How antigens (and pathogens) enter the B cell follicles of secondary lymphoid tissues and are acquired by B cells has been a long-standing enigma. However, recent papers have identified at least two major pathways in which lymph-borne antigens enter the B cell area and are either acquired by cognate B cells or retained on follicular dendritic cells (FDC). Importantly, the nature of the antigen is a major factor. While small soluble antigens enter via a network of conduits formed by fibroblast reticular cells, larger protein immune complexes and particulate antigens are bound by subcapsular sinus macrophages and shuttled to the underlying B cells where they are captured by cognate B or bound by naive B cells via CD21 receptor. How the antigen is transferred to the FDC remains unclear. Most recently, we reported a third pathway in which lymph-borne influenza (UV-inactivated) was rapidly opsonized via mannan binding lectin and bound by macrophages lining both the subcapsular sinus and the medullary regions. Notably, macrophages are not required for humoral immunity in this pathway. Instead, dendritic cells residing in the medullary region of the LN capture virus via SIGN-R1 and appear to directly transport the viral particles to the B cell area. Whether the virus is handed off directly to FDC or to other intermediates in the follicles is not known. The overall goal of this proposal is to clarify how B cell antigen is delivered and off-loaded onto the FDC surface.
Two aims are proposed. (1) Test the hypothesis that B cells transfer antigen to FDC in a 3-step process. (2) Test the hypothesis that LN resident mDC capture antigens via SIGN-R1 and traffick to FDC. )
Understanding where and how B cells acquire cognate antigen is of fundamental importance from both the point of view of host protection and autoimmunity. The ability to observe antigen draining into LNs directly and to determine how they are eventually acquired in real time by B cells provides a novel insight unattainable by traditional immunization methods. From a practical view, this approach could be used to develop more efficient vaccines by targeting pathogens to a specific site within the LN or spleen.
|Degn, Søren E; van der Poel, Cees E; Firl, Daniel J et al. (2017) Clonal Evolution of Autoreactive Germinal Centers. Cell 170:913-926.e19|
|Heesters, Balthasar A; Carroll, Michael C (2016) The Role of Dendritic Cells in S. pneumoniae Transport to Follicular Dendritic Cells. Cell Rep 16:3130-3137|
|Jafarnejad, Mohammad; Woodruff, Matthew C; Zawieja, David C et al. (2015) Modeling Lymph Flow and Fluid Exchange with Blood Vessels in Lymph Nodes. Lymphat Res Biol 13:234-47|
|Astarita, Jillian L; Cremasco, Viviana; Fu, Jianxin et al. (2015) The CLEC-2-podoplanin axis controls the contractility of fibroblastic reticular cells and lymph node microarchitecture. Nat Immunol 16:75-84|
|Zhao, Fan; Heesters, Balthasar A; Chiu, Isaac et al. (2014) L-Rhamnose-containing supramolecular nanofibrils as potential immunosuppressive materials. Org Biomol Chem 12:6816-9|
|Heesters, Balthasar A; Myers, Riley C; Carroll, Michael C (2014) Follicular dendritic cells: dynamic antigen libraries. Nat Rev Immunol 14:495-504|
|Dwyer, Daniel F; Woodruff, Matthew C; Carroll, Michael C et al. (2014) B cells regulate CD4+ T cell responses to papain following B cell receptor-independent papain uptake. J Immunol 193:529-39|
|Heesters, Balthasar A; Das, Abhishek; Chatterjee, Priyadarshini et al. (2014) Do follicular dendritic cells regulate lupus-specific B cells? Mol Immunol 62:283-8|
|Woodruff, Matthew C; Heesters, Balthasar A; Herndon, Caroline N et al. (2014) Trans-nodal migration of resident dendritic cells into medullary interfollicular regions initiates immunity to influenza vaccine. J Exp Med 211:1611-21|
|Chatterjee, Priyadarshini; Agyemang, Amma F; Alimzhanov, Marat B et al. (2013) Complement C4 maintains peripheral B-cell tolerance in a myeloid cell dependent manner. Eur J Immunol 43:2441-2450|
Showing the most recent 10 out of 33 publications