Dendritic cell: A special type of cell that is a key regulator of the immune system, acting as a professional antigen-presenting cell (APC) capable of activating naïve T cells and stimulating the growth and differentiation of B cells.
Dendritic cells are found, for example, in the lymph nodes and spleen. As an APC, a dendritic cell can retain antigen for long periods on its surface, present the antigen to a T or B cell and so influence their behavior.
The word "dendritic" means "branched like a tree." It comes from the Greek "dendron" (tree).