PhD Scientific Days 2026

Poster Session 2.C - Molecular Medicine

Characterization and Development of Bursal Secretory Dendritic Cells Using Transgenic and Embryomanipulation Techniques

Name of the presenter

Szőcs, Emőke

Institute/workplace of the presenter

Department of Anatomy, Histology and Embryology

Authors

Emőke Szőcs¹, Stefánia-Zsófia Bogya¹, Ádám Soós¹, Viktória Halasy¹, Nándor Nagy¹
1: Department of Anatomy, Histology and Embryology, Semmelweis University

Text of the abstract

Introduction: The bursa of Fabricius (BF) is a primary lymphoid organ characteristic of birds that plays an indispensable role in B-cell maturation and the development of the antigen-specific immune response. Reticular epithelial cells and bursal secretory dendritic cells (BSDC) located within the lymphoid follicles of the BF provide a selective microenvironment for B-cell proliferation and differentiation. In contrast to the supportive epithelial cells, the ontogeny, immunophenotype, and function of BSDCs are only partially understood.
Aims and methods: Our aim is to characterize the lymphoid and myeloid cells in bursal lymphoid follicles, identify membrane markers that can be selectively used for the labeling of BSDCs. Using transgenic and embryomanipulation techniques we aim to understand the ontogeny and fate of BSDCs.
Results: We demonstrate that within the lymphoid follicles of the BF alongside E-cadherin+ epithelial cells, chB6+ B-cells, and TIMD4+/Lamp1+ macrophages CSF1R selectively labels BSDCs during both embryonic and adult stages. Using bursa of Fabricius samples isolated from wild-type and CSF1R-eGFP transgenic chickens, we confirmed that CSF1R+ BSDCs express CD11d, p75-neurotrophin receptor and alphaV/beta3 integrin. Using immunoelectron microscopy, we provided the first evidence that the CSF1R+/p75+ dendritic cells localized in the follicular medulla and the TIMD4+/Lamp1+ macrophages represent distinct cell populations. RNAscope in situ hybridization assays confirmed that CSF1R+ BSDCs immigrating during the ontogeny of the BF express the CXCL13 chemokine following the colonization of follicular primordia. This chemokine is responsible for the subsequent follicular colonization by B-cell precursors expressing chB6 and CXCR5 receptors.
Conclusion: The identification of BSDC-specific membrane molecules enables the efficient isolation of these cells via fluorescence-activated cell sorting (FACS). This is essential for the molecular characterization of dendritic cells and the development of in vitro functional assays, ultimately contributing to a detailed understanding of B-cell activation and the design of effective vaccines against viral immunosuppressive diseases.

Funding: NKFI K-138664, 2024-2.1.1-EKÖP-2024-00004 University Research Scholarship Programme of The Ministry for Culture and Innovation