Retinal pigment epithelium and microglia express the CD5 antigen-like protein, a novel autoantigen in age-related macular degeneration

Sera of subjects with age-related macular degeneration exhibit auto-antibodies directed against an antigen that, following 2D gel and mass spectrometry experiments, was discovered to be the CD5-like (CD5L) protein, a secreted scavenger receptor known to be produced by macrophages. Immunohistochemical experiments reveal that this antigen is expressed also throughout the cytoplasm and, more discretely, at the nuclear level (inset) by human retinal pigment epithelium cell lines. Confocal immunohistochemical microscopy experiments show also that CD5L reactivity in human macular neuroretinal tissue section colocalizes with reactivity for Iba1, a known microglial specific marker.449