- Has used any systemic immunomodulatory therapy known to affect psoriasis that DOES typically decrease immune cell populations (e.g. alefacept) within the 36 weeks prior to start of treatment.- Subject has used any systemic immunomodulatory therapy known to affect psoriasis that DOES NOT typically decrease immune cell populations (e.g. efalizumab, etanercept, infliximab, adalimumab, and any investigational anti-TNF or anti-IL-12/23 agents) within 12 weeks prior to start of treatment.