Evaluation of Immune System Components in Dogs With Protein-Losing Enteropathy Compared to Healthy Controls

Background

Immune system abnormalities including hypogammaglobulinemia and T-cell deficiency occur in humans with protein-losing enteropathy (PLE). It is unknown whether similar abnormalities occur in dogs with PLE.

Objective

To evaluate serum immunoglobulin (Ig) concentrations and immune cell populations in dogs with PLE (with histologic evidence of chronic inflammatory enteropathy, intestinal lymphangiectasia (IL), or both) compared to healthy controls (HC).

Animals

Eighteen dogs with PLE and 18 HC dogs.

Methods

Prospective study. Serum IgA, IgG, and IgM concentrations were measured via ELISA in treatment-naïve dogs with PLE and compared to concentrations in HC dogs. RNA gene expression of specific immune cell surface markers in peripheral blood mononuclear cells (PBMCs) was measured in both groups by quantitative PCR.

Results

Dogs with PLE had lower concentrations of serum IgG compared to HC dogs (4.5 mg/mL, range 0.67–22.4 mg/mL vs. 19 mg/mL, range 1.8–80.3 mg/mL; p < 0.001). Serum IgM concentrations were also lower in dogs with PLE versus HC (2.4 mg/mL, range 0.0009–53.1 mg/mL vs. 14.2 mg/mL, range 2.1–172.8 mg/mL; p = 0.002). Expression of CD3e (0.24, range 0.003–1.1 vs. 0.92, range 0.41–3.2; p < 0.001), CD5 (0.17, range 0.01–0.46 vs. 0.94, range 0.23–5; p < 0.001), and CD8 (0.47, range 0.06–1.7 vs. 0.92, range 0.32–2.4; p = 0.007) were reduced in dogs with PLE compared to their mean absolute expression in HC dogs.

Conclusions and Clinical Importance

Dogs with PLE have quantitative reductions in immune system components, similar to humans with IL. These abnormalities in immune system components might be considered in the management and monitoring of dogs with PLE.