Immune system: maturation of myeloid cells.

Human and animal cell lines are important laboratory tools that can be used for studying a variety of cell functions. Some cell lines are blocked at a certain step of maturation and can be used in order to study the mechanisms involved in cell maturation. Because such cell lines can be differentiated toward a more mature-like phenotype after the addition of agents, they can replace primary cells in large screening experiments preventing daily isolation. The human promyelocytic HL-60 leukemia cell line is an attractive model for studying the events which occur in myeloid cells. Interestingly, these cells can be differentiated toward monocytes, macrophages, or granulocytes as described in the present chapter.