Soluble MHC-peptide complexes containing long rigid linkers abolish CTL-mediated cytotoxicity.
Soluble MHC-peptide (pMHC) complexes induce intracellular calcium mobilization, diverse phosphorylation events, and death of CD8+ CTL, given that they are at least dimeric and co-engage CD8. By testing dimeric, tetrameric, and octameric pMHC complexes containing spacers of different lengths, we show that their ability to activate CTL decreases as the distance between their subunit MHC complexes increases. Remarkably, pMHC complexes containing long rigid polyproline spacers (> or =80 A) inhibit target cell killing by cloned S14 CTL in a dose- and valence-dependent manner. Long octameric pMHC complexes abolished target cell lysis, even very strong lysis, at nanomolar concentrations. By contrast, an altered peptide ligand antagonist was only weakly inhibitory and only at high concentrations. Long D(b)-gp33 complexes strongly and specifically inhibited the D(b)-restricted lymphocytic choriomeningitis virus CTL response in vitro and in vivo. We show that complications related to transfer of peptide from soluble to cell-associated MHC molecules can be circumvented by using covalent pMHC complexes. Long pMHC complexes efficiently inhibited CTL target cell conjugate formation by interfering with TCR-mediated activation of LFA-1. Such reagents provide a new and powerful means to inhibit Ag-specific CTL responses and hence should be useful to blunt autoimmune disorders such as diabetes type I.
Angelov
Georgi S
GS
Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, 1066 Epalinges, Switzerland.
Guillaume
Philippe
P
Cebecauer
Marek
M
Bosshard
Giovanna
G
Dojcinovic
Danijel
D
Baumgaertner
Petra
P
Luescher
Immanuel F
IF
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D016923:Cell Death; D002478:Cells, Cultured; D003432:Cross-Linking Reagents / Q000737:chemistry; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D019281:Dimerization; D006649:Histocompatibility Antigens / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism; D051379:Mice; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D012995:Solubility; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
D003432:Cross-Linking Reagents; D006649:Histocompatibility Antigens; D016169:Lymphocyte Function-Associated Antigen-1; D010446:Peptide Fragments; D010455:Peptides; C011083:polyproline; D002118:Calcium