Figure 10. Accumulation of labile iron and regulation of FPN1 in blood monocytes in iron overload diseases.

(A and B) Blood samples (FPN: whole-blood leukocytes, calcein: PBMCs) were obtained from healthy controls (n = 18) and myelodysplastic syndrome (MDS) patients with or without hyperferritinemia (FT^lo: serum ferritin <400 ng/ml, n = 7 and FT^hi: serum ferritin <400 ng/ml, n = 5). Surface FPN1 expression (A) and calcein fluorescence (B) in monocyte subpopulations were determined by flow cytometry. Monocyte subpopulations were defined as described in Supplemental Figure 10AB (red: classical; gray: intermediate; blue: nonclassical monocytes). Calcein MFI is assumed to be inversely proportional to LIP levels. Representative signal FPN1 and calcein histograms are shown (tinted histograms: specific staining, open histograms: isotype). Graphs show ΔMFI and MFI values. Each point represents 1 measurement, bars denote mean, and error bars represent SEM. Statistical significance for the healthy vs. MDS FT^lo and MDS FT^lo vs. MDS FT^hi comparisons were determined with first-order linear models. Separate models were applied to each monocyte subset. Estimate values with 95% CI are shown. Estimate P values were calculated with 2-tailed t test. ANOVA statistics are presented in Supplemental Table 6.