An interleukin-2-IgG-Fas ligand fusion protein suppresses delayed-type hypersensitivity in mice by triggering apoptosis in activated T cells as a novel strategy for immunosuppression.
BACKGROUND
Cell-mediated immune responses can be down-regulated by induction of apoptosis of immunoreactive lymphocytes. In the present study, we have tested the feasibility of a strategy for immunosuppression by the selective induction of apoptosis in activated, interleukin (IL)-2 receptor-positive lymphocytes, using a triple IL-2-IgG-FasL fusion protein. The IL-2-IgG-FasL fusion protein combines IL-2 for the selection of activated T cells, with the extracellular domain of the FasL molecule for inducing T-cell apoptosis. These components were separated by the Fc part of IgG1 serving as a spacer as well as for half-life prolongation.


METHODS
The gene for the chimeric protein was created by fusing DNA sequences encoding for the three functional components: human IL-2, the Fc part of human IgG1, and the extracellular domain of murine FasL. When the fusion gene was expressed in murine J558L cells, we obtained soluble dimeric immunoglobulin-like proteins in the supernatant. After analyzing the function of the IL-2 and FasL portions individually in vitro, a delayed-type hypersensitivity (DTH) reaction to sheep red blood cells as model for cell-mediated immune responses was investigated to evaluate the IL-2-IgG-FasL-mediated immunosuppression in vivo.


RESULTS
In vitro, the IL-2-IgG-FasL fusion protein supported IL-2-dependent proliferation of Fas-resistant CTLL-2 cells, whereas concanavalin A-T blasts were induced to undergo apoptosis by the FasL portion. In vivo, this fusion protein potently inhibited a murine DTH. This was associated with an increased rate of apoptosis in activated lymphocytes in the spleen, even at very low doses of the fusion protein. Furthermore, a second antigen challenge 10 days after IL-2-IgG-FasL treatment still failed to elicit a DTH response.


CONCLUSIONS
The abrogation of a standard T cell-dependent immune response in vivo demonstrates that IL-2-IgG-FasL can be successfully exploited to trigger the death of deleterious T cells, presenting a potentially useful strategy in the management of autoimmune diseases and allotransplant rejections.
Bulfone-Paus
S
S
Institute of Immunology and Department of Urology, University Hospital Benjamin Franklin, Free University Berlin, Germany.
Rückert
R
R
Krause
H
H
von Bernuth
H
H
Notter
M
M
Pohl
T
T
Tran
T H
TH
Paus
R
R
Kunzendorf
U
U
D000818:Animals; D017209:Apoptosis; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D053222:Fas Ligand Protein; D005240:Feasibility Studies; D006801:Humans; D006968:Hypersensitivity, Delayed / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D007141:Immunoglobulin Fc Fragments / Q000235:genetics; D007074:Immunoglobulin G / Q000235:genetics*; D007165:Immunosuppression Therapy / Q000379:methods*; D007376:Interleukin-2 / Q000235:genetics*; D008099:Liver / Q000473:pathology; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D011993:Recombinant Fusion Proteins / Q000627:therapeutic use*; D012756:Sheep / Q000097:blood; D013154:Spleen / Q000473:pathology; D013601:T-Lymphocytes / Q000187:drug effects / Q000502:physiology; D013950:Thymus Gland / Q000473:pathology
C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007376:Interleukin-2; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins