Aspect of anti-HMGCR autoantibodies in indirect immunofluorescence on HEp-2 cells. Classical indirect immunofluorescence assay using the HEp-2000™ line as cellular substrate. After incubation of serum at a 1/80 dilution, immunoreactivity was revealed by a FITC-labeled anti-human immunoglobulin (Ig)G secondary antibody. Example from two representative anti-HMGCR positive patients out of 20/33 sera with this immunofluorescence pattern shows a finely granular cytoplasmic staining with perinuclear reinforcement (left and middle). Inhibition by free HMGCR protein before immunofluorescence (right): the serum from example 2 was pre-incubated with free HMCGR before immunofluorescence assay. This yielded an extinction of immunoreactivity. HMGCR, 3-hydroxy-3-methylglutaryl coenzyme A reductase.