Study to measure the immune response to the influenza vaccine in patients with chronic plaque psoriasis

Interleukin-12 (IL-12) and interleukin-23 are heterodimeric cytokines, with a common p40 subunit and a unique chain (IL-12p35 and IL-23p19). The p40 subunit of both interleukins binds to the transmembrane IL-12 receptor-beta1 (IL-12R ) on the surface of T lymphocytes and natural killer cells. Ustekinumab is a fully human monoclonal antibody, anti-IL12p40, which binds to the p40 subunit of IL-12 and IL-23 with high affinity and specificity, inhibiting the activity of both interleukins. Ustekinumab has proven to be highly effective in the treatment of chronic plaque psoriasis, with up to 76% of patients achieving a 75% reduction in their psoriasis area and severity index (PASI-75).1, It is routinely recommended that psoriasis patients treated with biologic therapies such as ustekinumab be vaccinated annually with the influenza vaccine. We can thus assess the importance of these cytokines in the immune response to vaccination by comparing the immune response to influenza vaccination of psoriasis patients treated with ustekinumab with that of patients who are not receiving this treatment. We will assess gene expression profiles and white blood cell subsets in the blood of psoriasis patients before vaccination and at multiple time-points after vaccination.