ACTA1 and infection: Infection of the spleen is characterized by a breakdown of marginal zone architecture, loss of marginal zone macrophages (MZMs) and repositioning of marginal metallophilic macrophages (MMMs) (28), an increase in the number of red pulp macrophages (29), destruction of the follicular dendritic cell and the gp38+ fibroblastic reticular cell networks (13), and substantial changes to the vascular network, including sprouting of α-SMA+ vessels with active endothelial cell proliferation (30).