5-S-Cysteinyldopa and
dopa concentrations in serum were studied by high-performance liquid chromatography (HPLC) in patients with
psoriasis treated by
8-methoxypsoralen and UVA light. A marked increase in
5-S-Cysteinyldopa was found after 3 days' treatment, although no increase in pigmentation could yet be observed. The highest concentrations of
5-S-Cysteinyldopa in serum were noted after 1 or 2 weeks' treatment. In one patient who showed no increase in serum
5-S-Cysteinyldopa treatment was unsuccessful. During PUVA treatment of 3 patients with
psoriasis confined to the palms and/or soles a delayed increase in serum
5-S-Cysteinyldopa was noted after 5 weeks. This delayed response
after treatment of a small area of the body is remarkable, and may indicate the formation of a systemic melanocyte stimulation factor. There was no increase in the serum
dopa concentrations during PUVA treatment, and
dopa analysis was of no value in assessing the activity of the melanocytes. Some unexpectedly high
dopa values recorded before and during PUVA treatment may be explained by the fact that
dopa originates in the nervous system or the adrenals.