Functionally active Epstein-Barr virus-transformed follicular dendritic cell-like cell lines

Area of Science:

• Immunology
• Cell Biology

Background:

• Follicular dendritic cells (FDC) are crucial nonlymphoid cells residing in germinal centers.
• FDC play a vital role in supporting germinal center B cell survival and maturation.
• Establishing immortalized FDC lines is challenging but essential for studying their functions.

Purpose of the Study:

• To establish factor-independent immortalized follicular dendritic cell-like (FDC-like) cell lines.
• To investigate the role of FDC in B cell selection and maturation during germinal center reactions.
• To characterize the phenotype and function of EBV-transformed FDC-like cells.

Main Methods:

• Isolation of FDC-enriched cell populations.
• Transformation of isolated FDC with Epstein-Barr Virus (EBV).
• Characterization of cell lines using morphology, cell surface markers (ICAM-1, CD40, CD75), and EBV-encoded proteins (LMP1, EBNA2).
• Assessment of FDC-like cell ability to bind and rescue nonautologous B cells from apoptosis, examining adhesion molecules (LFA-1/ICAM-1).

Main Results:

• Successful generation of immortalized FDC-like cell lines through EBV transformation.
• These cell lines exhibited fibroblast-like morphology but distinct phenotypes from human fibroblasts.
• FDC-like cells expressed characteristic markers (ICAM-1, CD40, CD75) and EBV proteins (LMP1, EBNA2).
• The FDC-like cells demonstrated the ability to bind B cells and protect them from apoptosis via LFA-1/ICAM-1 mediated adhesion, resembling emperipolesis.

Conclusions:

• Follicular dendritic cells (FDC) can be successfully infected and immortalized by Epstein-Barr Virus (EBV).
• The established EBV-transformed FDC-like cell lines retain key phenotypic and functional characteristics of primary FDC.
• These cell lines serve as a valuable tool for studying FDC-mediated B cell selection and survival in germinal center reactions.