CD4+ T-cell epitopes associated with antibody responses after intravenously and subcutaneously applied human FVIII in humanized hemophilic E17 HLA-DRB11501 mice

• Published in: Blood Vol. 119; no. 17; pp. 4073 - 4082
• Main Authors: Steinitz, Katharina N., van Helden, Pauline M., Binder, Brigitte, Wraith, David C., Unterthurner, Sabine, Hermann, Corinna, Schuster, Maria, Ahmad, Rafi U., Weiller, Markus, Lubich, Christian, de la Rosa, Maurus, Schwarz, Hans Peter, Reipert, Birgit M.
• Format: Journal Article
• Language: English
• Published: Washington, DC Elsevier Inc 26.04.2012; Americain Society of Hematology
• Subjects: Animals; Antibody Formation - immunology; Antigen Presentation; Biological and medical sciences; CD4-Positive T-Lymphocytes - immunology; CD4-Positive T-Lymphocytes - metabolism; Dendritic Cells - cytology; Dendritic Cells - immunology; Dendritic Cells - metabolism; Disease Models, Animal; Epitopes, T-Lymphocyte - immunology; Factor VIII - administration & dosage; Factor VIII - immunology; Haplotypes - genetics; Hematologic and hematopoietic diseases; Hemophilia A - immunology; Hemophilia A - metabolism; Hemophilia A - pathology; HLA-DRB1 Chains - immunology; HLA-DRB1 Chains - metabolism; Humans; Injections, Intravenous; Injections, Subcutaneous; Male; Medical sciences; Mice; Platelet diseases and coagulopathies; Recombinant Proteins - administration & dosage; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Human; CD4 T lymphocyte; Immune response; Intravenous administration; Antigenic determinant; Hematology; Antibody; Rodentia; Factor VIII; Hemopathy; HLA-DR-Locus; Genetic disease; Vertebrata; Mammalia; Mouse; Animal; Hemophilia; Coagulopathy; Humoral immunity
• ISSN: 0006-4971; 1528-0020; 1528-0020
• DOI: 10.1182/blood-2011-08-374645

Today it is generally accepted that B cells require cognate interactions with CD4+ T cells to develop high-affinity antibodies against proteins. CD4+ T cells recognize peptides (epitopes) presented by MHC class II molecules that are expressed on antigen-presenting cells. Structural features of both the MHC class II molecule and the peptide determine the specificity of CD4+ T cells that can bind to the MHC class II–peptide complex. We used a new humanized hemophilic mouse model to identify FVIII peptides presented by HLA-DRB1*1501. This model carries a knockout of all murine MHC class II molecules and expresses a chimeric murine-human MHC class II complex that contains the peptide-binding sites of the human HLA-DRB1*1501. When mice were treated with human FVIII, the proportion of mice that developed antibodies depended on the application route of FVIII and the activation state of the innate immune system. We identified 8 FVIII peptide regions that contained CD4+ T-cell epitopes presented by HLA-DRB1*1501 to CD4+ T cells during immune responses against FVIII. CD4+ T-cell responses after intravenous and subcutaneous application of FVIII involved the same immunodominant FVIII epitopes. Interestingly, most of the 8 peptide regions contained promiscuous epitopes that bound to several different HLA-DR proteins in in vitro binding assays.