Evaluation of serum protein electrophoresis and immunofixation in dogs seropositive for various vector-borne pathogens

Abstract

Background: Canine vector-borne diseases (VBDs) induce non-specific dysproteinemias, detectable by serum protein electrophoresis (SPE). VBDs have been reported to induce a monoclonal gammopathy pattern. Monoclonal gammopathies are commonly the result of paraprotein (M-protein) produced by an immunoglobulin-secreting neoplasm.

Objectives: The aims of this study were to characterize and compare SPE and immunofixation (IF) changes, evaluate the performance of previously identified SPE and IF interpretative criteria, and identify M-proteins in a cohort of dogs seropositive for a VBD and with an unknown history for an immunoglobulin-secreting neoplasm.

Methods: A total of 143 serum samples from dogs that tested seropositive for different vector-borne pathogens were assessed by SPE. Cases with abnormal globulin fractions were further characterized by IF. Protein fraction and IF labeling results were evaluated using Kruskal-Wallis with Dunn's multiple comparisons and principal component analysis (PCA).

Results: IF was performed in 112 VBD-seropositive samples with dysproteinemia evaluated by SPE. Most (84/112, 75%) had a polyclonal expansion. Only two dogs had findings suggestive of an M-protein when considering both SPE and immunofixation. PCA clustered E.canis/A.phagocytophilum and B.gibsoni/CM.haematoparvum groups with relatively more γ-globulins than albumin and α-globulins, and the B.gibsoni/CM.haematoparvum group with more prominent IgA and IgM labeling than IgG labeling. Additionally, D.immitis clustered with more prominent β-globulins than γ-globulins and more IgG4 than IgG-FC.

Conclusions: The previously derived interpretative criteria suggested an M-protein in very few VBD-seropositive dogs. PCA identified SPE and immunofixation pattern differences between dogs seropositive for different infectious agents.

Keywords: Dirofilaria spp.; Ehrlichia spp.; Leishmania spp.; M‐protein; dysproteinemia; infectious disease; monoclonal gammopathy; neoplasia; paraproteinemia.

FIGURE 1

Total protein and electrophoretic serum protein fractions on 112 canine serum samples that tested seropositive for at least one vector‐borne disease. Pairwise differences and the p‐value, as determined by the Kruskal–Wallis test with Dunn's multiple comparisons, are depicted. A.phag: Anaplasma phagocytophilum; B.gib/M.hema: Babesia gibsoni/Candidatum Mycoplasma haematoparvum group; B.burg: Borrelia burgdorferi; D.imm: Dirofilaria immitis; E.can: Ehrlichia canis; E.can/A.phag: Ehrlichia canis/Anaplasma phagocytophilum group; L.inf: Leishmania infantum.

FIGURE 2

Serum protein electrophoresis and immunofixation from a dog that tested seropositive for E. canis and grouped as a restricted polyclonal gammopathy. There is a series of predominantly γ‐globulin restrictions in a polyclonal expansion that label with IgG4 and IgG‐FC. Total protein was 9.5 g/d.

FIGURE 3

Serum protein electrophoresis and immunofixation from a dog which tested seropositive for Leishmania infantum and grouped as a restricted polyclonal gammopathy. There is a tall IgM‐labeling β2 peak and multiple IgG‐FC labeling β‐ and γ‐ globulin restrictions in a polyclonal expansion. Total protein was 9.4 g/dL.

FIGURE 4

Serum protein electrophoresis and immunofixation from a dog which tested seropositive for D.immitis and grouped as a restricted polyclonal gammopathy. There is a tall β1 peak with marked and diffuse IgG4 labeling. Total protein was 10.2 g/dL.

FIGURE 5

Serum protein electrophoresis and immunofixation from a dog which tested seropositive for E.canis and grouped as a monoclonal gammopathy. There is a pair of low‐concentration IgA restrictions in the β1‐β2 region without a prominent polyclonal expansion. Total protein was 6.1 g/dL.

FIGURE 6

Serum protein electrophoresis and immunofixation from a dog which tested seropositive for D. imm itis and grouped as a monoclonal gammopathy. There is a single low‐concentration IgG‐FC restriction in the γ‐globulin region without a prominent polyclonal expansion. Total protein was 6.8 g/dL.

FIGURE 7

PCA loading of electrophoretic fraction percentages. Three principal components were extracted.

FIGURE 8

Median PC scores between groups for electrophoretic fraction percentages. Pairwise differences and the p‐value as determined by the Kruskal–Wallis test with Dunn's multiple comparison are depicted. A.phag: A. phagocytophilum; B.gib/M.hema: Babesia gibsoni/Candidatum Mycoplasma haematoparvum group; B.burg: Borrelia burgdorferi; D.imm: Dirofilaria immitis; E.can: Ehrlichia canis; E.can/A.phag: Ehrlichia canis/Anaplasma phagocytophilum group; L.inf: Leishmania infantum.

FIGURE 9

PCA loading of the area under the curve of the immunoglobulin heavy chain labeling by immunofixation.

FIGURE 10

Median PC scores between groups. Pairwise differences and the p‐value as determined by the Kruskal–Wallis test with Dunn's multiple comparison are depicted. A.phag: A. phagocytophilum; B.gib/M.hema: Babesia gibsoni/Candidatum Mycoplasma haematoparvum group; B.burg: Borrelia burgdorferi; D.imm: Dirofilaria immitis; E.can: Ehrlichia canis; E.can/A.phag: Ehrlichia canis/Anaplasma phagocytophilum group; L.inf: Leishmania infantum.