The complement system in B cell regulation

Michael C Carroll1

  • 1Department of Pediatrics, The CBR Institute for Biomedical Research Inc., Harvard Medical School, 800 Huntington Ave., Boston, MA 02115, USA. caroll@cbr.med.harvard.edu

Early studies of animals bearing natural deficiencies in complement C3 and C4 and mice transiently deficient in C3 suggested that the complement system played a role in humoral immunity. Identification and characterization of the complement receptors CD21 and CD35 and their expression on B lymphocytes provided evidence for a direct role for complement in "linkage of innate and adaptive immunity". More recent studies of mice bearing targeted deficiencies in complement proteins C3, C4 or the receptors CD21/CD35 has confirmed the importance of complement in B cell responses in vivo and extended our understanding to distinct stages in B cell differentiation in which complement participates in humoral immunity. In this review, a role for complement is described in five distinct stages of B cell differentiation.

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