Role of hematopoietic growth factors/flt3 ligand in expansion and regulation of dendritic cells

Dendritic cells (DCs) are hematopoietic cells that initiate immune response s by presenting antigen to T cells. Granulocyte-macrophage colony-stimulati ng factor (GM-CSF) is a primary growth factor for DCs in vitro, but recentl y it was recognized that other factors including flt3 ligand (FL) and G-CSF expand various DC subsets in vivo. DCs undergo a complex series of maturat ion and activation steps after they acquire antigen and before they can act ivate resting T cells, In addition, they must traffic to T-cell-rich areas of lymph nodes (LN) to achieve this. Each of these steps is tightly regulat ed, and in the last year progress has been made in identifying some of the key molecules involved in each of these steps. This progress will further t he efforts underway to develop DCs as vaccine adjuvants. (C) 2001 Lippincot t Williams & Wilkins. Inc.