Explain the molecular mechanism that stimulate interactions between Follicular dendritic cells and B lymphocytes.?

FDC cells secrete chemokines that bind CXCR5 receptors on naïve B lymphocyte and attract them to germinal centers. After exposure to antigen B and T lymphocytes loose expression of CXCR5 and CCR7 receptors and migrate toward each other at the edge of follicles. Interaction between T and B lymphocytes stimulates differentiation of B lymphocytes into antibodies-producing plasma cells and memory cells (Ch7). Plasma cells stay in lymph nodes or migrate to bone marrow