Therefore, close follow-up and staining of subsequent biopsies should be performed. Likewise, a focal staining pattern is frequently observed during the resolution of AMR episode ( Figure 17.8e and f). Focal C4d staining of greater than 10% up to 50% of capillaries is considered negative for reporting purposes but it may represent an evolving AMR. The intensity (faint or strong) and semiquantitative assessment of staining distribution (focal, multifocal or diffuse) should be reported. Positivity is specified by staining of greater than 50% of interstitial capillaries ( Figures 17.7c–f and 17.8a–d). Regardless of IF or IHC, the diagnostic staining patterns of C4d and C3d are the same. Table 46.8 summarizes the clinical significance of serum complement in SLE. A combination of these tests appears to be one of the most promising useful biomarkers for lupus disease activity.
#C4d live serial#
Prospective studies to determine whether serial measurements of CB-CAPs combined with anti-C1q, anti-dsDNA, and serum C3 and C4 can predict disease flares are needed. 102 Wallace and colleagues 103 found that the combined panel of CB-CAPs and autoantibodies can help distinguish primary fibromyalgia, especially in those with positive ANA from SLE.ĭespite its limitations, measurement of native C3 and C4 levels has not been replaced by CB-CAPs in current clinical practice. A large multicenter study of CB-CAPs combined with a panel of autoantibodies to cellular and to citrullinated antigens reported a higher sensitivity and diagnostic specificity for SLE compared with anti-dsDNA and hypocomplementemia. 98ĬB-CAPs may be helpful in the diagnosis of SLE. 98-101 A prospective study of active SLE with elevated CB-CAPs at baseline found that a reduction of E-C4d, E-C3d, and the serum titer of C1q at follow-up was significantly associated with clinical improvement using validated measures of disease activity. 97 Cross-sectional and longitudinal studies have found that measurement of these cell-bound complement activation products (CB-CAPs) is useful in monitoring disease activity. Quismorio, in Dubois' Lupus Erythematosus and Related Syndromes (Ninth Edition), 2019 Cell-Bound Complement Activation ProductsĬ4d and C3d bind covalently to erythrocytes (E-C4d, E-C3d), to B lymphocytes (B-C4d), and to reticulocytes (R-C4d) to form a stable long-lived cell-bound marker that can be quantified by flow cytometry.
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