Interleukin-10 drives human monocytes to CD16 positive macrophages

Cells of the monocyte/macrophage lineage are heterogenous in that some types express the CD16 molecule (Fc receptor for IgG, type III), while others are negative. We now show that culture of human blood monocytes with interleukin-10 (IL-10) will induce high levels of cell surface CD16 within 18 hr, and this goes along with increased transcript levels. After prolonged culture for 36 hr, control cultures also become CD16 positive and this induction can be prevented by anti-IL-10, but not by anti-tumor necrosis factor (TNF) antibody or isotype control. In vitro culture of blood monocytes results in a spontaneous decrease of the myelomonocytic stem cell antigen CD33, suggesting that the cells undergo maturation. IL-10 treatment will accelerate this process and result in a further reduction of cell surface CD33. These data indicate that IL-10 promotes monocyte maturation and directs these cells to develop into CD16 positive macrophages.