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RGD‐modified anti‐CD3 antibodies redirect cytolytic capacity of cytotoxic T lymphocytes toward α v β 3 ‐expressing endothelial cells
Author(s) -
Schraa Astrid J.,
Kok Robbert J.,
Botter Sander M.,
Withoff Sebo,
Meijer Dirk K.F.,
de Leij Lou F.M.H.,
Molema Grietje
Publication year - 2004
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.20413
Subject(s) - ctl* , microbiology and biotechnology , cd3 , cytotoxic t cell , jurkat cells , cytotoxicity , biology , antibody , chemistry , t cell , antigen , in vitro , biochemistry , immunology , immune system , cd8
To redirect the lytic activity of cytotoxic T lymphocytes (CTL) toward tumor vascular endothelial cells, we prepared bifunctional proteins with specificity for both α v β 3 and CD3. Monocyclic RGD peptides (cRGDfK) were covalently coupled to an anti‐CD3 monoclonal antibody at different peptide:protein ratios. The resulting RGDpep‐anti‐CD3 conjugates bound specifically to α v β 3 ‐expressing endothelial cells. Displacement studies with radiolabeled α v β 3 ligand demonstrated that the α v β 3 binding affinity of RGDpep‐anti‐CD3 conjugates was elevated as compared to the non‐conjugated RGDpep. IC 50 values ranged from 150–1.1 nM, depending on the amount of coupled RGDpep molecules per antibody molecule. RGD modification did not affect the ability of anti‐CD3 antibodies to bind to CTL. Furthermore, RGDpep‐anti‐CD3 was fully capable of activating T cells upon CD3 binding as was shown in a Jurkat/NFAT reporter‐gene activation assay. All RGDpep‐anti‐CD3 conjugates were able to induce RGDpep, CD3‐dependent lysis of human primary endothelial cells by anti‐CD3/IL‐2 activated human peripheral blood mononuclear cells (PBMC), with a significant induction of cytotoxicity observed at an E/T ratio as low as 10. Redirecting cytolytic activity reached up to 50% cytotoxicity using the conjugate with the highest RGD peptide load. Combining the good accessibility of tumor blood vessel endothelium for CTL with the efficiency of target cell killing warrants further investigations on anti‐tumor effects of this type of conjugates in vivo . © 2004 Wiley‐Liss, Inc.