OpsoninRezeptoren

Opsoninrezeptoren are a class of cell surface receptors that play a crucial role in the innate immune system's ability to recognize and eliminate pathogens and other foreign particles. These receptors bind to opsonins, which are molecules that coat the surface of a target, marking it for destruction by phagocytic cells such as macrophages and neutrophils. This process is known as opsonization.

Common examples of opsonins include antibodies (specifically IgG), complement proteins (such as C3b), and C-reactive protein. When an antibody binds to a pathogen, its Fc region becomes accessible. Opsoninrezeptoren on phagocytes, like Fc receptors, can then bind to this Fc region, initiating phagocytosis. Similarly, complement receptors can bind to complement proteins that have deposited on the pathogen's surface, also triggering engulfment.

The binding of opsonins to their respective receptors on phagocytes leads to the activation of signaling pathways within the phagocyte. This activation enhances phagocytosis, promotes the intracellular killing of the engulfed particle through the release of reactive oxygen species and lysosomal enzymes, and can also stimulate the release of cytokines, which further modulate the immune response.

In essence, opsoninrezeptoren act as bridges, connecting the humoral immune system (through antibodies and complement) to the cellular immune system (through phagocytes). This facilitates a more efficient and targeted clearance of unwelcome substances, contributing significantly to host defense against infection and disease. Dysfunction of opsoninrezeptoren can impair immune responses, making individuals more susceptible to infections.