C-reactive protein (CRP) is an acute-phase inflammatory protein that increases up to 1,000-fold at sites of infection or inflammation. It is produced as a homopentameric protein, native CRP (nCRP), which can dissociate into monomeric CRP (mCRP) at sites of inflammation. CRP is synthesized primarily in liver hepatocytes but also by other cell types. It plays a role in inflammatory processes, including the complement pathway, apoptosis, phagocytosis, and cytokine production. nCRP activates the classical complement pathway, induces phagocytosis, and promotes apoptosis, while mCRP promotes chemotaxis and delays apoptosis. nCRP and mCRP have opposing effects on nitric oxide (NO) production. mCRP increases pro-inflammatory cytokines like IL-8 and MCP-1, whereas nCRP has no detectable effect. CRP isoforms have distinct biological properties, with nCRP often exhibiting more anti-inflammatory activities. CRP is used as a marker of infection and cardiovascular events, but recent research highlights its role in inflammatory processes. CRP levels are influenced by factors such as age, gender, and hormone replacement therapy. Studies show that oral HRT increases CRP levels, while transdermal HRT may have less effect. CRP is involved in various diseases, including cardiovascular disease, infections, and atherosclerosis. It interacts with the complement system, influences apoptosis, and affects inflammatory responses. CRP also plays a role in the immune response to pathogens, including bacterial infections. The two isoforms of CRP have different functions, with nCRP and mCRP having opposing effects on inflammation and immune responses. Further research is needed to fully understand the roles of each CRP isoform in inflammatory and infectious processes.C-reactive protein (CRP) is an acute-phase inflammatory protein that increases up to 1,000-fold at sites of infection or inflammation. It is produced as a homopentameric protein, native CRP (nCRP), which can dissociate into monomeric CRP (mCRP) at sites of inflammation. CRP is synthesized primarily in liver hepatocytes but also by other cell types. It plays a role in inflammatory processes, including the complement pathway, apoptosis, phagocytosis, and cytokine production. nCRP activates the classical complement pathway, induces phagocytosis, and promotes apoptosis, while mCRP promotes chemotaxis and delays apoptosis. nCRP and mCRP have opposing effects on nitric oxide (NO) production. mCRP increases pro-inflammatory cytokines like IL-8 and MCP-1, whereas nCRP has no detectable effect. CRP isoforms have distinct biological properties, with nCRP often exhibiting more anti-inflammatory activities. CRP is used as a marker of infection and cardiovascular events, but recent research highlights its role in inflammatory processes. CRP levels are influenced by factors such as age, gender, and hormone replacement therapy. Studies show that oral HRT increases CRP levels, while transdermal HRT may have less effect. CRP is involved in various diseases, including cardiovascular disease, infections, and atherosclerosis. It interacts with the complement system, influences apoptosis, and affects inflammatory responses. CRP also plays a role in the immune response to pathogens, including bacterial infections. The two isoforms of CRP have different functions, with nCRP and mCRP having opposing effects on inflammation and immune responses. Further research is needed to fully understand the roles of each CRP isoform in inflammatory and infectious processes.