OBJECTIVES: I. Determine the optimal dose of Thompson-Friedenreich [TF(c)]-keyhole limpet hemocyanin (KLH) conjugate plus adjuvant QS21 that induces an antibody response in patients with prostate cancer. II. Determine the safety of the TF(c)-KLH conjugate prepared using an MBS heterobifunctional linker plus QS21. III. Assess postimmunization changes in prostate specific antigen levels and other objective parameters of disease in these patients.