INFLAMMATORY POTENTIAL OF C-REACTIVE PROTEIN COMPLEXES COMPARED TO IMMUNE-COMPLEXES

C-reactive protein (CRP) is an acute phase serum protein that binds to phosphocholine (PC) and to components of damaged tissue. CRP resemble s antibody in that it binds to ligands and activates the classical com plement pathway. To compare the processing of CRP complexes to that of IgG complexes, we have prepared complexes containing the same ligand, PC-conjugated BSA, and IgG antibody to either BSA or CRP, We previous ly demonstrated similar complement-mediated binding of these complexes to erythrocyte complement receptors. CRP and IgG also bind to recepto rs on neutrophils (PMN), providing another possible pathway for cleara nce of ligands, PMN binding of IgG complexes can lead to activation wi th damaging inflammatory consequences. In the present report we have u sed CRP and IgG complexes containing PC-BSA to compare binding to PMN and activation of PMN adherence to endothelial cells. The results indi cate that CRP complexes do not activate PMN whereas IgG complexes do. Binding assays indicate that there is substantially greater binding of IgG than CRP complexes to PMN. (C) 1998 Academic Press.