Evaluate Whether Combination Therapy With Methotrexate and Raptiva in Psoriasis Patients is Safe and Increases Efficacy

The primary objective of this study is to evaluate whether a short-term course of methotrexate in patients treated with efalizumab (Raptiva) increases efficacy. The secondary objectives of this study are 1) to evaluate the efficacy of Raptiva in maintaining the clinical improvement induced by short-term treatment with combination therapy of Raptiva and methotrexate 2) to evaluate the safety of short-term combination therapy of Raptiva and methotrexate. The design of this study is to gain better control of the disease process while reducing potential toxicities by beginning treatment with Raptiva and adding methotrexate to those patients who do not improve significantly