Fluorescence confocal photomicrographs of double-labeling with plasma from a representative child with autism and antibodies directed toward calcium-binding proteins in area V1. (A to C) Immunoreactivity of (A) the autism (AU)-specific autoantibodies, (B) calbindin and (C) the merged image showing that several cells are colabeled (arrows), but that not all AU immunoglobulin G (IgG)-labeled cells express calbindin (arrowheads). Double-labeling with plasma from (D) a autoantibody-positive child with autism and (E) anti-parvalbumin shows that some AU IgG-labeled cells express parvalbumin (arrows), while most do not (arrowheads). (G to I) AU immunoreactivity (G) rarely occurs in cells that express calretinin (H) with no co-localization evident (I). Arrowheads point to cells that are labeled by the autoantibody, but not by anti-calretinin (I). Calibration bar, 100 μm.