Master of Science (MS)


Biomedical and Veterinary Medical Sciences - Veterinary Clinical Sciences

Document Type



ABSTRACT Objectives – To characterize the response of horse skin following intradermal injection of polyclonal rabbit anti-canine IgE (anti-IgE) and rabbit immunoglobulin G (IgG) in an attempt to develop a model of equine allergic skin disease. Study design - In vivo study. Animals – 10 Adult Thoroughbred horses. Methods –Horses were injected intradermally with one of two different concentrations of anti-IgE and rabbit immunoglobulin G (IgG). Wheal measurements and injection site biopsies were obtained before and 20 min, 6 hr, 24 hr, and 48 hr after injection. Tissue sections were stained with Hematoxylin and Eosin, Luna, and Toluidine Blue. Immunohistochemistry for CD3+, CD4+, and CD8+ cells was performed. Cells were counted in 1 mm2 of dermis and divided over four depths for standard stains: superficial dermal, superficial follicular, deep follicular, and deep follicular to adnexal. The superficial dermis was evaluated in immunohistochemistry sections. Results – Lower concentrations of anti-IgE produced suboptimal responses, so the higher concentration injections were evaluated. Anti-IgE wheals were significantly larger than IgG wheals at 20 min, 6 hr, and 24 hr after injection. Anti-IgE injected skin had significantly more degranulated mast cells than IgG injected skin and there were significantly more inflammatory cells (6 hr, 24 hr), eosinophils (6hr, 24hr, 48hr), and neutrophils (6 hr). Eosinophil counts significantly increased in anti-IgE samples in the deeper but not superficial dermis when compared to IgG samples. There were more eosinophils in the deeper dermis of anti-IgE injected skin. There were no significant differences between anti-IgE and IgG injected skin for CD3+, CD4+, or CD8+ cells. Conclusion - Injection of anti-IgE antibodies at a higher concentration was associated with the development of gross and microscopic inflammation that was characterized by mast cell degranulation and accumulation of inflammatory cells, particularly eosinophils and neutrophils. This pattern was similar to that seen in horses with spontaneous allergic skin disease, although lymphocytes were not increased. Clinical Relevance - This study documents the response to intradermal anti-IgE injection in horses and demonstrates the potential use of this model for studying equine allergic skin disease.



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Committee Chair

Andrews, Frank M