Reduced CD43 expression on the neutrophils of MDS patients correlates withan activated phenotype of these cells

CD43 (also known as leukosialin and sialophorin) is a surface sialoglycopro tein expressed at high levels on most leukocytes implicated in adhesion, an tiadhesion, and activation/proliferation mechanisms. We studied the express ion of this molecule on the leukocytes of patients with myelodysplastic syn dromes (MDSs) in an effort to detect acquired deficiencies of this molecule . We used immunofluorescence flow cytometry in analyzing whole blood and is olated neutrophils from 49 MDS patients, 33 men and 16 women aged 33 to 85 years (median, 75 years), and 18 healthy individuals aged 35 to 80 years (m edian, 72 years). According to French-American-British classification crite ria, 13 patients had refractory anemia, 18 had refractory anemia with ringe d sideroblasts, 9 had refractory anemia with excess of blasts, 4 had refrac tory anemia with excess of blasts in transformation to acute leukemia, and 5 had chronic myelomonocytic leukemia. We found decreased expression of CD4 3 on the neutrophils of these patients, and we correlated this finding with the activation status of these cells as it is defined by their phenotypes. We studied the expression of CD11b, CD18, CD35, CD67, CD69, CD44, and CD53 molecules known to be changed in the activated form of neutrophils. CD43 e xpression correlated positively with CD53 and CD44 expression and negativel y with CD11b, CD18, CD35, CD67, and CD69 expression. Additionally, increase d levels of soluble vascular cell adhesion molecules were detected in these patients, suggesting endothelial cell activation. In conclusion, we believ e that the decreased expression of CD43 on the neutrophils of MDS patients is associated with activation of these cells and is probably due to cleavag e of the molecule from the cell surface and that the same mechanism is poss ibly responsible for the parallel down-regulation of CD44 and CD53. Int J H ematol. 2001;73:483-491. (C) 2001 The Japanese Society of Hematology.