Effects of narrowband UV-B on pharmacodynamic markers of response to therapy: an immunohistochemical study over sequential samples

Background: To evaluate the effects of narrow‐band UV‐B (NBUVB) on the immunohistochemical markers of cellular and cytokine activation as well as of abnormal epidermal differentiation and proliferation – pharmacodynamic markers of response to therapy (PMT)– in psoriatic lesions. Methods: Clinical assessments and immunohistological staining of formalin‐fixed paraffin sections of biopsies from psoriatic skin were done at baseline and at the end of the treatment period. Results: Ten patients with chronic plaque‐type psoriasis were included. After treatment with NBUVB, the total number of CD3+, CD4+ and CD8+ T cells was reduced by an average of 86.6%, 86% and 85% in the epidermis and 70.3%, 70% and 62% in the dermis, respectively. Only the decrease in the number of epidermal CD4+ cells was statistically related with long‐lasting remissions. The mean reduction in the expression of keratinocyte proliferation markers after NBUVB was 62%, 68% and 81% for Ki‐67, cyclin A and cyclin B, respectively. Expression of suprabasal keratin 16 and filaggrin was almost normalized in most cases. All patients in whom expression of keratin16 remained after finishing UV‐B therapy had an early relapse. Conclusions: NBUVB is associated with changes in PMT close to those seen after remittive therapies. The normalization of immunohistochemical parameters of differentiation and the reduction/depletion in epidermal CD4+ cells was the most important markers of long‐lasting remissions.