Atypical hemolytic uremic syndrome: the role of complement pathway gene mutation analysis.

IW The complement system is a part of the innate immune system that is necessary for fighting infections and aberrant immunologic stimuli. Complement has 2 main functions. One function is opsonization: coating pathogens—such as bacteria, viruses, and dead cells— with C3b for macrophage clearance. The other function is cell lysis; that is, punching a hole in the membrane of a cell or pathogen. People who have a mutation in a complement regulatory protein do not have adequate capacity to limit complement activation. Some of the triggers for upregulation of complement activity are bacterial and viral infections, antigen-antibody complexes, autoimmunity, vaccination, pregnancy, and surgery. There may be a threshold for complement activation above which people who have some abnormality in their complement regulatory proteins become symptomatic. H&O Which mutations in complement alternative pathway genes are linked to aHUS?