title: Role of C-reactive protein in complement-mediated hemolysis in Malaria.
abstract: Human C-reactive protein (CRP) is a clinically important classical acute phase protein. Although CRP has been reported to bind with many nucleated cells, the direct binding of CRP to erythrocytes in diseases remains largely unexplored. The main focus of the present study was to investigate the binding of disease-specific CRP to erythrocytes of same patients. Distinct molecular variant of disease-specific CRP was affinity purified from sera of malaria patients (CRP(Mal)). This CRP showed strong binding with malaria erythrocytes (RBC(Mal)) as confirmed by flow cytometric analysis (FACS), enzyme-linked immunosorbent assays (ELISA), and radio binding assays. Calcium and phosphoryl choline (PC) were found to be essential for this interaction. A 2.3-fold increased binding of induced CRP to RBC(Mal) as compared to normal erythrocytes (RBC(N)) confirmed disease-specificity. Preincubation of RBC(Mal) with unconjugated CRP showed 3-5 fold inhibition. The association constant of CRP and RBC(Mal) was 4.7 x 10(6) cpm/microg with the corresponding number of receptors/cell being 4.3 x 10(5). The effector function of CRP(Mal) has been demonstrated by its potency to activate the complement pathway. An optimal dose of 10 microg/ml of CRP induced three-fold higher hemolysis of patient erythrocytes as compared to RBC(N). These studies provide direct evidence for an important phagocytic functional interaction of this acute-phase protein by triggering the CRP-complement pathway after the binding of CRP(Mal) with RBC(Mal). Hemolysis as triggered by this pathway may be one of the causative factors of anemia, a common clinical manifestation of this disease.
authors.affiliation: Immunobiology Division, Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata, 700 032, India.
authors.forename: Waliza
authors.initials: W
authors.lastname: Ansar
authors.forename: Sumi Mukhopadhyay Nee
authors.initials: SM
authors.lastname: Bandyopadhyay
authors.forename: Suchandra
authors.initials: S
authors.lastname: Chowdhury
authors.forename: Sk Hasan
authors.initials: SH
authors.lastname: Habib
authors.forename: Chitra
authors.initials: C
authors.lastname: Mandal
mesh_terms: D002097:C-Reactive Protein / Q000302:isolation & purification / Q000378:metabolism*; D016022:Case-Control Studies; D002478:Cells, Cultured; D003165:Complement System Proteins / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006461:Hemolysis / Q000502:physiology*; D006801:Humans; D008288:Malaria / Q000097:blood*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism
chemical_list: C071581:CRP protein, human; D008565:Membrane Proteins; D011971:Receptors, Immunologic; D003165:Complement System Proteins; D002097:C-Reactive Protein