Evaluation of early post-transplant leukocyte recovery using the undiluted erythrocyte lysing technique.

The undiluted erythrocyte lysing technique was evaluated to see if it provides more accurate total leukocyte counts and differential leukocyte counts of severely leukopenic blood samples, in order to detect the onset of hematopoietic recovery after stem cell transplantation. Leukocyte counts using the conventional automated cell counting technique were found to be inaccurate, especially in blood samples with total leukocyte counts < 500/microl. In cases where the difference between results by the two methods was >100/microl, a positive correlation was found between the difference value and the blood reticulocyte count (r = 0.39, p = 0.002). Hematopoietic recovery after stem cell transplantation in a group of patients with chronic myelogenous leukemia (CML) was different from that of non-CML groups. In the CML group, the initial leukocyte counts were higher and the number of days until neutrophil recovery was higher than in the non-CML groups. Also, the day on which the absolute neutrophil count (ANC) exceeds 100/microl could serve as an indicator of neutrophil recovery. This study shows that the undiluted erythrocyte lysing technique can be used to count leukocytes accurately, especially in severely leukopenic samples. This new method can detect neutrophil recovery at ANC > 100/microl, as well as at an earlier date than the conventional method.