Frequencies of aRibPR0, aRibPR1 and aRibPR2 in aRibPNH-negative lupus patients. (a) Results according to specificity of 99% are shown in a Venn diagram. (b) Corresponding to Figure 2a, those sera were selected that were exclusively positive for aRibPR0, aRibPR1 or aRibPR2 among aRibPNH-negative SLE patients. To further show exact and comparable signal intensities, fold change indices in relation to the given cutoffs of each recombinant aRibP protein (see also Table 1) were calculated. ARibPNH, antibodies against native ribosomal P heterocomplex; aRibPR0, antibodies against recombinant ribosomal P0 protein; aRibPR1, antibodies against recombinant ribosomal P1 protein; aRibPR2, antibodies against recombinant ribosomal P2 protein; aRibPs, anti-ribosomal P protein antibodies.