CD40LG and atherosclerosis: Indeed, as the major observed difference between genders, the reduced IgM in females seems to be critical to the outcome of atherosclerotic plaque development because female BtgApoe−/− had significantly enhanced atherosclerosis (Figure 5D) in contrast to the male counterparts (Figure 1) but similar to antibody-deficient Xbp1cKO mice27 and B cell (and therefore antibody)–deficient mice.35 The plaques of BtgApoe−/− female mice had larger necrotic cores (Figure VIB in the online-only Data Supplement).