A Study of Efalizumab in Participants With Moderate to Severe Chronic Psoriasis Who Have Failed, Have a Contraindication to, or Are Intolerant of Other Systemic Therapies

Participants will receive efalizumab 1.0 milligram per kilogram (mg/kg) (with an initial conditioning dose of 0.7 mg/kg) once weekly by subcutaneous injection for 12 weeks (first treatment \[FT\]). Depending on the response at Week 12, participants could receive additional 8 to 12 weekly injections of efalizumab 1.0 mg/kg.