Legend. Active immunization with phosphorylcholine (PC) is protective against atherosclerosis. Extent of lesion development in the aortic root of ApoE ^-/-mice, immunized with phosphatebuffered saline (PBS), or adjuvant coupled to either keyhole limpet hemocyanin (KLH) immunostimulant carrier protein or PC-KLH. Representative micrographs of oil red-O–stained images. See page 542.