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.