PV involves blistering of the outer layer of skin and mucous membranes, causing a separation of epidermal cells. The disease occurs when the immune system produces antibodies to specific proteins in the skin and mucous membranes; the cause for production of these autoantibodies is unknown. Infliximab is a genetically engineered monoclonal antibody directed against tumor necrosis factor (TNF)-alpha, a chemical messenger that activates an immune response. Infliximab has been used to treat other autoimmune disorders, including rheumatoid arthritis, ankylosing spondylitis, and Crohn's disease. This study will evaluate the safety and efficacy of infliximab given in combination with prednisone for the treatment of adults with PV.