APOE and atherosclerosis: Apoe–/– mice crossed with mice lacking the V(D)J recombination-activating protein 1 Rag1 (Rag1–/–) or mice with a severe combined immunodeficiency (SCID) mutation (scid/scid mice) are immunodeficient owing to impaired T-cell and B-cell development and showed reduced atherosclerosis lesions when fed a chow diet (220).