Sublytic mice are iron deficient. (A) Serum iron levels (n = 5 for wild-type mice and n = 3 for sublytic mice, P = .0357). (B) Liver iron stores (n = 4 for wild-type mice and n = 5 for sublytic mice, P = .0159). (C) Sections of spleens from sublytic and wild-type mice stained for iron with Prussian blue and shown at a 20× magnification. (D) Hamp expression measured by quantitative RT-PCR using total RNA isolated from liver. Expression was normalized to that of endogenous S18 transcripts (n = 5 for wild-type mice and n = 3 for sublytic mice, P = .0357). (E) Gastrointestinal iron absorption. Mice were maintained on a regular diet or on an iron-deficient diet for 1 month. Animals were fasted for 12 hours before gastric instillation of ⁵⁹FeCl₃. Iron absorption was determined 24 hours after gastric feeding (n = 6 for wild-type mice and n = 5 for sublytic mice). The percentage of absorption was calculated as the amount of radioactivity in the whole animal minus the gastrointestinal tract, divided by the amount instilled by gavage. Note that wild-type mice were rendered anemic, as determined by complete blood count analysis, by feeding with the iron-deficient diet for 1 month. Graphical data are expressed as means ± SEM. *P < .05.