THP-1 cells are a human monocytic leukemia cell line widely used as a model for studying monocyte and macrophage function. They can be differentiated into macrophage-like cells by treatment with phorbol esters such as PMA. THP-1 cells are commonly used in immunological studies, drug screening, and cytotoxicity assays., These cells express various surface markers and receptors characteristic of monocytes and macrophages. They are typically cultured in RPMI 1640 medium supplemented with serum and antibiotics. Cell density and passage number can influence their differentiation potential and functional properties. Typical quantity is 5*10^6 cells/1ml.