Effects of T-lymphocyte transplantation on iron homeostasis. Serum iron (mean ± 1 SD; A), duodenal ferroportin 1 (Fpn; B), and hepatic hepcidin (hamp; C) mRNA expression, on day 14 after T-cell infusion. Mice not injected with T lymphocytes served as controls. Mice were fed normal chow (normal Fe) or low Fe or high Fe diets. Values for panels B and C were obtained in each mouse by expressing the levels of Fpn1 and hamp, respectively, relative to the levels of β-actin; shown are the means plus or minus 1 SD of the relative values in 3 mice (normal Fe) or 5 mice (low and high Fe groups). (D) Fpn protein expression in the duodenum of mice on a high-iron diet. The top panel shows intense staining of enterocytes, most prominently in basolateral localization, in a mouse that underwent transplantation with allogeneic histoincompatible T cells; the bottom panel from a mouse that underwent transplantation with histocompatible (syngeneic) T cells shows only very faint staining for Fpn. Image for panel D created using Leica Dm 3000 (Wetzlar, Germany). The type, magnification, and numerical aperture of the objective lenses temperature are as follows: N plan dry 63×/0.80 NA, LED lighting. The imaging medium is as follows: digital camera photograph of paraffin-embedded, formalin-fixed glass slide, photos 64% (RGB/ 8; no fluorochromes). The camera make and model are as follows: Leica DCF 280 camera (Herrbrug, Switzerland). Acquisition software is as follows: Leica Microsystems, Leica Application Suite LAS 3.1.0 (build: 1983) CMS Adobe, Photoshop Elements 4 (San Jose, CA; 95 110-2704.)