There are many studies conducted using THP-1 monocytes and maturing them into macrophages, but within protocols, many inconsistencies arise with cell density and PMA concentration. This results in little reliability and validity amongst all research, therefore, it is hypothesized that differing cell densities with different PMA concentrations effect cytokine release of M1 and M2 macrophages. By using ELISA, it is observed that lower densities with higher concentrations of PMA release the most TGF-b which creates controversy. This highlights the importance of finding optimal culturing conditions for better research.