Fig. 1.

Structure of the Dox–PHPMA–HuIg conjugate. The Dox–PHPMA–HuIg conjugate consists of the HPMA [poly-N-(2-hydroxypropyl)methacrylamide] backbone, which was modified by biodegradable oligopeptide side chains terminating in the targeting immunoglobulin molecules, and the drug (Dox) randomly distributed along the polymer chain. Structure of the Dox–PHPMA conjugate is identical, except that it does not contain the immunoglobulin molecule, and the side chains end with Dox only (z = 0). Comparison of the IC50 values of the free Dox and HPMA-based conjugates Dox–PHPMA and Dox–PHPMA–HuIg: IC50 values were calculated as the concentration of Dox which inhibits the incorporation of [³H]thymidine to 50% of the control level. The EL-4.IL-2 cells were incubated at 5 × 10⁴ per well with different concentrations of the tested samples for 2 days, and proliferation of cells was measured by [³H]thymidine incorporation. Data are representative of at least three independent experiments