Among them, both EGF and IL-6 concentrations had a median increase of 3–4 fold, respectively. On the MK0683 mouse other hand, some proteins are not known to be secreted by blood cells.

For example, VCAM-1 is expressed in endothelial cells (Osborn et al., 1989), both SAA (Uhlar and Whitehead, 1999) and CRP (Pepys and Hirschfield, 2003) are produced predominantly by the liver. All three proteins remained stable to the traditional sample handling. As the pre-analytical sample handling has an impact on non-antibody protein concentrations, it would stand to reason that it may also impact the results of a multi-biomarker disease activity algorithm. The MBDA scores from samples that were obtained by different pre-analytical sample types and sample handling variables were evaluated. The use of plasma, as compared to serum, significantly impacted a large number of subjects’ MBDA score, with changes from + 18 to − 8 MBDA units (Fig. 2A).

The MBDA score obtained from serum handled by the traditional method also resulted in significant changes, − 8 to + 24 MBDA units (Fig. 2B), relative to the protocol method. With both pre-analytical variables, the magnitude of the change of MBDA scores was inversely correlated with the MBDA scores measured with serum samples. Autoantibody biomarker measurements appear robust to blood collection and handling methods. In contrast, blood collection, NVP-BEZ235 order processing and handling methods had a significant impact on measurable serum protein concentrations. Plasma samples generally exhibited decreased levels for the protein biomarkers assayed. The results of this study illustrate the importance of characterizing pre-analytical variability to ensure test accuracy for development, validation, and clinical testing with biomarker assays. This is especially critical when these assays are integrated in large clinical trials, where using standardized serum processing and handling procedures would be an essential part of the study design, directly affecting results interpretation and next phase of trials. This work was funded by Crescendo Bioscience. Xiaoyan Zhao, Ferhan Qureshi, P. Scott Eastman, William

Neratinib mw C. Manning, Claire Alexander and Lyndal K. Hesterberg are employees of Crescendo Bioscience. Crescendo Bioscience owns patents relating to the MBDA test. Patent applications that include William H. Robinson have been filed by Stanford University for the use of autoantibody biomarkers in rheumatoid arthritis, and royalties have been received for these patents. In addition, licensing agreements between Stanford University and Crescendo Bioscience regarding the use of autoantibody biomarkers have been established. The authors would like to acknowledge the Oklahoma Arthritis Center and the McBride Clinic Orthopedic and Arthritis Center for sample collection; Wayne Hu, Melanie West, Nicholas Santana and Igor Vainshtein for excellent technical assistance; and Linda J. Kahl for editorial assistance.