Immortalized HK/FDC Cells

The immortalized HK/FDC cell line is a genetically stabilized derivative of the original HK follicular dendritic cell-like cells, retaining key phenotypic and functional characteristics while enabling extended propagation without the senescence-associated limitations of the parental culture. Immortalization was achieved through the introduction of defined genetic elements that bypass replicative arrest, facilitating consistent long-term studies of germinal center biology and FDC–B cell interactions. Immortalized HK/FDC cells maintain the capacity to bind and co-stimulate germinal center B cells, promote their survival, and enhance their proliferation in the presence of signals such as anti-IgM or CD40 ligation. Importantly, they continue to express adhesion molecules and costimulatory factors characteristic of FDCs, including VCAM-1 and ICAM-1, and secrete soluble mediators that mimic the microenvironmental support provided by native FDCs. These properties make the immortalized HK/FDC line a robust and reproducible model for dissecting the cellular and molecular mechanisms governing B cell maturation, affinity selection, and survival within the germinal center.