Characterization of mouse bone marrow-derived macrophages differentiated in L929 cell conditioned medium and colony stimulating factor-1 in Listeria monocytogenes in-fection

Abstract

Mouse bone marrow-derived macrophages (BMDM) have been identified as an important host cell model for studying mammalian macrophage functions during pathogen infection. Whereas colony stimulating factor (CSF)-1 is required for BMDM differentiation, the commercial CSF-1, however, is expensive. Therefore, L929 cell-conditioned medium (LCM) has been reported to be used as a source of CSF-1 in many recent studies. However, whether BMDM differentiated by commercial CSF-1 and LCM had any functional differences in bacterial infection, particularly Listeria monocytogenes (LM) infection, has remained unexplored. This study aimed to examine the morphology of macrophages differentiated from CSF-1 and LCM as well as the phagocytic function of these macrophages in LM infection. Mouse bone marrow cells were differentiated in CSF-1 or LCM through 6 days before infected by LM. Phagocytotic roles of BMDM were evaluated throug the capability of macrophages to take up the bacteria, as shown by infection assay and immunofluorescence microscope. The results showed that macrophages grown in CSF-1 and LCM were similar in morphology and phagocytic functions during LM infection. Macrophages from LCM-supplemented media were homogenous and obtained CD11b and F4/80 surface markers. Immunofluorescence images demonstrated that bone marrow-derived macrophages were able to successfully take up LM at 0.5 h but unable to control intracellular bacterial replication by 4 h post infection.