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Biomedical subjects

D R Stanworth

Publications and source records attributed to D R Stanworth.

At least 37 records · Page 2Linked to original sources
PubMed1989

Anti-viral antibodies in HIV (HTLV-III) infection possess auto-antibody activity against a CH1 domain determinant in human IgG: possible immunological consequences.

Two regions of the envelope glycoprotein gp120 of the human immunodeficiency virus were shown to have a significant degree of homology to human immunoglobulin-gamma heavy-chain constant domains. We have now synthesized three short linear peptides, the first representing a sequence within the CH1 domain, the second an analogue of it, and the third representative of a region within the viral gp120. Polyclonal antibodies against these peptides were raised in rabbits and used to demonstrate that they all reacted well with human native IgG. Vice-versa, we observed the reaction of these antisera to the virus in an ELISA system. The proportion of sera reacting with the human gamma-chain peptide was significantly higher in HIV-positive individuals than in HIV-negative individuals, suggesting production of anti-viral antibodies in AIDS patients with auto-antibody activity against a CH1 domain determinant in human IgG.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Sulphasalazine therapy in ankylosing spondylitis: its effect on disease activity, immunoglobulin A and the complex immunoglobulin A-alpha-1-antitrypsin.

Serum levels of immunoglobulin A (IgA) and the complex immunoglobulin A-alpha 1 antitrypsin (IgA-alpha 1AT) were measured at the commencement and after 3 months of a double-blind, placebo-controlled trial of sulphasalazine (SAS) in patients with active ankylosing spondylitis (AS). Twenty-eight patients were evaluated, 15 on sulphasalazine, 13 on placebo. Significant falls were seen in both IgA (p less than 0.01) and IgA-alpha 1AT (p less than 0.001) in the actively treated patients. In addition, significant improvement in clinical and laboratory measures of disease were observed. It is concluded that SAS is effective in AS and modulates the immune response.

Adult↗
PubMed1989

The incidence of IgE and IgG antibodies to chlorhexidine.

IgE antibodies to the antiseptic agent chlorhexidine have recently been detected in the majority of sera from a small group of predominantly Japanese individuals showing anaphylactic-type adverse reactions towards chlorhexidine. In this study the prevalence of IgE and IgG antibodies with specificity for chlorhexidine was investigated in groups of Japanese and British individuals. The RAST data, using a better defined semi-chlorhexidine-HSA antigen than previously employed, revealed that chlorhexidine-specific IgE was only detected in Japanese individuals who had experienced anaphylactic-type reactions and was not detected in groups of Japanese nurses and patients, or in groups of British nurses and hospital staff, all in regular contact with chlorhexidine. A group of British blood donors was also negative. In contrast, IgG antibodies were detected not only in sera from chlorhexidine-sensitive Japanese patients, but also in several sera from Japanese nurses, non-sensitive Japanese patients and several British individuals. The possible reasons for these observations are discussed.

Adult↗
PubMed1989

IgA-alpha 1 antitrypsin complexes in ankylosing spondylitis.

A study of 95 serum samples from 61 patients with ankylosing spondylitis (AS) showed that 21 patients (34%) had raised levels of IgA-alpha 1 antitrypsin complexes. These were associated with active disease as measured by a clinical index and also with erythrocyte sedimentation rate, C reactive protein, and serum IgA. In particular, an association was noted between 'extraspinal' manifestations of AS such as synovitis, uveitis, and active inflammatory properties of these complexes. It is suggested that these complexes may have a role in the pathogenesis of such clinical manifestations.

Adult↗
PubMed1988

Synergistic enhancement of histamine release from rat peritoneal mast cells by the phorbol ester 12-O-tetradecanoylphorbol 13-acetate is not reflected by corresponding changes in phospholipid turnover.

