Obstructive sleep apnea does not affect circulating hematopoietic precursors.

Little is known on the effects of intermittent hypoxia on circulating hematopoietic precursors (CD34+ cells) in the obstructive sleep apnea syndrome (OSAS). We studied circulating CD34+ cells (myeloid precursors) and CD61+ cells (platelet precursors) by flow cytometry in controls (n=10; age: 44.1±4.9 yrs; BMI: 27.2±3.7 kg/m²) and in patients with untreated OSAS of variable severity (n=26, age: 49.1±6.2 yrs; BMI: 33.5±4.3 kg/m²; AHI: 56.7±29.9/h; SaO2 73.1±15.3%; time at SaO2<90%: 25.2±26.8%), after one night of CPAP treatment (n=13), and after prolonged CPAP treatment (n=7). Blood cell counts and plasma concentration of flt3-ligand, a hematopoietic growth factor, were also measured. The only difference between OSAS patients and control was a slight increase in CD34+ cell counts under no treatment in OSAS (10.3±12.0 vs. 5.0±2.8 cells/µL in controls, p<0.05 by Wilcoxon test). flt3-ligand concentration was similar in patients and controls (OSAS: 90±25; controls: 84±24 µg/mL), and increased with BMI in OSAS patients (r=0.46, p<0.05). No correlation was found between CD34+ cell counts and severity of OSAS, assessed as AHI, mean lowest SaO2 or time spent at SaO2<90%. Therefore, OSAS exerts small or no effect on circulating precursors.