Development of a quantitative assay for the detection of anti-HMGCR antibodies. (A) SDS-PAGE analysis of the recombinant HMGCR catalytic C-domain after Coomassie blue staining. (B) Western blot analysis of this recombinant HMGCR using a specific rabbit anti-HMGCR antibody or a human anti-HMGCR-positive serum. (C) Addressable laser bead immunoassay (ALBIA-HMGCR) using serial dilutions of rabbit anti-HMGCR antibody. The mean fluorescence intensity (MFI) values are the mean of triplicate determinations. Standard deviation (SD) errors bars are not visible because of very low variability (coefficients of variation SD/mean lower than 1%, range (0.0025 to 0.7525)). Insert, higher magnification for the low anti-HMGCR antibody concentrations (horizontal dotted line depicts mean + 2 SD of 20 negative controls). HMGCR, 3-hydroxy-3-methylglutaryl coenzyme A reductase.