Background: The Goeckerman regimen (GR) involves the dermal application of a crude coal tar (polycyclic aromatic hydrocarbon, PAH) and exposure to ultraviolet (UV) radiation. Both PAH and UV radiation exhibit immunosuppressive activity. This study describes the changes in the serum levels of the pro-inflammatory cytokine interleukin-12 (IL-12) and the anti-inflammatory cytokine IL-10 in patients with psoriasis (n = 55) treated with GR.
Methods: The serum levels of IL-12 and IL-10 were compared before and after GR. In addition, the IL-12 and IL-10 levels in psoriatic patients were compared with those in a control group of healthy blood donors (n = 47). The Psoriasis Area and Severity Index (PASI) was used to evaluate the efficacy of GR.
Results: When compared with the control group, both IL-12 and IL-10 were significantly higher in psoriatic patients in all cases (P < 0.001). When compared before and after GR, the IL-12 and IL-10 levels (P < 0.01) and PASI value (P < 0.001) were significantly lower after GR. The decrease in the serum level of IL-12 and IL-10 after GR was related to the entry value before GR (IL-12, r = 0.60, P < 0.001; IL-10, r = 0.36, P < 0.01). There was a significant correlation between the IL-10 level before GR and the PASI value after GR (r = -0.39; P < 0.01).
Conclusions: The results indicate a strong pro-inflammatory effect of IL-12 in the immunopathogenesis of psoriasis, and confirm the immunosuppressive and anti-inflammatory effect of GR. IL-10 seems to be a promising individual marker for a positive effect of GR therapy.