Opsonisaatioon

Opsonisaatioon, which translates to opsonization in English, is a process in immunology that marks pathogens for ingestion and destruction by phagocytes. It is a crucial component of the innate immune system and also bridges the innate and adaptive immune responses. Opsonins are molecules that bind to the surface of microbes, such as bacteria and viruses, and also to the surface of phagocytes, acting like a bridge between the two.

The primary opsonins in the body are antibodies, particularly IgG, and complement proteins, such as C3b. Antibodies bind to specific antigens on the surface of the pathogen. Phagocytes have receptors that recognize the Fc region of these antibodies, facilitating the binding of the pathogen to the phagocyte. Complement proteins, part of the complement system, can coat the pathogen directly or be deposited onto the pathogen's surface through antibody binding. Phagocytes then recognize these complement proteins via complement receptors, leading to engulfment.

This enhanced phagocytosis, driven by opsonization, significantly increases the efficiency of pathogen clearance. Without opsonization, phagocytes would still attempt to engulf pathogens, but the process would be much slower and less effective. Opsonization essentially tags the "bad guys" for easier detection and removal by the immune system's "clean-up crew." This mechanism is vital for controlling infections and preventing the spread of disease.