Interaction of albumin and vincristine with a human lymphoblastic leukemia cell line in vitro

To investigate the potential influence of albumin on the antitumor effect of vincristine (VCR), cells from a human lymphoblastic leukemia cell line (CEM) were exposed in vitro to albumin and a clinically attainable VCR concentration (10(-7)M). Increasing concentrations of albumin between 1 and 4 g/100 ml resulted in a corresponding reduction of VCR-induced growth suppression. Studies employing tritiated vincristine ([3H]-VCR) revealed a progressive inhibition of uptake of the radio-label into CEM cells with increasing concentrations of albumin. These in vitro data show a previously unrecognized protective effect of increasing concentrations of albumin on the growth of human lymphoblastic leukemia cells exposed to VCR as a consequence of inhibition of drug uptake. Further in vivo pharmacologic studies will be necessary to determine their clinical significance.