ACTIVATION OF PLATELETS BY MODIFIED C-REACTIVE PROTEIN

  • 1 January 1982
    • journal article
    • research article
    • Vol. 45  (3) , 439-447
Abstract
The functional similarities between C-reactive protein (CRP) and Ig raised the possibility that modified CRP might resemble Ig in its activating effects upon the human platelet. Thermally-aggregated CRP (H-CRP), but not unmodified CRP, induced reactions of aggregation and secretion from isolated platelets; maximum response occurred with < 50 .mu.g/ml H-CRP and were similar to responses mediated by thermally-aggregated human IgG (AHGG). Platelet activation induced by H-CRP was sensitive to the presence of EDTA and dibucaine, required metabolic energy and was inhibited by increased levels of cAMP. Like AHGG, H-CRP acted synergistically with other platelet stimulators, although on a weight basis H-CRP appeared .apprx. 10- to 20-fold more effective than AHGG. Complexes formed between CRP and certain of its polycationic ligands (PLL [poly-L-lysine] and protamine) shared platelet activating properties with H-CRP, whereas complexes of CRP and CPS [pneumococcal C-polysaccharide] did not. The data point to the ability of appropriately modified CRP to stimulate or enhance platelet responsiveness. CRP can apparently initiate biological activities similar to those mediated by Ig.