Differentiation of U-937 Monocytes to Macrophage-Like Cells Polarized into M1 or M2 Phenotypes According to Their Specific Environment: A Study of Morphology, Cell Viability, and Cd Markers of an In Vitro Model of Human Macrophages
Gerald Alter (Committee Member), Nancy Bigley (Advisor), Barbara Hull (Advisor)
Master of Science (MS)
In this study, the human leukemic monocyte lymphoma cell line U-937 was used as an in vitro model for monitoring monocyte/macrophage differentiation. Phorbol 12- myristate (13) (PMA) was used to activate U-937 cells into macrophage-like cells (M0). After 24 hours of PMA treatment, non- adherent U-937 cells became tightly adherent to the culture plates forming M0 cells. M0 cells were then polarized into the M1 macrophage phenotype by treatment with LPS and IFN-γ for another 24 hours. Each of the cytokines IL-4, IL-13, or IL-10 was applied separately to three M0 cultures for 24 hours to induce the M2 macrophage phenotype. M1 and M2 phenotypes displayed distinct morphological characteristics. M1 cells appeared large, with cellular processes (pseudopodia), and intracellular vacuoles while the M2 cells large aggregated into large masses. The undifferentiated U--937 cells expressed less CD206 and CD86 but greater amounts of CD163, CD80, and CD200R than did the differentiated U937 cells (M0 macrophages). These observations suggest that the differentiated M0 cells would be better at antigen presentation since they expressed a 6-fold increase the CD86 costimulatory molecule and half the amount of the CD80 costimulatory molecule as did undifferentiated U937 cells. M1 polarized macrophages expressed lesser amounts of CD14, CD86, CD80, CD163, CD206, and CD200R than M0 cells which may reflect the production of toxic substances such as reactive oxygen molecules, nitric oxide and TNF-a. Both the differentiation and polarization processes caused decreases in cell viability no difference seen between M0 and M1 populations at the 24 hour observation time. Marked differences in expression of these CD markers were obvious in the M2 subpopulations with the IL-4-polarized M2 cell showing marked elevations in expression of CD206 and CD86 and the IL-13-polarized M2 cells showing marked increase in expression of CD14. These differences highlight the plasticity of the macrophage in different microenvironments and may be useful in interpreting experimental results in other systems.
Department or Program
Microbiology and Immunology
Year Degree Awarded
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