Possible reasons for this include different research teams have various experimental designs, study methods, and focuses; cytokines produced by Th2 cells, especially IL-4, exhibit complex biological properties; most studies have been conducted in animal models, but animal models of atherosclerosis have certain limitations; and there are also complex interactions between immune cells, and Th2 may synergize with or antagonize other immune cells, thereby affecting its role in atherosclerosis. This evidence concerns the gene IL4 and atherosclerosis.