title: The role of CD8+CD28 regulatory cells in suppressing myasthenia gravis-associated responses by a dual altered peptide ligand.
abstract: Myasthenia gravis (MG) and experimental autoimmune MG are T cell-dependent antibody-mediated autoimmune diseases. A dual altered peptide ligand (APL), composed of the tandemly arranged two single amino acid analogs of two myasthenogenic peptides, p195-212 and p259-271, down-regulated in vitro and in vivo MG-associated T cell responses. In the present study, we investigated the role of CD8(+)CD28(-) regulatory cells in the mechanism of action of the dual APL. We demonstrated that treatment of mice with the dual APL concomitant with immunization with a myasthenogenic peptide resulted in an increased population of CD8(+)CD28(-) cells that express forkhead box P3 (Foxp3). The dual APL inhibited the proliferation of lymph node (LN) cells of the Torpedo acetylcholine receptor-immunized WT C57BL/6 mice, whereas the inhibition was abrogated in CD8(-/-) knockout mice. Moreover, the dual APL did not inhibit the secretion of IFN-gamma by LN cells from CD8(-/-) mice immunized with Torpedo acetylcholine receptor. However, the mRNA expression of IL-10 and TGF-beta by LN cells from CD8(-/-) mice was up-regulated similarly to that of the WT mice. Furthermore, the dual APL elevated the proapoptotic markers caspases 3 and caspase 8, whereas it down-regulated the antiapoptotic marker Bcl-xL in both CD8(-/-) and WT mice. Finally, the dual APL-induced CD4(+)CD25(+)Foxp3(+) cells were up-regulated in CD8(-/-) mice to a similar extent to that observed in the WT mice. Thus, we suggest that CD8(+)CD28(-) regulatory cells play a partial role in the mechanism of action by which the dual APL suppresses experimental autoimmune MG-associated T cell responses.
authors.affiliation: Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Hava
authors.initials: H
authors.lastname: Ben-David
authors.forename: Amir
authors.initials: A
authors.lastname: Sharabi
authors.forename: Molly
authors.initials: M
authors.lastname: Dayan
authors.forename: Michael
authors.initials: M
authors.lastname: Sela
authors.forename: Edna
authors.initials: E
authors.lastname: Mozes
mesh_terms: D000818:Animals; D018106:CD28 Antigens / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D016827:CD8 Antigens / Q000235:genetics / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D015536:Down-Regulation; D005260:Female; D051858:Forkhead Transcription Factors / Q000378:metabolism; D007114:Immunization; D016753:Interleukin-10 / Q000378:metabolism; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D008024:Ligands; D051379:Mice; D018345:Mice, Knockout; D009157:Myasthenia Gravis / Q000276:immunology / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000276:immunology; D014101:Torpedo / Q000276:immunology; D016212:Transforming Growth Factor beta / Q000378:metabolism; D015854:Up-Regulation; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: D018106:CD28 Antigens; D016827:CD8 Antigens; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D053645:Interleukin-2 Receptor alpha Subunit; D008024:Ligands; D010455:Peptides; D011978:Receptors, Nicotinic; D016212:Transforming Growth Factor beta; D051020:bcl-X Protein; D016753:Interleukin-10; D053148:Caspase 3; D053181:Caspase 8