What receptor binds to C3b?

C3b is a component of the complement system and plays a crucial role in opsonization, which enhances the ability of antibodies and phagocytic cells to clear pathogens. The receptor that specifically binds to C3b is CR1. This receptor, also known as complement receptor 1, is expressed on a variety of immune cells, including macrophages and B cells.

When C3b binds to CR1 on these cells, it facilitates the phagocytosis of pathogens that have been opsonized with C3b, or it may help in the lysis of pathogens through the activation of the complement cascade. The action of CR1 not only aids in pathogen clearance but also plays a role in regulating complement activation, preventing excessive inflammation and tissue damage.

In contrast, other receptors mentioned, such as CR2, CR3, and CD19, serve different functions. While CR2 binds to iC3b (a cleaved form of C3b) and is important for B cell activation, CR3 interacts with other components in the immune response and has a role in binding to different ligands, including other complement fragments. CD19 is primarily a co-receptor for B cell activation and does not have a direct role