The complement has been identified as a complementation factor to compensate a function of antibody. The complement consists of C1-C9, complement related molecules, and its regulating molecules. Three major biological roles in complement are classified. First is an opsonization following the phagocytosis and elimination of microbes. Second is a direct destruction of bacteria due to make membrane attack complex (MAC). Third is a complement activation following the induction of anaphylactoid factors and local recruitment and activation of neutrophilic leukocytes. In this review, I summarize the basic findings and recent treatments of paroxysmal nocturnal hemogloburinuria (PNH) and hereditary angioedema (HAE). Finally, I make a short review with a rare autosomal recessive disorder of 3MC syndrome and propose the new biological functions of complement factors except for that of innate immunity.
