AUTOMATED RETICULOCYTE COUNTING FOR MONITORING PATIENTS ON CHEMOTHERAPY FOR ACUTE LEUKEMIAS AND MALIGNANT-LYMPHOMAS

Flow cytometric reticulocyte counting including their maturation fract ions was performed with a Sysmex R-3000(TM) automated analyser during follow-up after induction and/or consolidation with combination chemot herapy in patients with acute leukaemias (AL, n = 39; 58 courses) and malignant lymphomas (ML, n = 21; 29 courses). The ML patients received granulocyte colony stimulating factor (G-CSF) in addition after chemo therapy. During the leucopenic phase only reticulocytes of low fluores cence ratio (LFR) at extremely low concentration (< 10 x 10(9)/l) were found. After a median interval of 17 days (range 8-43), the middle fl uorescence fraction (MFR) began to rise, preceding high fluorescence r atio (HFR) reticulocytes by a median of 1 day in AL patients with comp lete or partial remission, In ML patients, MFR and HFR reticulocytes a ppeared more often simultaneously after a median internal of only 11 d ays (range 8-15) and increased faster during the first week of marrow recovery showing a pattern different from AL. Granulocytes passed the critical limit of 0.5 x 10(9)/l at a median of 5 days after appearance of MFR reticulocytes in AL but in ML on the same day as MFR and HFR ( day 0). The absolute reticulocyte concentration reached the lower limi t of the reference range after about 10 days in AL. Thus, finding MFR and, to a lesser extent, HFR at very low cell concentrations, may serv e as sensitive early indicators of marrow recovery after chemotherapy and are much more sensitive parameters than the absolute reticulocyte concentration. The higher median values for reticulocytes (total, HFR and MFR) after G-CSF therapy suggests that G-CSF is not lineage specif ic and may also stimulate erythroid precursor cells.