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Cellular and Molecular Immunology logoLink to Cellular and Molecular Immunology
. 2008 Feb;5(1):9–21. doi: 10.1038/cmi.2008.2

The Classical and Regulatory Functions of C1q in Immunity and Autoimmunity

Jinhua Lu 1,*, Boon King Teh 1, Linda Wang 1, Yinan Wang 1, Yen Seah Tan 1, Min Chern Lai 1, Kenneth B M Reid 2
PMCID: PMC4652917  PMID: 18318990

Abstract

A classical function of C1q is to bind immune complexes and initiate complement activation producing membrane lytic complexes, opsonins and anaphylatoxins. This classical pathway of complement activation is also elicited when C1q binds some other ligands. Besides complement activation, C1q also regulates cell differentiation, adhesion, migration, activation and survival. C1q deficiency is associated with autoimmunity as well as increased susceptibility to infections. In this article, we discuss the basic properties of C1q, its expression, and classical and regulatory functions.

Keywords: C1q, macrophage, dendritic cell, apoptotic cell, autoimmunity

Glossary

DC

dendritic cell

SLE

systemic lupus erythematosus

MBL

mannan-binding lectin

AC

apoptotic cell

CRP

C-reactive protein

LPS

lipopolysaccharide

APC

antigen-presenting cell

CR

complement receptor


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