What does MBL stand for in immunology?

Mannose-binding lectin, abbreviated as MBL, is a crucial protein in the immune response. It belongs to a group of proteins known as collectins, which are involved in the recognition of specific carbohydrate patterns on pathogens. MBL plays an essential role in the innate immune system by binding to mannose and other sugar residues found on the surface of pathogens such as bacteria, viruses, and fungi.

Upon binding, MBL activates the complement system, which enhances opsonization—a process that marks pathogens for destruction by immune cells. This activation of the complement cascade also leads to the formation of membrane attack complexes that can directly lyse pathogens. Thus, MBL is vital for facilitating an initial immune response and helps in the clearance of infectious agents.

The other options do not accurately represent the function or nature of MBL in immunology: monoclonal binding ligand, main bacterial ligand, and molecular binding ligand are not established terms related to the immune system or MBL's role.