cysteinyldopa and Erythema

5-S-Cysteinyldopa (5-S-CD) is found in all pigment-producing cells and is the major precursor of phaeomelanin. However, the melanocyte specificity of the compound has been questioned. In order to elucidate the origin of 5-S-CD, we have now systematically studied the relationship between the 5-S-CD excretion in urine and the size of the melanocyte organ, UV-induced melanocyte proliferation, skin type, and the erythemal reaction. The skin type had no influence on the basal excretion of 5-S-CD. There was no significant correlation between the basal 5-S-CD excretion and the size of the melanocyte organ; that is, the number of skin melanocytes and nevi. During the irradiation, subjects with skin type II developed a more pronounced erythema (p less than 0.01) and had a significantly higher 5-S-CD excretion than those with skin type III-IV (p less than 0.01). No correlation was found between 5-S-CD excretion and UV-induced melanocyte proliferation. The lack of correlation between the basal 5-S-CD excretion and skin type or number of melanocytes suggests that the basal 5-S-CD in urine is mainly of extra-melanocytic origin. Our findings favor the view that the increase in 5-S-CD excretion during UV irradiation is due to UV damage.

Topics: Adult; Biomarkers, Tumor; Cell Division; Cysteinyldopa; Dihydroxyphenylalanine; Epidermal Cells; Epidermis; Erythema; Female; Humans; Male; Melanocytes; Middle Aged; Skin; Ultraviolet Rays