TUMOR-CELL VACCINATION INDUCES TUMOR DORMANCY IN A MURINE MODEL OF B-CELL LEUKEMIA LYMPHOMA (BCL(1))/

Immunity to murine B-cell leukemia/lymphoma (BCL(1)) induced by multip le injections with irradiated tumor cells, prevented leukemia developm ent in primary and adoptive transfer recipients despite long-lasting p ersistence of residual tumor cells. Detection of dormant BCL(1) cells was carried out by PCR analysis using the V-H-rearranged DNA sequence as a BCL(1) clonal marker. Dormant tumor cells were detected >250 days following immunity induction in 40% of spleens from healthy immune mi ce having no detectable symptoms of disease. Tumor dormancy was not ab rogated by adoptive transfer of BCL(1)-containing splenocytes into syn geneic recipients, indicating that cell-mediated anti-tumor immunity c ontributes to maintenance of the tumor dormant state and prevents rene wed tumor-cell growth. Splenocytes but not sera from immune mice confe rred specific radiosensitive protection from a lethal dose of BCL(1) c ells included in cell mixtures transferred to secondary recipients. A therapeutic effect of transferred immune splenocytes was shown in BCL( 1)-bearing mice, which remained disease-free for >200 days after inocu lation; nevertheless, dormant BCL(1) cells were detected by PCR analys is in some of the surviving mice. Our results suggest that an efficien t tumor-cell vaccine can lead to induction of tumor dormancy that can be maintained by a cell-derived mechanism for a long period of time. ( C) 1996 Wiley-Liss, Inc.