Expression of a 4-(hydroxy-3-nitro-phenyl) acetyl (NP) specific equi-murine IgE antibody that mediates histamine release in vitro and a type I skin reaction in vivo.

This research article details the production of a stable cell line that can be used to understand how a specific type of immunoglobulin (IgE) functions in allergic disease in horses.

Objective of the Study

• The aim of the study was to create a stable cell line that expresses a specific type of equi-murine IgE specific for 4-(hydroxy-3-nitro-phenyl) acetyl (NP), with an intention to investigate IgE-mediated mechanisms in horses which may contribute to enhancing our understanding of allergic diseases in these animals.

Problem Addressed

• Allergic diseases in horses are believed to be linked to immunoglobulins of isotype E (IgE). However, further studies have been limited in part due to the unavailability of purified equine IgE or anti-equine IgE monoclonal antibodies that can help in IgE isotype determination.

Method and Approach

• The researchers created a stable cell line, EqE6, which expresses a specific recombinant equi-murine IgE for 4-(hydroxy-3-nitro-phenyl) acetyl (NP).
• The biochemical analysis of the purified protein showed a highly glycosylated IgE monomer approximately weighing 230,000 Da.
• An in vitro model which used equine blood leukocytes was utilized to examine the ability of NP-IgE to mediate histamine release post crosslinking with the antigen.
• An in vivo model, involving the intradermal application of NP-IgE followed by antigen crosslinking, was carried out to induce a type I hypersensitivity skin reaction in horses.

Findings

• The in vitro and in vivo experiments demonstrated that the recombinant NP-IgE contains a functional Fc(epsilon) RI binding site. This property allows it to mediate effector functions in equine basophils and mast cells, which play an essential role in triggering an allergic response.
• The findings suggest that the equi-murine IgE can be used for creating IgE-specific polyclonal and monoclonal antibodies. It can also aid in antigen-specific activation of equine Fc(epsilon)-receptor-expressing cells such as mast cells and basophils.

Impact and Conclusion

• The findings enable the possibility of more in-depth research into IgE-mediated mechanisms related to allergic diseases in horses. They pave the way for developing better understanding and potentially improved treatments for equine type I allergic diseases.