The role of lesional T cells in recalcitrant psoriasis during infliximab therapy

With infliximab therapy (anti-TNF-alpha) for plaque psoriasis, over 80% of patients reach > or = 75% PASI improvement in 10 weeks of treatment. We describe a patient with severe recalcitrant psoriasis who was treated with infliximab 5 mg/kg for 22 weeks. Rather than the expected improvement, this patient experienced an initial exacerbation, followed by the lack of efficacy over the entire 22-week period of treatment. Before, during and after treatment we performed immunohistochemical analyses on lesional biopsies, with respect to T cells, NK-T cells, epidermal growth and differentiation. We found a discrepancy between the clinical aggravation and marked reductions of lesional T cell subsets. The most prominent decrease was for CD4+ T cells (72-74%), which suggests that a reduction of T cells in the psoriatic plaque might not be a guarantee for positive clinical outcomes. Remarkably, the number of epidermal CD94+ NK-T cells correlated fairly well with the lack of clinical efficacy, supposing a pathogenic role for these cells in psoriasis. Further studies are needed to clarify the ambiguous role of conventional pathogenic T cells in plaque psoriasis.