title: Anti-CD3 prevents factor VIII inhibitor development in hemophilia A mice by a regulatory CD4+CD25+-dependent mechanism and by shifting cytokine production to favor a Th1 response.
abstract: Non-Fc-receptor binding anti-CD3 Ab therapy, in the setting of several different autoimmune disorders, can induce antigen-specific and long-lasting immunologic tolerance. Because factor VIII (FVIII) inhibitor formation is the most serious treatment-related complication for hemophilia A patients, we tested the efficacy of anti-CD3 to prevent FVIII inhibitor formation in hemophilia A BALB/c and C57BL/6 mice. A short course of low-dose anti-CD3 significantly increased expression of CD25 and the proportion of CD4+CD25+ regulatory T cells in the spleen and potently prevented the production of inhibitory and non-neutralizing anti-FVIII antibodies in both strains of mouse. Depleting the CD4+CD25+ cells during anti-CD3 therapy completely ablated tolerance to FVIII. Further phenotypic characterization of regulatory cells in tolerant mice showed a consistently higher number of CD4+GITR+ and CD4+FoxP3+ cells in both strains of mice. In addition, in tolerant C57BL/6 mice we observed an increase in CD4+CD25+ CTLA-4+ and CD4+CD25+mTGF-beta1+ cells. Finally, in vitro cytokine profiling demonstrated that splenocytes from tolerant BALB/c and C57BL/6 were polarized toward a Th1-immune response. Taken together, these findings indicate that anti-CD3 induces tolerance to FVIII and that the mechanism(s) regulating this response almost certainly occurs through the generation of several distinct regulatory T-cell lineages and by influencing cytokine production and profile.
authors.affiliation: Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada.
authors.forename: Braden
authors.initials: B
authors.lastname: Waters
authors.forename: Mohammad
authors.initials: M
authors.lastname: Qadura
authors.forename: Erin
authors.initials: E
authors.lastname: Burnett
authors.forename: Rouzbeh
authors.initials: R
authors.lastname: Chegeni
authors.forename: Andrea
authors.initials: A
authors.lastname: Labelle
authors.forename: Patrick
authors.initials: P
authors.lastname: Thompson
authors.forename: Christine
authors.initials: C
authors.lastname: Hough
authors.forename: David
authors.initials: D
authors.lastname: Lillicrap
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology*; D017252:CD3 Complex / Q000276:immunology*; D015704:CD4 Antigens / Q000378:metabolism; D019070:Cell Lineage / Q000276:immunology; D005169:Factor VIII / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000494:pharmacology*; D005260:Female; D006467:Hemophilia A / Q000188:drug therapy* / Q000235:genetics / Q000276:immunology*; D007108:Immune Tolerance / Q000276:immunology; D016130:Immunophenotyping; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D013154:Spleen / Q000166:cytology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000378:metabolism; D018417:Th1 Cells / Q000276:immunology* / Q000378:metabolism
chemical_list: D000906:Antibodies; D017252:CD3 Complex; D015704:CD4 Antigens; C485468:Cd3e protein, mouse; D053645:Interleukin-2 Receptor alpha Subunit; D005169:Factor VIII