FD-891, a structural analogue of concanamycin A that does not affect vacuolar acidification or perforin activity, yet potently prevents cytotoxic T lymphocyte-mediated cytotoxicity through the blockage of conjugate formation.
FD-891 belongs to a group of 18-membered macrolides, and is a structural analogue of a specific inhibitor of vacuolar type H+-ATPase, concanamycin A (CMA). In our previous work, we have shown that CMA specifically inhibits perforin-dependent cytotoxic T lymphocyte (CTL)-mediated cytotoxicity through the degradation and inactivation of perforin, although CMA does not affect Fas ligand (FasL)-dependent cytotoxicity. Here, we show that FD-891 potently prevents not only perforin-dependent but also FasL-dependent CTL-mediated killing pathways by blocking CTL-target conjugate formation. In contrast to CMA, FD-891 was unable to inhibit vacuolar acidification and only slightly decreased the perforin activity in lytic granules. FD-891 blocked granule exocytosis in response to anti-CD3, mainly owing to the lack of CTL binding to immobilized anti-CD3. The conjugate formation was markedly inhibited only when effector cells were pretreated with FD-891. Consistent with these observations, fluorescence-activated cell sorter (FACS) analysis for cell surface receptors revealed that FD-891 significantly reduced the expression of the T-cell receptor (TCR)/CD3 complex. These data suggest that the blockage of conjugate formation and subsequent target cell killing might be at least partly owing to FD-891-induced down-regulation of the TCR/CD3 complex.
Kataoka
T
T
Department of Bioengineering, Tokyo Institute of Technology, Midori-ku, Yokohama, Taisho Pharmaceutical Co. Ltd, Ohmiya-shi, Saitama, Japan.
Yamada
A
A
Bando
M
M
Honma
T
T
Mizoue
K
K
Nagai
K
K
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017252:CD3 Complex / Q000378:metabolism; D003602:Cytotoxicity, Immunologic / Q000187:drug effects*; D005089:Exocytosis / Q000187:drug effects; D053222:Fas Ligand Protein; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008024:Ligands; D018942:Macrolides; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects* / Q000276:immunology; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism; D019014:fas Receptor / Q000276:immunology / Q000378:metabolism
D000900:Anti-Bacterial Agents; D017252:CD3 Complex; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008024:Ligands; D018942:Macrolides; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D011948:Receptors, Antigen, T-Cell; D019014:fas Receptor; D054353:Perforin; C091118:FD 891