Reducing misclassification of monoclonal gammopathy in canine leishmaniosis: Added value of immunofixation to serum protein electrophoresis.

چکیده اصلی

Canine leishmaniosis caused by Leishmania infantum commonly induces marked dysproteinemia, yet restricted or apparently monoclonal gammopathies may complicate interpretation of serum protein electrophoresis (SPE). This study characterized SPE and immunofixation findings in 38 clinically sick dogs with confirmed canine leishmaniosis and evaluated interobserver agreement in gammopathy classification. SPE and immunofixation using anti-human reagents was performed on serum from 38 sick dogs with confirmed clinical leishmaniosis and without evidence of plasma cell neoplasia. The SPE data alone and a combined SPE and immunofixation (IF) study were interpreted by 4 reviewers. Inter-observer agreement for presence of an acute phase response and gammopathy pattern by electrophoresis alone or with immunofixation was assessed using Gwet's AC1 and quadratic weighted AC2. Change in agreement with addition of immunofixation was assessed. All dogs demonstrated hypergammaglobulinemia and decreased albumin-to-globulin ratios. Hyperproteinemia and hypoalbuminemia were common, and hyperbetaglobulinemia was frequently observed. Immunofixation labeling was predominantly IgG with minimal IgA and IgM detection. Most cases had an IgG polyclonal or restricted polyclonal gammopathy. Interobserver agreement for gammopathy classification using SPE alone was high (AC2 = 0.902), but disagreements spanned the diagnostic spectrum in some cases. The addition of immunofixation significantly improved agreement (AC2 = 0.944; P = 0.034) and reduced extreme interpretive divergence. No case was unanimously classified as monoclonal, and incorporation of immunofixation reduced suspicion for monoclonality in cases initially considered equivocal. Dogs clinically affected for canine leishmaniosis exhibit predominantly IgG-driven polyclonal hypergammaglobulinemia. Together, SPE and IF provide a more complete characterization of gammopathy patterns in dogs with leishmaniosis, particularly when SPE reveals restricted or monoclonal-like abnormalities that could otherwise raise concern for plasma cell neoplasia.

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