Tam A, et al. - Researchers performed this study with mice with COPD-like pathologies, to determine how female sex hormones can influence chronic cigarette smoke-induced expression of lymphoid aggregates in these participants. They used male, female, and ovariectomized mice exposed to air or cigarette smoke for 6 months, in whom, lymphoid aggregate counts, total aggregate cross-sectional area as well as foamy macrophage counts were evaluated morphometrically. In female mice vs male mice, lung tissues exhibited differentially increased lymphoid follicle and foamy macrophage counts as well as the total follicle cross-sectional area, and ovariectomy eliminated these differences. Overall, an increased risk of lymphoid aggregate formation correlated with chronic smoke exposure was identified in female mice vs male mice, which was mediated female sex hormones and B-cell activating factor expression in an oxidative environment.