Peripheral Blood: Implications for the Surveillance of Patients With Lymphoblastic Leukemia or Lymphoma in Remission

An indirect immunofluorescence assay was used to quantitate TdT-containing (TdT ) cells in the mononuclear leukocyte fraction of peripheral blood from normal subjects and patients with acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LL). In normal children (10) and adults (10). 0.036% ± 0.014% (mean ± SD) and 0.030% ± 0.01 5% TdT cells were found. In peripheral bloods from 1 0 children receiving chemotherapy for tumors other than ALL or LL, 0.040% ± 0.039% TdT cells were found. Serial determinations were performed on 15 patients with ALL or LL who were in clinical remission. Eight of these patients remained in continuous remission and always had fewer than 0.1 1 % TdT cells in their