MBL (Mannan-Binding Lectin) is a carbohydrate-binding protein produced in the liver and secreted into the blood. The protein plays a key factor in innate immunity, functioning as a player in the complement activation cascade and defending the body against invading microorganisms (bacteria, viruses, protozoa and fungi).
MBL exists at different levels of polymerization -- Non-functional and functional forms. A: a single chain monomer; B: 3 monomers joined in a collagen helix forming a subunit “flower; or C: up to 6 of “flowers” joined together to form a hexameric structure comprising a total of 18 MBL monomers.MBL deficiency is common and associated with increased susceptibility to infections. Due to the high genetic variation in the MBL gene, at least 12% of the average Caucasian population has insufficient levels of functional MBL. Diagnosing MBL-deficiency is possible, but unfortunately no direct treatment exists, and it is difficult to manage. MBL evaluations are relevant for many patient groups, including children with recurrent infections and adults with recurrent and severe infections. Other relevant patient groups include women who have experience recurrent spontaneous abortions; or immunocompromised patients undergoing cancer chemotherapy or immunosuppression (transplant), or those with an autoimmune disease. The main supportive therapeutics for these patients include regular antibiotics, antivirals and antifungals, but for patients with combined immunodeficiencies or recurrent spontaneous abortions, some doctors prefer IV immunoglobulin treatment.
