PLATELET INHIBITORY EFFECTS OF CRP PREPARATIONS ARE DUE TO A CO-ISOLATING LOW-MOLECULAR WEIGHT FACTOR

  • 1 January 1982
    • journal article
    • research article
    • Vol. 45  (1) , 15-22
Abstract
C-reactive protein (CRP), an acute phase reactant, inhibits platelet activation through an effect upon a factor(s) critical to ADP-mediated secondary wave platelet aggregation but independent of a direct effect upon platelet contractile elements. A role for an accessory factor in this inhibitory effect became of concern because of an inconsistency in the effects of CRP preparations upon the platelet: inhibition was lost upon storage and CRP preparations differed, on a weight basis, in inhibitory capacity and sensitivity to the presence of the CRP ligand pneumococcal C-polysaccharide (CPS). Thus, studies were undertaken to assess whether an accessory factor was involved in the inhibition platelet activation observed with CRP. The activity of the inhibitory CRP preparations apparently resulted from association with a low MW factor (LMF) with an apparent nominal MW of 8300-12,500 and an absorption ratio (A280:A260) of .apprx. 0.4. Purified CRP did not inhibit platelet responsiveness but CRP with associated LMF (CRP-LMF) did. The inhibitory capacity of CRP-LMF but not LMF was substantially reversed in the presence of CPS. The platelet inhibitory properties of CRP preparations thus result from and are contingent upon the presence of a co-isolating LMF.