IgE structure-function relationships defined by sequence directed antibodies induced by synthetic peptides

Michael W. Robertson, Fu-Tong Liu

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Six peptides, representing contiguous amino acid sequences within the Cε{lunate}2, Cε{lunate}3 and Cε{lunate}4 domains ofmurine IgE, were selected for synthesis on the basis of overall hydropathy, degree of homology to both human and rat IgE and, where possible, inclusion of a native cysteine residue. Antibodies were produced against each peptide by immunizing rabbits with peptide-KLH conjugates. Each anti-peptide antiserum exhibited good reactivity with the corresponding immunizing peptide (titer: 10-4 to 10-5) and four of the six antisera exhibited a distinct preferential murine IgE reactivity compared to four other murine immunoglobulin classes (IgG1, IgG2b, IgM and IgA). In addition, one antiserum (anti-ε{lunate} peptide 5), raised against a peptide with 80% homology to human IgE, reacted comparably with both human and murine IgE. Each IgE-reactive antiserum was screened for the ability to stimulate mediator release from IgE-sensitized rat basophilic leukemia (RBL) cells. Two of the four IgE-reactive antisera strongly stimulated 3H-serotonin release (anti-ε{lunate} peptides 4 and 5), one antiserum showed weak activity (anti-ε{lunate} peptide 3) and the remaining anti-peptide serum (anti-ε{lunate} peptide 6), which exhibited the highest anti-IgE reactivity, exhibited no detectable stimulatory activity. Individual anti-peptide antibodies were subsequently tested for the potential to bind to receptor-bound IgE. Anti-ε{lunate} peptide 3 was shown to exhibit the least binding, anti-ε{lunate} peptide 6 showed the highest magnitude of binding while anti-ε{lunate} peptides 4 and 5 exhibited intermediate values. We conclude from this study that sequences defined by ε{lunate}-peptides 4 and 5 are not significantly involved in the receptor binding mechanism whereas ε{lunate} -peptide 3 is likely to be most proximal to the IgE-receptor recognition site of those sequences studied. Finally, we suggest that the ε{lunate}-peptide 6 sequence is in such an orientation in cell-bound IgE that, while it is accessible to external antibody, effective cross-linking of the IgE-receptor complex cannot be achieved through this determinant.

Original languageEnglish (US)
Pages (from-to)103-113
Number of pages11
JournalMolecular Immunology
Volume25
Issue number2
DOIs
StatePublished - 1988

ASJC Scopus subject areas

  • Molecular Biology
  • Immunology

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