IgE Trimers Drive SPE-7 Cytokinergic Activity

Area of Science:

• Immunology
• Allergy Research
• Cellular Signaling

Background:

• Mast cells and basophils release allergic response agents upon antigen-induced cross-linking of receptor-bound IgE antibodies.
• A commercial monoclonal IgE antibody (SPE-7 IgE) exhibits unusual "cytokinergic" activity, inducing basophil degranulation without antigen presence.

Purpose of the Study:

• To identify the source of the anomalous cytokinergic activity in SPE-7 IgE.
• To elucidate the mechanism by which this activity is mediated.

Main Methods:

• Purification of IgE monomer to remove contaminants.
• Analysis of purified IgE and trace impurities.
• Investigating the interaction of IgE variants with basophil receptors.

Main Results:

• The purified IgE monomer lacks the cytokinergic activity.
• A trace impurity, identified as a stable IgE trimer, was responsible for the observed basophil degranulation.
• IgE trimers can induce degranulation independently of antigen binding.

Conclusions:

• The anomalous "cytokinergic" activity of SPE-7 IgE is attributed to a dissociation-resistant IgE trimer impurity.
• IgE trimers can directly trigger basophil degranulation, suggesting a novel pathway for allergic responses.
• Proposed models for IgE trimer formation and receptor cross-linking are presented.