Minchinton R M. Impact of mannose-binding lectin on susceptibility to infectious diseases

When the adaptive immune response is either immature or compromised, the innate immune system constitutes the principle defense against infection. Mannose-binding lectin (MBL) is a C-type serum lectin that plays a central role in the innate immune response. MBL binds microbial surface carbohydrates and mediates op-sonophagocytosis directly and by activation of the lectin complement pathway. A wide variety of clinical isolates of bacteria, fungi, viruses, and parasites are bound by MBL. Three polymorphisms in the structural gene MBL2) and 2 promoter gene polymorphisms are commonly found that result in production of low serum levels of MBL. Clinical studies have shown that MBL insufficiency is associated with bacterial infection in patients with neutropenia and meningococcal sepsis. Low MBL levels appear to predispose persons to HIV infection. Numerous other potential infectious disease associations have been described. Therapy to supplement low MBL levels is being explored using either plasma-derived or recombinant material. Five hundred fifty million years ago, key elements of the innate immune system, including mannose-binding lectin (MBL), were developing in early invertebrates, such as tunicates, sponges, and sea urchins [1]. In hu-mans, innate immune system recognition depends o