Distinctive sensitivity of some T-leukemia cell lines to L-asparaginase.

Forty-two human hematopoietic cell lines were assessed for sensitivity to a four-day incubation with L-asparaginase. Eight of 13 T-leukemia cell lines and 1 of 7 non-T, non-B common acute lymphoblastic leukemia cell lines exhibited an ID50 (50% growth inhibition dose) of less than 0.0001 IU/ml. Seven of these sensitive cell lines were further cultured in L-asparagine-free medium and were found not to proliferate. Five T-leukemia cell lines, 6 non-T, non-B common acute lymphoblastic leukemia cell lines, 10 "abnormal" B-cell lines, 4 "normal" B-cell lines, 3 myeloma cell lines and 5 myeloid leukemia cell lines had ID50 values between 0.1 and 1.0 IU/ml. Twelve of these resistant cell lines were able to proliferate in L-asparagine-depleted medium. The results indicate that some patients with T-cell acute lymphoblastic leukemia might respond to this enzymatic antineoplastic drug, L-asparaginase, at low dose.