, and IgG2b aggregates. It is unaffected by treating the macrophages with trypsin or cytochalasin B and occurs at both 4 degrees and 37 degrees C. IgG3, like all other IgG subclasses, mediates phagocytosis. We have also generated a variant macrophage line which bears the receptors for IgG1 and IgG2b and for IgG2a, but not for IgG3.

Animals↗