Myelodysplastic syndromes: a study of surface markers and in vitro growth patterns.

A study of surface markers and in vitro growth in semi-solid and liquid medium was performed in 35 patients with newly diagnosed myelodysplastic syndrome (MDS). Surface markers were studied by CD34, CD13, CD14, CD15, and CD33 monoclonal antibodies. There was no strict correlation with the FAB typing, but CD34 was expressed only in refractory anemia with excess of blasts (RAEB) or RAEB in transformation (RAEB-t). CD14 was markedly positive in the 4 cases of chronic myelomonocytic leukemia. Colony-forming cells were assessed by culture in semi-solid medium in the presence of HTB9 as growth factor. Four growth patterns were identified: a) normal growth (6 cases); b) no growth or low plating efficiency (10 cases); c) low colony and high cluster number (15 cases); and d) normal or high colony number with high number of clusters (4 cases). Expression of CD34 was associated with low colony and high cluster number. Finally we studied the proliferation and differentiation capacities in liquid culture without stimulating factor. Fifteen patients had a spontaneous proliferation. This was not correlated with any surface marker. Differentiation assessed by the loss of CD34 and/or the increase of CD15 by more than 20% at day 7 was observed in 21 cases. None of the surface markers or growth patterns was associated with a specific chromosomal abnormality, except the lack of growth in liquid culture observed in all 5q deletion cases. In univariate analysis, RAEB and RAEB-t FAB subtypes, percentage of blasts higher than 5%, staining by CD33 and CD34, and lack of differentiation in liquid culture were significantly associated with progression to leukemia and shorter survival. In multivariate analysis, only CD34 expression (P = .002) and percentage of blasts (P = .05) remained independent significant variables. CD34 was the only significant variable for prediction of survival (P = .05). It is concluded that surface marker analysis at diagnosis and after liquid culture may be a useful tool for the initial evaluation of MDS.