Biorecognition of HPMA copolymer-adriamycin conjugates by lymphocytes mediated by synthetic receptor binding epitopes.
OBJECTIVE
The EDPGFFNVE nonapeptide (NP) was recognized as the CD21 (CR2) binding epitope of the Epstein-Barr virus (EBV) gp350/ 220 envelope glycoprotein which mediates the virus attachment to human B lymphocytes (Nemerow et al., Cell 56:369-377, 1989). Here we evaluated the targeting potential of a synthetic receptor binding epitope (NP) covalently attached to a water-soluble polymeric drug carrier. In particular, the biorecognition of N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-NP conjugates by B- and T-cells and the cytotoxicity of HPMA copolymer-NP-adriamycin (ADR) conjugates toward B-cells, T-cells, and peripheral blood lymphocytes (PBL) were evaluated.


METHODS
HPMA copolymer-NP and optionally ADR conjugates varying in the NP density and mode of NP attachment were incubated with Raji B-cells (human Burkitt's lymphoma), CCRF-CEM T-cells (acute human lymphoblastic leukemia), and CCRF-HSB-2 T-cells (human lymphoblastic leukemia). The kinetics of binding was studied, the Langmuir adsorption isotherms analyzed, binding constants calculated, and IC50 doses determined.


RESULTS
Flow cytometry studies revealed that binding was homogeneous to both cell types. The apparent binding constants to T-cells were about two times higher when compared to B-cells. The binding and cytotoxicity increased with increased amount of epitopes per polymer chain. Attachment of the NP via a GFLG spacer resulted in increased biorecognition when compared with conjugates containing NP bound via a GG spacer. HPMA copolymer-NP-ADR conjugates possessed specific cytotoxicity to T- and B-malignant cells. Concentrations, which were lethal to the latter, were not toxic for PBL.


CONCLUSIONS
The data obtained seem to indicate the potential of the HPMA copolymer-NP conjugates as polymer anticancer drug carriers targetable to immunocompetent cells.
Omelyanenko
V
V
Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City 84112, USA.
Kopecková
P
P
Prakash
R K
RK
Ebert
C D
CD
Kopecek
J
J
D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology; D002051:Burkitt Lymphoma / Q000188:drug therapy / Q000276:immunology; D004317:Doxorubicin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000633:toxicity; D004337:Drug Carriers; D018985:Epitopes, B-Lymphocyte / Q000276:immunology* / Q000378:metabolism; D018984:Epitopes, T-Lymphocyte / Q000276:immunology* / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D018796:Immunoconjugates / Q000276:immunology* / Q000378:metabolism / Q000493:pharmacokinetics / Q000633:toxicity; D007700:Kinetics; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000188:drug therapy / Q000276:immunology; D008214:Lymphocytes / Q000187:drug effects / Q000276:immunology*; D009842:Oligopeptides / Q000008:administration & dosage / Q000276:immunology* / Q000493:pharmacokinetics; D011109:Polymethacrylic Acids / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000633:toxicity; D017464:Receptors, Complement 3d / Q000276:immunology* / Q000378:metabolism; D013329:Structure-Activity Relationship; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D014407:Tumor Cells, Cultured
D004337:Drug Carriers; D018985:Epitopes, B-Lymphocyte; D018984:Epitopes, T-Lymphocyte; D018796:Immunoconjugates; D009842:Oligopeptides; D011109:Polymethacrylic Acids; D017464:Receptors, Complement 3d; C055176:doxorubicin-N-(2-hydroxypropyl)methacrylamide copolymer conjugate; D004317:Doxorubicin