Mannose Binding Lectin (MBL)

General Information

Mannose-binding lectin is an important glycoprotein of the immune system that binds to the carbohydrate group (mannose) on the membrane of a pathogen that has entered the body, thereby activating the complement system and providing the body's immune response.

Lectin is synthesized in the liver. The structure of lectin circulating in the blood is represented by an oligomer associated with a serine protease.

Studies confirm that mannose-binding lectin reacts with most non-encapsulated Gram-positive and Gram-negative bacteria, as well as viruses, fungi, mycobacteria, parasites, and unicellular microorganisms.

Upon recognition of the microbial carbohydrate component, the lectin undergoes a conformational change, which activates two serine proteases that are associated with it. Activation of the serine proteases in turn stimulates the cascade of immune responses through the lectin-mediated complement system. Activation of the complement system results in the destruction of target pathogenic microorganisms and their removal from the body by immune cells (granulocytes, monocytes, macrophages).

The lectin pathway of the complement system can also be activated by some antigen-antibody complexes, for example in patients with rheumatoid arthritis.

Mannose-binding lectin has also been shown to have antitumor cytotoxic effects. It is also found in the small intestinal epithelium and is thought to have a local protective effect.

When is the survey conducted?

The need for serum lectin determination arises when:

• During recurrent infections (in both adults and children)
• When complement system deficiency is suspected
• In immunodeficient patients
• In patients with unexplained immune dysfunction

Material for examination: Venous blood

Preparation of the patient: it is not necessary

Low levels of mannose-binding lectin in the blood are seen in bacterial and fungal (especially candida) infections. Prolonged viral infections (e.g., infections caused by herpes type 2) also show marked lectin deficiency.