Study of Merkel cells in the dog through the immunohistochemical expression of five different commercial antibodies: comparative analysis

Merkel cells (MCs) are cutaneous specialized cells with a wide immunohistochemical profile, including low molecular weight cytokeratins and various endocrine and neural markers. Differences in expression of these markers may be a consequence of contradictory results in studies of MCs in normal and damaged canine tissues. The present study aimed to compare five different commercial available antibodies developed against cytokeratins 8+18 and 20, neuron-specific enolase, chromogranin A, and synaptophysin on formalin-fixed paraffin-embedded samples of hard palate, cheek skin including sinus hair follicles or vibrissae, nasal planum, and footpads. The antibodies showed great variability with respect to quality and intensity of immunoreactivity to identify MCs. Anti-Cytokeratin 20 antibody is more effective to recognize MCs in the dog skin followed by the antibodies against neuron-specific enolase, cytokeratins 8 and 18, chromogranin A, and synaptophysin. There was also a significant difference in intensity of immunoreaction scores between them depending on the location examined. These results represent a necessary basic background for future studies of the role of these cells in normal and damaged canine tissues.