353. In a Model of Tumor Dormancy, Long-Term Persistent Leukemic Cells Have Increased B7-H1 and B7.1 Expression and Resist CTL-Mediated Lysis

Abstract

Tumor dormancy is a condition in which tumor cells persist in the host for a long period of time but do not grow. We previously reported that in the DA1-3b/C3H mouse model of acute myeloid leukemia (AML), vaccination of mice with leukemia cells transduced with CD154, GM-CSF, B7.1, or IL12 led to significant protection, and generated specific cytotoxic T cells (CTL) against leukemic cells. In spite of these effective anti-leukemic responses, we detected MRD in a fraction of long-term surviving mice. We then decided to investigate how myeloid leukemic cells could persist for months in the host, in spite of an effective anti-leukemic immune response.