The Choice between M1 or M2 macrophages for U937

One of the most well-known innate immune cells is the M1 and M2 macrophages both derive from monocytes, which are white blood cells. M1 macrophages are activated by IFN-γ or lipopolysaccharide products and induce a pro-inflammatory response, which triggers the inflammation in multiple areas such as the brain or lungs. This macrophage contains extracellular vehicles (EVs) that carry pro-inflammatory cytokines such as TNF-α. M2 macrophages are activated by IL-4 and IL-13 products, and this macrophage induces anti-inflammatory responses and influences wound healing. This macrophage can reduce inflammation in the brain and lungs. In this study, we were given U937 which is a cell line derived histiocytic lymphoma and CEM which are t-cells. These cells can differentiate into macrophages or dendritic cells, and the aim is to determine which macrophage U937 would fall into, which is M1 or M2. The CEM and U937 cells were treated with lipopolysaccharide (endotoxin), and the cells were observed under a microscope for 2 days. EVs were isolated from both cells, followed by a Western blot. After transferring the proteins onto a membrane via gel electrophoresis, primary and secondary antibodies such as CD63-rabbit and secondary anti-rabbit were introduced. CD81-RB and secondary rabbit were introduced reveal whether any CD81 proteins present. TNF- α, an M1 marker for macrophages, and CD11b, an M2 marker, were introduced to the membrane and then imaged. Imaging revealed CD63, CD81, CD11B were detected, while TNF- α was inconclusive. Overall, the U937 leans towards an M2 marker rather than an M1 marker.