The Effects of T Follicular Helper (TFH) Cells on Anti-FVIII Antibody Formation Öffentlichkeit

Abstract

The development of anti-factor VIII (FVIII) antibodies or inhibitors represents a significant barrier to FVIII replacement therapy in patients with hemophilia A. Despite this, the immune factors that regulate anti-FVIII antibody formation remain incompletely understood. We have previously shown that marginal zone (MZ) B cells are an important initiating factor in the immune response to FVIII. MZ B cell responses can be CD4+ T cell independent or dependent. Additionally, we have previously shown that anti-FVIII antibody formation is a CD4+ T cell dependent process, and it is known that T follicular helper (TFH) cells interact with follicular B cells to produce antibodies in the germinal center (GC) of the spleen. Therefore, we hypothesize that TFH cells play a crucial role in anti-FVIII inhibitor formation. To investigate this hypothesis, we challenged B6 mice with 1-4 weekly doses of FVIII and utilized a FVIII MHC class II tetramer to determine the kinetics of FVIII-specific CD4+ T cell expansion as well as characterize the CD4+ T cell response. In addition, we utilized a conditional knock out (KO) mouse model (TFH KO), which lack the ability to generate TFH cells, to analyze the contribution of TFH cells in anti-FVIII antibody formation. The TFH KO mice and wild type control B6 mice received 4 weekly doses of FVIII and anti-FVIII IgM and IgG in plasma were examined by an enzyme-linked immunoassay (ELISA). Lastly, a Bcl-6 inhibitor, an inhibitor that prevents Bcl-6 expression and thereby should prevent TFH formation, was used to investigate the primary stages for a therapeutic intervention against FVIII inhibitors. B6 mice received an infusion of sheep red blood cells (SRBCs), which have been shown to initiate a GC B cell response, and then were administered the inhibitor, twice daily for 7 days. We found that FVIII specific TFH cells expand after 2-3 exposures to FVIII, TFH cells are necessary for anti-FVIII IgG formation, and 79-6 prevented GC B cell expansion when exposed to a blood-borne antigen. In summary, our present findings and future work will likely reveal important pathways to effectively understand and target anti-FVIII antibody production.

Table of Contents

                                                                        

1.        Introduction                                                                                                               1

2.        Experimental Aims/Goals                                                                                        7

3.        Materials & Methods                                                                                                9

4.        Statistics                                                                                                                    15

5.        Results                                                                                                                        16

6.        Discussion                                                                                                                  22

7.        Figures                                                                                                                        26

8.        References                                                                                                                  35

 

About this Honors Thesis

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School	Emory College
Department	Biology
Degree	B.A.
Submission	Honors Thesis
Language	English
Research Field	Health Sciences, Immunology Health Sciences, Pathology
Stichwort	Hematology Biology Immunology Hemophilia
Committee Chair / Thesis Advisor	Patricia E. Zerra, MD, Emory University
Committee Members	Robert C. Liu, PhD, Emory University Seema R. Patel, PhD, Emory University

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