Tumor-Inhibitory Antibiotic Uptake Facilitated by Leukoregulin: A New Approach to Drug Delivery

: The uptake of tumor-inhibitory antibiotics by human K562 erythroleukemia cells was examined in the presence of leukoregulin to determine if the lymphokine's ability to increase the plasma membrane permeability of tumor cells facilitates concurrent entry of pharmacologically active molecules. K562 cells were exposed to 0.25-2.0 micrograms of doxorubicin/mL for up to 60 minutes at 37 degrees C. Commencing within 15 minutes, leukoregulin increased the entry of doxorubicin approximately twofold and the uptake of mitomycin, mithramycin, and propidium iodide twofold to tenfold. This finding indicates the potential biotherapeutic value of leukoregulin in promoting the selective entry of pharmacologically active molecules into leukoregulin-sensitive target cells.