ICOS and atherosclerosis: As explained above, anti-ICOSL administration to mice did not have an effect on the development of atherosclerosis potentially because of off-target effects.9,46 BM transplantation from Icos–/– donors into Ldlr–/– recipients led to increased early atherosclerosis attributed to simultaneous loss of TREG numbers and function.70 Although TFH cells were not checked in this model, anti-OSE IgG1 and IgG3 were affected but IgM levels were unchanged.