[Qualitative and quantitative evaluation of CFU-E colonies in myelodysplastic syndromes]

Hemoglobin (Hb) synthesis in colony-forming-unit erythroid (CFU-E) colonies from the bone marrow of 10 normal subjects and 6 patients with myelodysplastic syndromes (MDS) was studied using microcytofluorometry. Hb content was determined utilizing a photochemical reaction in which the intracellular Hb is converted into fluorescent porphyrin. Briefly, the CFU-E in plasma clots was assayed according to Tepperman's method. Bone-marrow mononuclear cells were then dispensed onto petri dishes containing the plasma clots. The cells in plasma clots were cultured for seven days and then air-dried. The samples were then fixed with pure methanol. Thereafter, the dishes were exposed to ultraviolet light (lambda = 405 nm) in the presence of an SH-donor (0.2 M mercaptoethylamine hydrochloride). The intensity of porphyrin fluorescence was measured using a microcytofluorometer. When the photochemical reaction was carried out for 50 min, the intensity of fluorescence was found to be proportional to the mean corpuscular Hb (MCH) level, suggesting that the intracellular Hb level can be determined as a function of the intensity of this fluorescence. The number of CFU-E colonies in MDS patients was smaller than that in normal subjects. In addition, intracolony Hb level was markedly lower in the MDS cases than in normal subjects. Our findings suggest that the maturation process of CFU-E is impaired in MDS patients.