Affordable Access

Publisher Website

Polyethylene glycol enhances the binding of C1q to circulating immune complexes

Journal of Immunological Methods
Publication Date
DOI: 10.1016/0022-1759(81)90349-5


Abstract By radioimmunoassay we measured the amount of endogenous C1q that was precipitated by polyethylene glycol (PEG) under the conditions of the 125I-Clq-binding test (C1q-BT). We found a linear correlation between the percentage endogenous C1q that was precipitated and the 125I-C1q-binding activity )Clq-BA). We colcluded that the 125I-Clq behaves like the endogenous Clq. To detect circulating immune complexes (CIC) which had already bound C1q, human sera were added to tubes coated with anti-C1q. Under the conditioned used, no Clq-bearing CIC were detected. In addition, 7 sera from patients with high C1q-BA were analyzed by sucrose-gradient ultracentrifugation. No C1q was found in the fast sedimenting fractions, although Clq-BA was detected in these fractions. With IgG-coated tubes we observed that PEG enhanced the binding of 125I-C1q as well as endogenous C1q to aggregated and monomeric IgG. PEG also enhanced the binding of CIC to C1q-coated tubes. The results suggest that CIC detected by the C1q-BT do not bear C1q in significant amounts in the circulation and that these CIC become detectable only in the presence of PEG.

There are no comments yet on this publication. Be the first to share your thoughts.