Immunophenotypic and Immunogenotypic Detection of Minimal Residual Disease in Acute Lymphoblastic Leukemia

Despite major improvements in the treatment of patients with acute lymphoblastic leukemia’s (ALL) during the last two decades, still 20%–30% of children with ALL and 60%-75% of adult ALL patients will develop a relapse (Hoelzer et al. 1984; Linker et al. 1987; Riehm et al. 1990; Veerman et al. 1990; Ellison et al. 1991). Apparently, the current treatment protocols are not capable of killing all leukemic cells in these patients, although they seemed to be in complete remission according to cytomorphological criteria. Since the detection limit of cytomorphological techniques is 1%–5% leukemic cells, it is obvious that such techniques can only provide superficial information about the effectiveness of leukemia treatment. More sensitive techniques for the detection of low numbers of leukemic cells are needed to obtain better insight into the reduction of tumor mass during induction treatment and further eradication of the leukemic cells during maintenance treatment.