In an attempt to elucidate further the relationship between changes in phospholipid metabolism in, and histamine secretion from, purified rat peritoneal mast cells, the effects of the phorbol diester 12-O-tetradecanoylphorbol 13-acetate (TPA) on these responses in stimulated and unstimulated cells was investigated. TPA caused a dose-dependent increase in the incorporation of 32PO4(3-) into the mast cell phospholipids; phosphatidic acid (PA) and phosphatidylcholine (PC), but not phosphatidylinositol (PI). TPA synergistically enhanced histamine release from cells stimulated by anti-immunoglobulin E (IgE) and the calcium ionophore A23187, reducing its ED50 from 150 nM to 40 nM, but did not alter histamine release from cells stimulated by compound 48/80. The effect of TPA on the changes in 32PO4(3-) incorporation into phospholipids associated with the above secretagogues did not, however, correlate well with the observed effects on histamine secretion induced by the same secretagogues. These observations are discussed in relation to the known effects of phorbol esters upon both secretory processes and phospholipid metabolism in other tissues.

Animals↗
PubMed1988

The effect of synthetic peptides corresponding to Fc sequences in human IgG1 on various steps in the B cell activation pathway.

The influence of synthetic peptides comprising sequences in the exposed positions of the Fc region of human IgG 1 was tested on B lymphocyte activation. CH 2 domain peptides having an inhibitory effect on antibody-dependent cellular cytotoxicity, as well as the whole Fc fragment, induced the appearance of the early signs of activation on resting B lymphocytes such as increase in cell volume and HLA-DR antigen expression or leukocyte migration inhibitory factor production. The peptides did not induce proliferation of resting B cells even when B cell growth factor (BCGF)-containing supernatants were added. Exposure to Fc fragment, however, induced a weak proliferation which was significantly enhanced by BCGF. On the other hand, both the Fc fragment and the CH 2 or CH 3 domain peptides enhanced the IgM synthesis of human blood mononuclear cells when a suboptimal dose of pokeweed mitogen was present. This effect was lost when Fc fragment or the peptides were added on the third day of culture. These results suggest that the early steps of B cell activation can be induced by Fc fragment and by small molecular weight Fc peptides, which are potential ligands of Fc receptors. The Fc fragment activates B cells to the state where they respond to BCGF, but the peptides do not possess this activity. Furthermore, both Fc fragment and Fc peptides are able to enhance the IgM synthesis, when accessory cells and the appropriate differentiating factors are present.

Amino Acid Sequence↗
PubMed1988

Immunomodulatory effect of synthetic peptides corresponding to sequences within the CH2 and CH3 domain of human IgG1.

The Fc region of IgG is known to be the source of small peptides possessing immunomodulatory function. Results are summarized showing the effect of synthetic peptides composed of surface exposed residues of C gamma 2 or C gamma 3 domains on different steps of human B lymphocyte activation cycle. Both the CH2 (289Thr-301Arg) and CH3 (407Tyr-416Arg) peptides as well as the whole Fc fragment enhanced the IgM synthesis of PWM or PMA + CaI activated lymphocytes. This effect was exerted at the early phase of B cell activation. The incubation of separated resting B cells with Fc fragments or CH2 peptides resulted in increase of cell volume and in expression of HLA-DR antigen. On the other hand, LIF production was induced both by CH2 and CH3 peptides. It was also shown that Fc peptides induce IL-1 release from monocytes. The results suggest that the CH2 and CH3 domain peptides exert their effect partly directly, by activating resting B cells, rendering the cells more susceptible to other stimuli; and moreover, by enhancing the humoral response by triggering the release of IL-1.

B-Lymphocytes↗
PubMed1988

Inter-receptor relationships in effector cell triggering, with particular reference to the mast cell.

