TLR2 induces intracellular iron sequestration through a hepcidin-independent mechanism. (A) Ferritin mRNA transcription levels from PMA-differentiated THP-1 cells treated with TLR2 or TLR4 ligands for 24 hours quantified by qRT-PCR and normalized against untreated controls. GAPDH expression was used as a relative control. (B) THP-1 cells treated as in panel A and cell lysates were subjected to immunoblotting with the antiferritin (anti-FTH) antibody. (C) Densitometry analysis from western blot in panel B. (D) Prussian blue staining of PMA-differentiated THP-1 cells treated as described in panel A. Low magnification field (×10) is shown above, with high magnification (×40) shown below. All data were from 3 independent experiments. *P < .05.