Asynchronous Expression of AC133 on CD34-Negative Leukemic Blast Cells in Childhood B-Cell Precursor ALL

Expression of AC113 was studied in the bone marrow of 17 patients with B-cell precursor ALL and 4 normal controls. 11 of 17 patients (65%) expressed AC 133 on 1% to 99% of the leukemic blast cells. 6 patients (35%) had no AC 133 expression detectable within the leukemic clone. Interestingly and in contrast to normal bone marrow, 6 patients showed an asynchronous expression of AC133 on CD19+CD34 blasts. There was no correlation between the expression of AC 133 and CD34 within the leukemic cell clone or the expression of AC 133 and the immunulogical ALL subtype. This abnormal expression pattern of AC 133 may be useful in monitoring minimal residual disease.