1. Experimental Dermatology Unit, Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
2. ^*Department of Dermatology, Karolinska Hospital, Stockholm, Sweden
3. ^†Department of Dermatology, University Hospital, Uppsala, Sweden
4. ^‡Department of Dermatology, University of Rostock, Rostock, Germany
5. ^§Department of Pathology, University Hospital Nijmegen, HB Nijmegen, the Netherlands

Correspondence: Prof Olle Johansson, Experimental Dermatology Unit, Department of Neuroscience, Karolinska Institute, 17177 Stockholm, Sweden

Received 6 March 1998; Revised 19 June 1998; Accepted 1 October 1998.

Abstract

Immunohistochemistry was applied in the investigation of the possible existence of serotonin in human skin. It was found that epidermal melanocytes express a serotonin-like immunoreactivity. The immunoreactivity was associated with both the cytoplasm and the cellular membrane, though the latter was only found in certain cells. The serotonin anti-serum labeled the same cells as NKI-beteb, which is known as a reliable marker of melanocytes. Blocking experiments showed that both serotonin and NKI-beteb have different epitopes in the melanocytes. In in vitro studies, serotonin-like immunoreactivity appeared in 90% of cultured human melanocytes, and was found both in the cytoplasm and also in the nuclei. Thus, we believe the melanocytes to be the origin of serotonin (or a serotonin-like molecule) in the skin.