MDSCs in the spleens of control patients and patients with ITP. CD11b⁺CD33⁺ double-positive cells in spleen sections were visualized by immunofluorescence. Nuclei were counterstained with DAPI. Representative staining of (Ai, Bi) nuclei, (Aii, Bii) CD33, (Aiii, Biii) CD11b, and (Aiv, Biv) merged images of control (A) and ITP (B) spleens. CD11b⁺CD33⁺ cells were counted per merged view. The expression (mean fluorescence intensity; OD = IOD/area) of iNOS in splenic MDSCs from control patients (Ci) and patients with ITP (Cii). Original magnification, ×400 (spleen). Scale bars, 20 μm.