IgE and IgG epitope mapping by microarray peptide-immunoassay reveals the importance and diversity of the immune response to the IgG3 equine immunoglobulin.

The research article investigates the immune response to the IgG3 equine immunoglobulin, which can cause allergic reactions in patients when present as a contaminant in high purity snake antivenom treatments.

Objective of the Research

• The primary purpose of this research was to map the immunodominant IgE and IgG-binding epitopes in horse heavy chain IgG3 using arrays of overlapping peptides synthesized directly onto activated cellulose membranes. The aim was to understand the immune reaction better when patients are given snake antivenom treatment derived from horse IGG.

Methodology

• The team used microarray peptide-immunoassay, a technique that enables the synthesis of thousands of different peptides at once directly onto membranes, to map IgE and IgG epitopes.
• They used pooled human serum samples from patients with and without allergies to horse antivenom to probe the membrane.

Findings

• In both cases, it was revealed that people produce antibodies to epitopes of sequential amino acids of horse heavy chain IgG3.
• However, the signal strength and specificity seem to be distinct between patients with and without allergies to horse antivenom.
• A specific region was found to contain the dominant allergic IgE epitope.
• The critical residues involved in the binding of human IgE to the epitope were determined to be four hydrophobic amino acids followed by polar and charged residues that formed a coil structure.

Significance

• This is the first study that describes the specifics of amino acid sequences involved with the immune recognition of human IgG and IgE to horse antivenom. This could have potential implications for improving the safety and efficacy of snake antivenom treatments, reducing the risk of allergic reactions.