Serum neopterin as an objective marker of psoriatic disease activity.

Neopterin is a non-specific marker of the activation of cell-mediated immunity. Several studies have demonstrated the crucial role of CD4+ T cells in the pathogenesis of psoriasis. We have measured serum and urine neopterin levels and urine neopterin/creatinine ratios by radioimmunoassay in 24 patients with plaque-type psoriasis before and after a course of topical treatment with triamcinolone acetonide 0.1% and coal tar 4%. Results were compared with a group of 20 healthy, non-psoriatic volunteers. Serum neopterin levels were significantly elevated in the psoriatic group compared with the control group (p=0.001) and were significantly reduced after treatment (p=0.01). There was a correlation between pretreatment serum neopterin levels and psoriasis area and severity scores (PASI) (r=0.37, p=0.03) and also for pretreatment neopterin/creatinine ratios and PASI scores (r=0.45, p=0.01). These findings indicate that serum neopterin concentrations reflect disease activity in psoriasis.