Patients undergo blood sample collection periodically for correlative laboratory studies. Samples are analyzed for immune responses to keyhole limpet hemocyanin and tetanus toxoid (control antigens) by ELISA assay; IFN-γ production by CD8 T cells in response to melanoma-derived peptides by ELISpot assay; delayed-type hypersensitivity response to vaccination; and frequency of peripheral blood lymphocytes, including T cells, B cells, NK cells, and monocytes, by flow cytometry.