CD40 and pulmonary fibrosis: CD40 deficiency also significantly exacerbated TAC-induced pulmonary leukocyte infiltration (such as total CD45<sup>+</sup> cells, Mac2<sup>+</sup> cells and CD3<sup>+</sup> cells), ∼1.7-fold more pulmonary fibrosis, and pulmonary vessel remodeling, as well as the consequent right ventricular hypertrophy.