The expression of the c-kit receptor by epidermal melanocytes may be reduced in vitiligo.
The proto-oncogene c-kit encodes the transmembrane tyrosine kinase receptor that has a role in the growth regulation of various cell types including melanocytes. In the present study we have examined the expression of the c-kit protein in the skin of seven patients with vitiligo. Melanocytes positive for c-kit protein were observed in the basal layer in non-lesional skin and the mean number of 25.8 +/- 5.2 (per 200 basal cells) compared with that of 21.8 +/- 3.5 from six control subjects. In perilesional skin there was a reduction in the numbers of c-kit positive melanocytes (6.7 +/- 2.6) and this was especially noticeable in six of the seven patients. Such a reduction was less obvious following staining with MEL-5 and in only two subjects were the numbers of melanocytes below the normal range. This suggests that the reduction in c-kit staining was the result of decreased expression of the protein rather than a loss of melanocytes. No melanocytes, positive for c-kit protein, or after staining with MEL-5, were identified in lesional skin although isolated tyrosinase-positive melanocytes were seen in one subject. There was no apparent change in the numbers of mast cells expressing c-kit protein and the intensity of staining in the dermis even in lesional skin was similar to that in the controls. These results demonstrate that c-kit protein is present on melanocytes in adult human skin and that in perilesional skin of some vitiligo patients there is a reduction in the numbers of melanocytes expressing this receptor. Whether this may contribute to the defective melanocyte growth and/or survival that occurs in vitiligo or whether it is a consequence of melanocyte damage remains to be seen.
Norris
A
A
Department of Dermatology, University of Newcastle upon Tyne, U.K.
Todd
C
C
Graham
A
A
Quinn
A G
AG
Thody
A J
AJ
D000328:Adult; D016022:Case-Control Studies; D002452:Cell Count; D004817:Epidermis / Q000737:chemistry; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008544:Melanocytes / Q000737:chemistry*; D008875:Middle Aged; D000090063:Proto-Oncogene Mas; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis*; D012867:Skin / Q000737:chemistry / Q000473:pathology*; D014820:Vitiligo / Q000473:pathology
C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D019009:Proto-Oncogene Proteins c-kit