Desmoplakin and Plakoglobin--specific markers of lymphatic vessels in the skin?

Monoclonal antibodies against Desmoplakin and Plakoglobin were tested for their suitability as specific markers of lymphatic vessels. The tissue samples were taken from horse skin in an attempt to establish the horse as a model for human lymphatic diseases. To obtain a clear, positive identification of blood and lymphatic vessels, immunohistochemical staining with antibodies against vascular endothelial growth factor receptor 3 (VEGFR-3) and platelet endothelial adhesion molecule (PECAM-1, CD31), was compared with Desmoplakin and Plakoglobin. Because anti-VEGFR-3 is specific for lymphatic vessels in the skin while anti-CD31 stains blood and lymphatic vessels as well, it can be concluded that VEGFR-3(-)/CD31(+) vessels are blood vessels and VEGFR-3(+)/CD31(+) vessels are lymphatic vessels. It was documented on serial sections that Plakoglobin stains both blood and lymphatic vessels. However, Desmoplakin did not stain several positively identified lymphatic vessels. Therefore, Desmoplakin and Plakoglobin antibodies are not specific markers of lymphatic vessels in the skin and the staining pattern is tissues and species dependent.