CD1 protein is overexpressed in trisomy 8. BMMNCs were stained with CD1-FITC and CD34-PE mAb and subjected to flow cytometry; CD34⁺ cells were gated, and the number of these cells staining with anti-CD1–FITC was quantitated. CD1 protein was increased in CD34 cells from patients with trisomy 8 compared with a group of healthy controls (A). CD1 expression was proportional to the number of trisomy 8 CD34 cells in the sample as determined by FISH using a specific chromosome 8 probe. (B) BMMNCs from patients with trisomy 8 were stained with CD34-PE and CD1-FITC. Cells were sorted into CD34⁺, CD1⁺, and CD1⁻ aliquots by flow cytometry; FISH for chromosome 8 was performed on the sorted samples. There were increased trisomy 8 cells in the CD1⁺ fraction. (C) Immunoblots were performed on nuclear extracts of BMMNCs for c-myc. Increases in patients with trisomy 8 compared with healthy controls (n = 2) or other patients with MDS (n = 6) were seen. Error bars represent SEM.