Figure 1

Intra-slide duplicate spot correlation. (A1) Nucleic acid programmable protein array (NAPPA) spotted with genes of interest. (A2) All proteins are tagged at the C-terminus to ensure only full-length translated proteins can be captured in situ by cospotted anti-tag antibodies. NAPPA has consistent protein amounts displayed at each spot; most are within twofold of the average [18, 19]. Proteins are expressed just in time for assay, which eliminates concern of protein stability. (B) The 768 antigen NAPPAs incubated with plasma (O1PL), synovial fluid (O1SF) and PBS (to control for detection antibody specificity). Arrays were rinsed and incubated with a fluorophore conjugated anti-human IgG detection antibody, to probe for antigen-bound antibodies originating from the sample. (C) Scatter plots of data that illustrate the correlation between duplicate protein antigen spots within the same slide. Correlation of all 768 antigen duplicates from a single patient for plasma (O1PL; r = 0.983) and synovial fluid (O1SF; r = 0.984) incubated slides. (D) Correlation values of intra-slide duplicate values for each patient sample (plasma and synovial fluid, n = 20) plotted to illustrate the precision of measurements across the experiment. An average correlation coefficient of r = 0.981 is observed across all samples (range of r = 0.971 to 0.988). {Figure 1D needed to be redrawn; please find new image for whole figure}