Figure 2.

(A) Classical activation of bone marrow cells occurs in response to pathogen signals, mainly in the form of Toll-like receptor (TLR) ligands, various damage-related molecular pattern (DAMP) and pathogen-associated molecular pattern (PAMP) molecules. This results in rapid activation of monocytes and neutrophils in the bone marrow, a significant increase in phagocytosis, respiratory bursts, production of pro-inflammatory cytokines and upregulation of major histocompatibility complex (MHC) class II and costimulatory molecules. (B) In chronic infections and cancer, Immature cell differentiation is blocked. They exhibit relatively weak phagocytic activity, increased levels of reactive oxygen species (ROS) and nitric oxide (NO) production, arginase and PGE2, promoting tumor growth. Promotion: →, Inhibition: ┤.