Characterisation of the inflammatory reaction in equine idiopathic focal eosinophilic enteritis and diffuse eosinophilic enteritis

Authors

  • P. E. MAKINEN,

    1. Department of Veterinary Pathology, Faculty of Veterinary Science, University of Liverpool, Crown Street, Liverpool L69 7ZJ
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  • D. C. ARCHER,

    1. Department of Clinical Science, Faculty of Veterinary Science, University of Liverpool, Leahurst, Chester High Road, Neston, Cheshire CH64 7TE, UK
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  • K. E. BAPTISTE,

    1. Department of Large Animal Sciences, The Royal Veterinary and Agricultural University, Dyrlægevej 48, 1870 Frederiksberg C, Denmark.
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  • A. MALBON,

    1. Department of Veterinary Pathology, Faculty of Veterinary Science, University of Liverpool, Crown Street, Liverpool L69 7ZJ
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  • C. J. PROUDMAN,

    1. Department of Clinical Science, Faculty of Veterinary Science, University of Liverpool, Leahurst, Chester High Road, Neston, Cheshire CH64 7TE, UK
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  • A. KIPAR

    Corresponding author
    1. Department of Veterinary Pathology, Faculty of Veterinary Science, University of Liverpool, Crown Street, Liverpool L69 7ZJ
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Department of Veterinary Pathology, Faculty of Veterinary Science, University of Liverpool, Crown Street, Liverpool L69 7ZJ

Summary

Reasons for performing study: Idiopathic focal eosinophilic enteritis (IFEE) and diffuse eosinophilic enteritis (DEE) are primary eosinophilic intestinal conditions without a known cause that are associated with an increasing number of surgical colic cases. Histology may be helpful in defining disease aetiology and pathogenesis.

Objectives: To characterise further the inflammatory infiltrate in equine IFEE and to compare the condition with DEE.

Methods: Twenty-three IFEE cases and 5 DEE cases were examined by light microscopy including immunohistology to identify infiltrating leucocytes. Inflammatory infiltrates in mucosa and submucosa were characterised in IFEE lesions (Group 1), the intestine distant from the lesions in IFEE (Group 2) and DEE (Group 3).

Results and conclusions: IFEE lesions represented an accumulation of leucocytes in submucosa and muscularis, with dominance of eosinophils and macrophages and smaller numbers of lymphocytes, plasma cells and neutrophils. T cells represented the dominant lymphocytes. The mucosa overlying the lesion and both mucosa and submucosa in IFEE nonlesion sites and in DEE exhibited a similar composition, with different prevalence of various cell types. Macrophages were significantly more prevalent in the mucosal and submucosal infiltrates in IFEE nonlesion sites than in DEE, and lymphocytes significantly more prevalent in the mucosa in DEE than in IFEE nonlesion sites. The findings confirm IFEE as a primary eosinophilic intestinal disorder and indicate that IFEE represents a focally exacerbated inflammatory reaction in horses with DEE, possibly due to functional changes in the macrophage and T cell components, with subsequent excessive recruitment of both eosinophils and macrophages.

Potential relevance: This characterisation of the inflammatory reaction in IFEE and DEE represents the first comparative report on primary eosinophilic intestinal disorders in horses. It provides a starting point for more detailed investigations into the factors promoting these conditions.

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