C-reactive protein (CRP) is an acute-phase inflammatory protein that increases significantly at sites of infection or inflammation. It is primarily synthesized in liver hepatocytes but also in other cell types such as smooth muscle cells, macrophages, endothelial cells, lymphocytes, and adipocytes. CRP exists as two isoforms: native CRP (nCRP) and monomeric CRP (mCRP). nCRP is a homopentamer that can irreversibly dissociate into five monomers, which exhibit distinct biological activities. nCRP is more anti-inflammatory, activating the classical complement pathway, inducing phagocytosis, and promoting apoptosis. In contrast, mCRP promotes chemotaxis and recruitment of leukocytes, delays apoptosis, and enhances NO production. The role of CRP in inflammation and infection is multifaceted, including activation of the complement pathway, apoptosis, phagocytosis, NO release, and cytokine production. Early studies often lacked clarity due to the lack of distinction between CRP isoforms and potential contamination with mCRP. Recent research highlights the differential roles of nCRP and mCRP in various inflammatory and infectious conditions, emphasizing the need for further investigation to fully understand their contributions.C-reactive protein (CRP) is an acute-phase inflammatory protein that increases significantly at sites of infection or inflammation. It is primarily synthesized in liver hepatocytes but also in other cell types such as smooth muscle cells, macrophages, endothelial cells, lymphocytes, and adipocytes. CRP exists as two isoforms: native CRP (nCRP) and monomeric CRP (mCRP). nCRP is a homopentamer that can irreversibly dissociate into five monomers, which exhibit distinct biological activities. nCRP is more anti-inflammatory, activating the classical complement pathway, inducing phagocytosis, and promoting apoptosis. In contrast, mCRP promotes chemotaxis and recruitment of leukocytes, delays apoptosis, and enhances NO production. The role of CRP in inflammation and infection is multifaceted, including activation of the complement pathway, apoptosis, phagocytosis, NO release, and cytokine production. Early studies often lacked clarity due to the lack of distinction between CRP isoforms and potential contamination with mCRP. Recent research highlights the differential roles of nCRP and mCRP in various inflammatory and infectious conditions, emphasizing the need for further investigation to fully understand their contributions.