90 Years On: A Therapy to ‘Stimulate the Phagocytes’?

The collectins (collagenous lectins) constitute a major element of the innate immune system and mannan‐binding lectin (or mannose‐binding lectin, MBL) is now recognized as a serum constituent with many of the attributes of both antibody and C1q. A common opsonic deficiency recognized more than 20 years ago is known to be a functional manifestation of MBL deficiency. This is largely explained by three single point mutations in exon 1 of the MBL gene, each of which disrupts the collagenous region and probably prevents assembly of higher order oligomers. Several independent studies suggest that deficiency of the protein increases significantly the risk of infection with a range of different pathogens and also predisposes such individuals to autoimmune disease. The first description of MBL replacement therapy [Valdimarsson et al ., Scand J Immunol 1998;48:116–123] provides evidence that administration of this purified plasma protein is safe, practical and possibly efficacious. These preliminary observations in two recipients now need to be extended in large‐scale trials.