The role of IgE antibodies in the initiation of allergen induced release of mediators from sensitised mast cells is discussed; both from the point of view of their binding to the high affinity Fc(epsilon)RI receptor and in their provision of a triggering signal, resultant upon the cross-linking of cell bound IgE molecules by specific antigen (allergen). A possible inter-relationship between the Fc(epsilon)RI and a low affinity receptor for the IgG4 isotype on human mast cells is considered, in the light of evidence that the two types of receptor could be acting synergistically in certain clinical allergy situations (e.g. atopic eczema). It is suggested that a similar juxta-positioning of Fc(gamma 4)RII and Fc(epsilon)RI receptors on human B-lymphocytes might provide scope for regulation of IgE synthesis by IgG4 auto-antibodies directed against this immunoglobulin isotype.

Antigens, Differentiation↗
PubMed1988

A monoclonal antibody raised against a synthetic peptide representative of part of the amino acid sequence of rat immunoglobulin E detects thermally induced changes in that region of the IgE molecule.

A mouse monoclonal antibody (mAb) has been produced by conventional cell fusion methods against a synthetic peptide, p123, representative of a portion of the CH4 domain of rat immunoglobulin E (IgE). This monoclonal antibody was reactive with both peptide and purified rat IgE (p.rat IgE) by indirect enzyme immunosorbent assay (ELISA), and its binding to p.rat IgE was found to be inhibitable by pre-incubation with rat ascitic fluid containing the immunocytoma 162 (IR162) IgE. Heating of the immunocytoma IgE in solution at 56 degrees for 1 hr resulted in its enhanced binding of the mAb. The effect of this treatment was investigated further using p.rat IgE heated at 56 degrees for various time intervals between 0 and 60 min. The mAb showed enhanced binding to IgE heated for as little as 10 min, a similar level of binding being shown by samples heated for 30 and 60 min. The degree of aggregation of the IgE molecules brought about by the heat treatments was measured by differential UV absorption. This revealed a decrease in the proportion of monomeric IgE with an accompanying increase in the percentage of dimer and larger aggregates with increased time of heating at 56 degrees. These absorption data, together with the ELISA inhibition data, suggest that, rather than inducing changes mediated by aggregation of the IgE molecules in solution, heating at 56 degrees causes subtle alterations in the conformation of individual IgE molecules at specific sites within their CH4 domains, one of which is detected by this mAb.

Amino Acid Sequence↗
PubMed1987

Inhibition of binding of rat IgE to rat mast cells by synthetic IgE peptides.

Seven synthetic peptides corresponding to amino acid sequences located within various surface regions of the CH3 and CH4 domains of rat IgE were tested for their capacity to compete with intact rat IgE for binding sites on mast cells. Peptides representing rat IgE sequences 414-428 (P129), 459-472 (P124), 491-503 (P128) and 542-557 (P123) inhibited the binding of 125I-labeled rat IgE to mast cells by between 25-50% at concentrations between 10(-5)-10(-4) M. Three other rat IgE sequences, 378-396 (P130), 522-535 (P122) and 560-571 (P131), and three non-IgE peptides demonstrated no inhibitory activity. On a molar basis, the most active peptide, P129, was approximately 1000-times less active than native rat IgE. Furthermore, extensive washing of cells incubated with this peptide did not reduce its ability to inhibit the subsequent binding of 125I-labeled rat IgE. These results suggest that residues within sequences 414-428, 459-473, 491-503 and 542-557 may contribute towards the mast cell receptor binding site on rat IgE.

Amino Acid Sequence↗
PubMed1987

Regulation of human natural cytotoxicity by IgG--I. Characterization of the structural site on monomeric IgG responsible for inhibiting natural killer cell activity.

