DISEASE CHARACTERISTICS:

• Histologically confirmed stage IV melanoma
• Clinically evaluable or measurable disease
• No mucosal or ocular melanoma

PATIENT CHARACTERISTICS:

Age

• 16 and over

Performance status

• ECOG 0-2

Life expectancy

• At least 6 months

Hematopoietic

• Absolute neutrophil count ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3
• Hemoglobin ≥ 9 g/dL
• Hematocrit ≥ 28%
• WBC ≥ 2,500/mm^3

Hepatic

• AST ≤ 3 times upper limit of normal (ULN)
• Bilirubin ≤ ULN (< 3 mg/dL for patients with Gilbert's syndrome)
• Hepatitis B surface antigen negative
• Hepatitis C virus antibody negative

Renal

• Creatinine < 2 mg/dL

Immunologic

• HIV negative

• No history of any of the following:

  • Inflammatory bowel disease
  • Regional enteritis
  • Connective tissue disorders (e.g., systemic lupus erythematosus)
  • Rheumatoid arthritis
  • Autoimmune inflammatory eye disease
  • Sjögren's syndrome
  • Inflammatory neurologic disorder (e.g., multiple sclerosis)
• No active infection

• No active autoimmune disease that may cause life-threatening symptoms or severe organ/tissue damage

  • Vitiligo, autoimmune thyroiditis, or skin rashes associated with prior therapy are allowed if patient has recovered to grade 1 or less toxicity

• No systemic hypersensitivity to study agents

  • Prior local reaction (e.g., delayed hypersensitivity or glaucomatous reactions) to Montanide ISA-51 or gp100 injections allowed
• No autoimmune disease requiring active therapy with any form of steroid or immunosuppressant

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No concurrent underlying medical condition that would preclude study participation
• No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer, superficial bladder cancer, or carcinoma in situ of the cervix

PRIOR CONCURRENT THERAPY:

Biologic therapy

• No prior anti-cytotoxic T-lymphocyte-associated antigen-4 monoclonal antibody
• Prior therapy with gp100 peptides or any other immunotherapy allowed

Chemotherapy

• At least 6 weeks since prior nitrosoureas and recovered (toxicity no greater than grade 1)
• No concurrent chemotherapy

Endocrine therapy

• At least 4 weeks since prior steroids
• No concurrent systemic, inhaled, optical, or topical corticosteroids

Radiotherapy

• Not specified

Surgery

• Not specified

Other

• At least 3 weeks since prior systemic therapy for melanoma and recovered (toxicity no greater than grade 1)
• No concurrent immunosuppressive agents (e.g., cyclosporine)