C4b-binding protein (C4BP) activates B cells through the CD40 receptor

SR Brodeur, F Angelini, LB Bacharier, Anna Blom, E Mizoguchi, H Fujiwara, A Plebani, LD Notarangelo, Björn Dahlbäck, E Tsitsikov, RS Geha

Research output: Contribution to journalArticlepeer-review

103 Citations (SciVal)


We demonstrate that the a. chain of human C4b binding protein (C4BP) binds directly to CD40 on human B cells at a site that differs from that used by CD40 ligand. C4BP induces proliferation, upregulation of CD54 and CD86 expression, and IL4-dependent IgE isotype switching in normal B cells but not in B cells from patients with CD40 or IKKgamma/NEMO deficiencies. Furthermore, C4BP colocalized with B cells in the germinal centers of human tonsils. These observations suggest that C4BP is an activating ligand for CD40 and establish a novel interface between complement and B cell activation.
Original languageEnglish
Pages (from-to)837-848
Issue number6
Publication statusPublished - 2003

Subject classification (UKÄ)

  • Immunology in the medical area


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