Updated project metadata. Both iron homeostasis and erythropoiesis are known to be affected by aging. Iron needs in mammals are met primarily by iron recycling from senescent red blood cells (RBCs), a task chiefly accomplished by red pulp macrophages (RPMs) in the spleen. Given that RPMs continuously process iron, their cellular functions might be susceptible to age-dependent decline, a possibility that has been unexplored to date. In our project, we identified a formation of undegradable iron- and heme-rich extracellular aggregates in the spleens of 10-11-month-old female mice. To better understand the origin of these aggregates, here, we performed: i) protein identification and intrasample quantification (iBAQ) of proteins of magnetically-isolated red pulp macrophages from spleens of two female 8-weeks-old C57BL/6J (maintained on a standard diet) and ii) label-free quantification of proteins of the splenic protein aggregates formed in the mouse spleen 24 hours after intraperitoneal iron dextran injection, using dextran-injected mice as a control. Two 8-week-old C57BL/6J mice per group were analyzed. This dataset is related to the project PXD032900, which describes quanytitative analysis of proteins in aggregates magnetically isolated from spleen of aged (standard or iron-reduced diet) and young mice (standard diet).