Inhibition of human natural killer (NK) cell activity upon exposure of peripheral blood lymphocytes (PBL) to IgG in monomeric form (mIgG) was found to be dose-, time- and temp-dependent. PBL incubated for 2 hr at 37 degrees C in the presence of myeloma protein of a certain class or subclass had a significant reduction of their NK activity when exposed to IgG, but not to IgM or IgD, and the IgG-induced inhibition of NK cells was observed only when IgG1 or IgG3 paraproteins were used. IgG3 isolated from normal serum had a higher inhibitory property than that of total mIgG. The cytophilic activity of the IgG molecules was confined entirely to the Fc region and seemed to be localized in the CH3 domain, since human and rabbit Facb fragments had a reduced ability to inhibit NK activity. When synthetic peptides representing various sequences of the human gamma-chain were tested for inhibition of NK activity, only treatment of effector cells with a peptide comprising the sequence Tyr407-Arg416 of the CH3 domain showed a reduction of NK cell function comparable to the inhibition obtained following incubation of cells in the presence of mIgG. However, on a molar basis, this peptide was 20 times less active than mIgG. In contrast, peptides derived from sequences in the CH2 domain lacked this inhibitory capacity. Our data indicate that the structural site responsible for inhibiting NK cell activity is located in the C-terminal domain of the IgG molecule.

Amino Acid Sequence↗
PubMed1987

Factors influencing the immunogenicity of the haptenic drug chlorhexidine in mice--Part I. Molecular requirements for the induction of IgE and IgG anti-hapten antibodies.

The immunogenicity of a novel hapten, the anti-microbial agent, chlorhexidine (1,1'-hexamethylene bis [5-(p-chlorophenyl)biguanide]) was assessed in mice, using alum as adjuvant. The i.p. injection of electrostatically-linked chlorhexidine + keyhole limpet haemocyanin (KLH) mixtures induced low level primary IgG anti-chlorhexidine antibody synthesis. In contrast, covalently-linked chlorhexidine-KLH complexes induced both IgE and IgG anti-chlorhexidine antibody synthesis. Covalent binding was facilitated by the N-chlorination of secondary amide groups on the biguanide moeities of the chlorhexidine molecule. The immunogenicity of such complexes was related to the degree of conjugation of chlorhexidine to KLH; which, in turn, was related to the molarity of chlorine used to effect N-chlorination. Immune responses to covalently-linked complexes could be enhanced by carrier priming. The induction of low levels of IgG anti-hapten antibodies by electrostatically-linked complexes may reflect T cell-independent specific B cell activation, either by chlorhexidine itself or by a "pseudo-plurivalent" chlorhexidine + KLH antigen.

Animals↗
PubMed1987

Analysis of the interaction between rat immunoglobulin E and rat mast cells using anti-peptide antibodies.

Polyclonal antisera with pre-determined specificities for a range of rat IgE epitopes were produced by immunizing rabbits with KLH-conjugates of five different synthetic peptides representing sequences 378-396, 414-428, 491-503, 522-535 and 560-571 in the CH3 and CH4 domains of rat IgE. Each rabbit elicited peptide-specific antibodies which were capable of binding affinity-purified rat IgE (IR162) (titres 1/1000-1/10,000) and IgE in rat immunocytoma serum (IR162) either immobilized on microtitre-plates or in free-solution as assessed by ELISA. Heating a solution of rat IgE at 56 degrees C for 1 hr, a treatment known to abolish the cytophilic activity of rat IgE and also induce irreversible conformational changes in the CH3 and CH4 domains, resulted in enhanced binding of the immunoglobulin to antibodies directed against IgE sequences represented by two of the synthetic peptides 414-428 and 491-503, but not to the three other peptides. The five anti-peptide sera together with two previously studied antisera specific for rat IgE sequences 459-472 and 542-557 were tested in functional assays designed to investigate the mode of interaction between rat IgE and its receptor on rat mast cells. Each anti-peptide serum was capable of inhibiting the binding of IgE to mast cells and furthermore, able to initiate the secretion of histamine from cells sensitized with rat IgE in an "anti-IgE"-induced manner. In view of the evidence implicating the CH3 and/or CH4 domains as the location of the mast cell receptor-site on rat IgE, we propose a model to describe the mode of interaction between IgE and its mast cell receptor.

Amino Acids↗