Anti-Leishmania infantum Antibody-Producing Plasma Cells in the Spleen in Canine Visceral Leishmaniasis

The spleen is involved in visceral leishmaniasis immunopathogenesis, and presents alterations in white-pulp microenvironments that are associated with an increased susceptibility to coinfections and patient death. Plasmacytosis in splenic red pulp (RP) is one observed alteration, but the specificity of antibody-secreting cells and the distribution of them has not yet been evaluated. We biotinylated soluble L. infantum membrane antigens (bSLMA) used as probes in modified immunohistochemistry, and detected the presence of anti-L. infantum antibody-secreting cells. Were used spleens from eight dogs from the endemic area for canine visceral leishmaniasis (CanL), and three healthier controls. The spleen sections were cryopreserved, and we performed modified immunohistochemistry. The ratio of plasma cells which were reactive to bSLMA (Anti-Leish-PC) in the spleen RP and periarteriolar lymphatic sheath (PALS) were calculated. Dogs with CanL present hyperglobulinemia and more plasma cells in their RP than the controls. Furthermore, dogs with CanL presented a lower proportion of Anti-Leish-PC in their RP than in PALS. Likewise, dysproteinemia was related to RP and PALS plasmacytosis, and a more severe clinical profile.

Automated summary

The spleen plays a crucial role in the immunopathogenesis of visceral leishmaniasis, with alterations in white-pulp microenvironments increasing susceptibility to coinfections and mortality in patients. Using modified immunohistochemistry with biotinylated soluble L. infantum membrane antigens, researchers detected the presence of anti-L. infantum antibody-secreting cells in spleen sections from CanL-affected dogs. CanL dogs displayed hyperglobulinemia and more plasma cells in their RP compared to healthier controls, with a lower proportion of Anti-Leish-PC in RP than in PALS. Dysproteinemia was associated with plasmacytosis in both RP and PALS, correlating with a more severe clinical presentation.