Study of the Drug Efalizumab (Raptiva), for Adult Patients With Moderate to Severe Plaque Psoriasis

The eligible patient will receive the drug Efalizumab, weekly for 12 weeks, by injection. The patient will be seen weekly for 12 weeks and every other week for the 12 weeks of follow up. At those visits, the patient can expect that a physical and skin exam will be done. At specific weeks, blood work will be drawn, clinical photography taken and a skin biopsy done. Two types of skin biopsies will be done after local anesthesia has been administered. One is a punch biopsy where a small piece of skin will be taken, the approximate size of a pencil eraser. The second type of skin biopsy is shave biopsy, where a postage sized piece of skin will be taken.