The receptor for erythropoietin is present on cutaneous mast cells.

Skin samples from patients with extra-mammary Paget disease, Bowen's disease, atopic dermatitis, psoriasis and non-lesional skin of nevus pigmentosus were immunohistochemically examined with an anti-soluble erythropoietin receptor antibody (anti-sEPOR antibody), and only the dermal mast cells positively stained in all skin samples were examined. These positively stained dermal cells were proved to be mast cells by double staining with anti-sEPOR antibody and either with anti-bikunin antibody or anti-tryptase antibody. Immunoelectron microscopically these EPOR were found in the secretory granules of the dermal mast cells. Further, EPOR in the mast cells may be consisting of only the extracellular domain of erythropoietin receptor molecule as the mast cells were immunohistochemically not reacted with an antibody to the C-terminal peptide of EPOR. Human mast cell line, HMC-1 cells has immunohistochemically the erythropoietin receptor, which was consisting of a 43 kDa major protein and a 20 kDa minor protein in the immunoelectrophoresis. These data may indicate that EPOR in the mast cells may not be the whole molecule, but probably the soluble one of EPOR.