Browsing publications of the research group system immunology ([BRICS]SIMM) by Subjects
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Computer Simulation of Multi-Color Brainbow Staining and Clonal Evolution of B Cells in Germinal Centers.Clonal evolution of B cells in germinal centers (GCs) is central to affinity maturation of antibodies in response to pathogens. Permanent or tamoxifen-induced multi-color recombination of B cells based on the brainbow allele allows monitoring the degree of color dominance in the course of the GC reaction. Here, we use computer simulations of GC reactions in order to replicate the evolution of color dominance
Injection of Antibodies against Immunodominant Epitopes Tunes Germinal Centers to Generate Broadly Neutralizing Antibodies.Broadly neutralizing antibodies are crucial for the control of many life-threatening viral infections like HIV, influenza, or hepatitis. Their induction is a prime goal in vaccine research. Using computer simulations, we identify strategies to promote the generation of broadly neutralizing antibodies in natural germinal center (GC) reactions. The simulations predict a feedback loop based on antibodies and memory B cells from previous GC reactions that promotes GCs to focus on new epitopes. Memory-derived or injected antibodies specific for immunodominant epitopes control epitope availability, suppress the participation of memory B cells in the GC reaction, and allow for the evolution of other B cells to affinity mature for hidden or rare epitopes. This defines a natural selection mechanism for GC B cells to concentrate on new epitopes rather than refine affinity to already-covered epitopes. This principle can be used for the design and testing of future therapies and vaccination protocols.
Synchronous Germinal Center Onset Impacts the Efficiency of Antibody Responses.The germinal center reaction is an important target for modulating antibody responses. Antibody production from germinal centers is regulated by a negative feedback mechanism termed antibody feedback. By imposing antibody feedback, germinal centers can interact and regulate the output of other germinal centers. Using an agent-based model of the germinal center reaction, we studied the impact of antibody feedback on kinetics and efficiency of a germinal center. Our simulations predict that high feedback of antibodies from germinal centers reduces the production of plasma cells and subsequently the efficiency of the germinal center reaction by promoting earlier termination. Affinity maturation is only weakly improved by increased antibody feedback and ultimately interrupted because of premature termination of the reaction. The model predicts that the asynchronous onset and changes in number of germinal centers could alter the efficiency of antibody response due to changes in feedback by soluble antibodies. Consequently, late initialized germinal centers have a compromised output due to higher antibody feedback from the germinal centers formed earlier. The results demonstrate potential effects of germinal center intercommunication and highlight the importance of understanding germinal center interactions for optimizing the antibody response, in particular, in the elderly and in the context of vaccination.