Ipilimumab With or Without Vaccine Therapy in Treating Patients With Previously Treated Stage IV Melanoma

RATIONALE: Monoclonal antibodies, such as ipilimumab, can block tumor growth in different ways. Some block the ability of tumor cells to grow and spread. Others find tumor cells and help kill them or carry tumor-killing substances to them. Vaccines made from gp100 peptides may help the body build an effective immune response to kill tumor cells. Giving ipilimumab together with vaccine therapy may be an effective treatment for melanoma. PURPOSE: This randomized phase II trial is studying ipilimumab and vaccine therapy to see how well they work compared to ipilimumab alone in treating patients with previously treated stage IV melanoma.