PRIOR CONCURRENT THERAPY: Biologic therapy: At least 2 weeks since prior biologic or immunotherapy No other concurrent biologic or immunotherapy Chemotherapy: At least 4 weeks since prior chemotherapy (6 weeks for mitomycin or nitrosoureas) No concurrent chemotherapy Endocrine therapy: At least 2 weeks since prior corticosteroids No concurrent systemic glucocorticosteroids Radiotherapy: At least 2 weeks since prior radiotherapy No concurrent radiotherapy Surgery: Not specified Other: No concurrent immunosuppressants