The complement system is a multi-functional system representing the first line host defense against pathogens in innate immune response, through three different pathways. Impairment of its function, consisting in deficiency or excessive deregulated activation, may lead to severe systemic infections or autoimmune disorders. These diseases may be inherited or acquired. Despite many diagnostic tools are currently available, ranging from traditional, such as hemolytic or ELISA based assays, to innovative ones, like next generation sequencing techniques, these diseases are often not recognized. As for therapeutic aspects, strategies based on the use of targeted drugs are now widespread. The aim of this review is to present an updated overview of complement system pathophysiology, clinical implications of its dysfunction and to summarize diagnostic and therapeutic approaches.
Keywords: Neisseria meningitidis; Angioedema; complement system; complement system deficiencies; paroxysmal nocturnal hemoglobinuria.