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Abstract: Human serum amyloid P component (SAP) is of increasing interest for its possible pathogenic role in amyloidosis and Alzheimer''s disease, and as a therapeutic target in these conditions. We have developed and validated a robust and reproducible immunoradiometric assay (IRMA) for human SAP in serum, plasma and cerebrospinal fluid, and characterized the notable stability of human SAP immunoreactivity during storage of undiluted serum at 4°C and 37°C as well as frozen at −30°C. SAP values were also stable after repeated freeze thawing of highly diluted serum samples. The 100 fold dynamic range of the assay, 0.5–50μg/L, encompassed all values seen in blood and cerebrospinal fluid, when tested at suitable dilutions, from both normal healthy individuals and patients, including subjects receiving the SAP-depleting drug, CPHPC. Furthermore by comparing the IRMA values in the presence and absence of calcium, the new assay revealed interference due to the binding of CPHPC by SAP, which was markedly enhanced in heparinized plasma. It is therefore essential that SAP assays in samples from patients on CPHPC be conducted in the absence of free calcium, in order to completely abrogate interference and determine the actual total SAP concentration. Estimates by the IRMA of SAP concentration in 49 serum samples from amyloidosis patients corresponded closely with those obtained by the established standard electro-immunoassay method and by a newly developed commercial ELISA kit (Hycult Biotechnology). [Copyright &y& Elsevier]

Abstract: The pathogenic significance, if any, of the epidemiological association between baseline C-reactive protein (CRP) values and future atherothrombotic events is not known. We therefore investigated spontaneous atherosclerosis and atherothrombosis, and systemic markers of inflammation (acute phase proteins), in aged, normal diet-fed, male apolipoprotein E deficient (apoE−/−) mice with and without transgenic expression of human CRP. At 18 months of age, aortic atherosclerosis was extensive but with no significant difference in plaque size between C57BL/6apoE−/− mice with (apoE−/−-hCRP+) and without transgenic human CRP (apoE−/−). Atherosclerotic lesions in brachiocephalic arteries were typically complex and layered, with extensive fibrotic-cholesterol deposits, calcification and occasional recent intraplaque haemorrhage and thrombus, but with no significant overall differences between apoE−/− and apoE−/−-hCRP+ animals. Concentrations of mouse serum amyloid P component (SAP) were essentially normal throughout and did not differ between apoE−/− and apoE−/−-hCRP+ mice, or between wild-type (apoE+/+) and apoE−/− mice, regardless of human CRP expression. Mouse serum amyloid A protein (SAA), and human CRP concentrations were modestly but significantly higher in apoE−/−-hCRP+ than in apoE+/+-hCRP+ animals, but mouse SAA values were unaffected by transgenic expression of human CRP in either background. Thus, there was no evidence in this 18 month study of apoE−/−, and control apoE+/+ mice, that transgenic human CRP was pro-atherogenic, pro-inflammatory or pro-atherothrombotic. [Copyright &y& Elsevier]

Abstract: The human pentraxin proteins, serum amyloid P component (SAP) and C‐reactive protein (CRP) are important in routine clinical diagnosis, SAP for systemic amyloidosis and CRP for monitoring the non‐specific acute phase response. They are also targets for novel therapies currently in development but their roles in health and disease are controversial. Thus, both for clinical use and to rigorously elucidate their functions, structurally and functionally intact, pharmaceutical grade preparations of the natural, authentic proteins are required. We report here the production from normal human donor plasma and the characterization of the first such preparations. Importantly, we demonstrate that, contrary to reports using recombinant proteins and less well characterized preparations, neither CRP nor SAP stimulate the release by human peripheral blood mononuclear cells in vitro of any TNFα, IL‐6 or IL‐8, nor does SAP cause release of IL‐1β or IL‐10. Furthermore neither of our preparations was pro‐inflammatory in mice in vivo. [Copyright &y& Elsevier]