RESUMEN
To delineate the individual role of follicular dendritic cells (FDC) and T cells at each stage of GC B cell differentiation at the clonal level and to analyze the signals required for the differentiation, we developed an experimental model using an FDC line, HK and a lymphoma cell line, L3055 for centroblasts. Phenotypic analysis of L 3055 revealed its origin of GC and the homogeneity. L3055 cells undergo spontaneous apoptosis when cultured in the absence of HK cells. L3055 cells proliferate continuously in the presence of HK cells, while they differentiate into a population with the phenotype of centrocytes after stimulation with CD40 ligand (CD 40L) plus IL-2, IL-4 and IL-10. L3055 undergo anti-Ig-mediated apoptosis, which is not protected by HK but by CD40L and the cytokines. These experimental results suggest that FDC provide signals for the survival and rapid proliferation of centroblasts and T cells trigger the differentiation of centroblasts into centrocytes.