International archives of allergy and immunology
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Int. Arch. Allergy Immunol. · Oct 1996
Complement activation by C-reactive protein on the HEp-2 cell substrate.
The complement (C) activation by C-reactive protein (CRP) in acute-phase sera is routinely tested in our laboratory by means of an indirect immunofluorescence method (C3-IFT) on rat kidney sections. This C3-IFT assay is based on the binding of CRP to the renal tissue followed by the fixation of C4 and C3 components to distinct vessel-associated medullary structures as a result of CRP-mediated C activation in vitro. While the activation cascade leading to the deposition of C4 and C3 could previously be deduced experimentally, we were unable as yet to visualize CRP and the components of the C1 complex on kidney sections when testing patients' sera by indirect immunofluorescence. ⋯ HEp-2 cells can thus be used to monitor the process of autologous C activation initiated by endogeneous CRP in patients' sera. In contrast to native CRP, urea-modified CRP (mCRP) did not bind to HEp-2 cell nuclei, but was detected in association with distinct filamentous cytoplasmic structures. Unlike its native counterpart, binding of mCRP was not followed by a deposition of C components.