What does 'CR' in CR1 stand for?

The 'CR' in CR1 stands for 'Complement Receptor.' CR1 is a protein that plays a critical role in the immune system, particularly in the complement pathway. It is found on the surface of various immune cells, including B cells, monocytes, and macrophages. This receptor binds to complement components, specifically C3b, which is important for opsonization and clearance of pathogens and cellular debris.

The presence of CR1 on immune cells enhances their ability to recognize and respond to pathogens coated with complement. This process is essential for promoting phagocytosis and facilitating communication between different components of the immune system. Thus, the term 'Complement Receptor' accurately reflects its function in mediating interactions related to the immune response.