Percentage of apoptotic cells in the BM erythroid cell compartments and BFU-E numbers in RA patients and healthy controls.

The left bars represent the mean percentage (± SE) of apoptotic cells detected by flow cytometry within the BM erythroid progenitor and precursor cell compartments in the total group of RA patients, the RA patients with ACD, the nonanemic RA patients, and the control subjects. The right bars represent the mean BFU-E colony values (± SE) obtained in the clonogenic assay by 10⁶ BMMCs in the above study groups. Comparison between patient and control values was performed by means of the nonparametric Mann-Whitney U test. *P < .05; **P < .01; ***P < .001.