Complement: coming full circle

Abstract

The complement system has long been known to be a major element of innate immunity. Traditionally, it was regarded as the first line of defense against invading pathogens, leading to opsonization and phagocytosis or the direct lysis of microbes. However, from the second half of the twentieth century on, it became clear that complement is also intimately involved in the induction and "fine tuning" of adaptive B- and T-cell responses as well as lineage commitment. This growing recognition of the complement system's multifunctional role in immunity is consistent with the recent paradigm that complement is also necessary for the successful contraction of an adaptive immune response. This review aims at giving a condensed overview of complement's rise from a simple innate stop-and-go system to an essential and efficient participant in general immune homeostasis and acquired immunity.

Killing of CLL and NHL cells by rituximab and ofatumumab under limited availability of complement

“…Existence of several activation pathways and pattern-recognition molecules as well as multiple effector mechanisms including opsonisation, anaphylaxis and direct cell lysis ensure wide spectrum of direct and indirect cytocidal activities of complement [1]. Although tumor cells also display molecular patterns recognized by complement-activating molecules [2,3], numerous endogenous factors and mechanisms protect them from spontaneous complement attack [4].…”

Alzheimer’s Disease of the Immune System: A New Variant of Immune Deficiency

“…Other studies show altered immunoglobulin profiles (IgM, IgG subclasses, IgA) and decreased levels of regulatory T-cells in PANS patients compared to healthy controls [41,42]. At the 2013 PANS Consensus Conference, it was recommended that PANS patients undergo immunodeficiency assessments [43].…”

Chitosan based nanoparticles as protein carriers for efficient oral antigen delivery

“…Lysozymes can function as an innate opsonin to some extent or as a lytic enzyme [20].The complement system is a vital part of innate immune defense against foreign organisms and is responsible for various immune effecter functions including elimination of invading pathogens, promotion of inflammatory responses, in addition to modulation of adaptive immune response [3,21]. Lysozyme activity and complement activity in fish serum were detected by ELISA kit.…”