Mouse placental macrophages have a decreased ability to present antigen.

Large numbers of macrophages can be found in an animal's uteroplacental unit. This high concentration of macrophages suggests they must play an important role during placental development. To gain a better understanding of the functional capacity of placental macrophages, we have obtained a highly enriched placental macrophage culture and have derived several cell lines from this population. Both placental macrophages and cell lines show colony-stimulating factor 1-dependent growth, express Fc receptors, and can perform Fc-receptor-mediated phagocytosis. In addition, they express macrophage markers Mac-1, F4/80, and CD14. Although placental macrophages express major histocompatibility complex class II molecules constitutively, they display a decreased ability to present protein antigens to T cells. Since primary fetal liver macrophages of the same gestational stage also show a decreased ability to present antigens, this phenomenon may reflect a developmental stage of macrophages.