Induction of neuronal apoptosis by anti-Hu antibody. (A) Rat cerebellar slice culture incubated with anti-Hu serum for 72 hours and labeled with Cy5-conjugated donkey anti-human immunoglobulin (Ig)G (red), showing neuronal uptake of IgG. (B) Same culture showing fluorochrome-labeled inhibitors of caspases (FLICA) staining of neurons (blue), indicative of apoptosis. (C) Same culture stained with SYTOX dyes (green). There was extensive staining of neurons indicative of cell membrane destruction and death. (D) Merged image demonstrating that IgG-containing cells stained with both FLICA and SYTOX. Images are representative of studies employing anti-Hu sera from all seven patients, carried out in triplicate. Magnification bar = 20 μm.