CD95 (Fas) ligand-expressing vesicles display antibody-mediated, FcR-dependent enhancement of cytotoxicity.
Bioactive Fas ligand (FasL)-expressing vesicles were generated (vesicle preparation, VP) from two cell lines overexpressing FasL. The effect of NOK-1 anti-FasL mAb (mouse IgG1) on the cytotoxicity of FasL VP against various targets was determined. At high concentrations (1-10 microg/ml), NOK-1 inhibited the cytotoxicity. By contrast, NOK-1 in the dose range of 1-100 ng/ml significantly enhanced cytotoxicity against the FcR(+) LB27.4, M59, and LF(+) targets, but not the FcR(-) Jurkat and K31H28 hybridoma T cell targets. The ability to enhance FasL VP-mediated cytotoxicity could be blocked by the FcR-specific mAb 2.4G2. Enhancement was also observed with FcR(+) A20 B lymphoma but not with the FcR(-) A20 variant. Enhancement of FasL VP cytotoxicity was observed with five IgG anti-FasL mAbs, but not with an IgM anti-FasL mAb. Inhibition was observed with high doses of all mAb except the IgG anti-FasL mAb G247-4, which is specific to a segment outside the FasL binding site. Interestingly, under identical conditions but in the presence of 2.4G2, G247-4 inhibited the cytotoxicity of FasL VP. In addition, G247-4 inhibited the FasL VP-mediated killing of FcR(-) Jurkat. The data demonstrate that FasL-expressing bioactive vesicles display a property heretofore unknown in bioactive agents that express FasL-mediated cytotoxicity. The mechanism of the Ab-mediated, FcR-dependent enhancement of cytotoxicity of bioactive vesicles and its physiological significance are discussed.
Jodo
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The Arthritis Center, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA.
Hohlbaum
A M
AM
Xiao
S
S
Chan
D
D
Strehlow
D
D
Sherr
D H
DH
Marshak-Rothstein
A
A
Ju
S T
ST
D000276:Adjuvants, Immunologic / Q000502:physiology*; D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000378:metabolism / Q000494:pharmacology; D000918:Antibody Specificity; D000920:Antibody-Dependent Cell Cytotoxicity / Q000276:immunology*; D002460:Cell Line; D002474:Cell-Free System / Q000276:immunology* / Q000378:metabolism; D003601:Cytotoxicity Tests, Immunologic; D053222:Fas Ligand Protein; D006801:Humans; D007074:Immunoglobulin G / Q000235:genetics; D007132:Immunoglobulin Isotypes / Q000502:physiology; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007940:Leukemia L5178; D008024:Ligands; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D051379:Mice; D011961:Receptors, Fc / Q000096:biosynthesis / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000378:metabolism*
D000276:Adjuvants, Immunologic; D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes; D007166:Immunosuppressive Agents; D008024:Ligands; D008562:Membrane Glycoproteins; D011961:Receptors, Fc; D011993:Recombinant Fusion Proteins; D019014:fas Receptor