PRIOR CONCURRENT THERAPY: Biologic therapy: At least 6 weeks since prior immunotherapy and recovered Chemotherapy: At least 6 weeks since prior chemotherapy and recovered Endocrine therapy: No concurrent systemic corticosteroids Radiotherapy: At least 6 weeks since prior radiotherapy and recovered Surgery: See Disease Characteristics No prior splenectomy Other: At least 6 weeks since other prior experimental anticancer therapy and recovered No concurrent non-steroidal anti-inflammatory drugs or other immunosuppressive drugs No other concurrent participation in a clinical trial