sFLC

sFLC refers to soluble fragments of the complement cascade. The complement system is a critical part of the innate immune system, composed of a complex network of proteins that work together to identify and eliminate pathogens. When activated, these proteins undergo a series of cleavages, generating smaller, active fragments.

Some of these fragments, such as C3a, C5a, and C4a, are soluble and are released into the circulation. These sFLCs act as signaling molecules, playing diverse roles in inflammation and immunity. For instance, C3a and C5a are potent anaphylatoxins, capable of triggering mast cell degranulation, leading to increased vascular permeability and the recruitment of inflammatory cells. C5a also exhibits chemoattractant properties, drawing neutrophils and other phagocytes to sites of infection or injury.

The measurement of sFLCs in biological fluids like serum or plasma can provide valuable insights into the activation status of the complement system. Elevated levels of specific sFLCs are often indicative of underlying inflammatory or autoimmune conditions, such as systemic lupus erythematosus (SLE), rheumatoid arthritis, or sepsis. Consequently, sFLCs are utilized as biomarkers for diagnosing and monitoring disease activity, as well as for assessing the effectiveness of therapeutic interventions targeting the complement pathway. Their presence and levels can help differentiate between various inflammatory states and guide clinical decision-making.