Immunological detection of residual leukaemic disease in the bone marrow of children with acute lymphoblastic leukaemia

Peripheral blood lymphocytes incubated with tumour cells or extracts may undergo blastogenesis. This is the basis of a technique studied in children with acute lymphoblastic leukaemia (ALL) in childhood in an attempt to predict relapse. Samples of peripheral blood and bone marrow from 82 children with varying degrees of ALL were analysed. Cultures were prepared by incubating a lymphocyte suspension with an autologous bone-marrow suspension. All were pulse-labelled with 3H-TdR and radioactivity was measured by scintillation counting. Results were expressed as the stimulation index, calculated by dividing the mean counts per minute (cpm) of wells containing both lymphocytes and bone-marrow cells by the sum of the mean cpm for control wells. If the stimulation index exceeded 1 at 72, 96 or 120 hours, a positive response was recorded. During the study no patient relapsed who had not shown a positive response and none of the 6 children in clinical relapse responded. Six 'true false positives' were recorded. The technique merits further study as a guide to the presence of leukaemic cells. (author)