Quantitative, phenotypic, and functional evaluation of basophils in myelodysplastic syndromes

Background The myelodysplastic syndromes (MDS) are a group of clonal haemat ological disorders characterized by cytopenia(s), reduced differentiation-c apacity of myeloid cells, and impaired leukocyte function. However, little is known so far about basophil granulocytes in MDS. Design We have compared the numbers, phenotype and function of basophils in MDS patients with those in healthy subjects. A total numer of 23 patients with MDS (refractory anaemia, n = 8; refractory anaemia with ringsideroblas ts, n = 7; refractory anaemia with excess of blasts/refractory anaemia with excess of blasts in transformation, n = 8) and 20 healthy donors were incl uded. Results The numbers of blood basophils in MDS patients (34.6 +/- 62.9 muL(- 1)) was lower compared to healthy controls (58.6 +/- 64.9 muL(-1)). Corresp ondingly, whole blood histamine levels were lower in MDS patients (MDS 34.1 +/- 29.1 ng mL(-1) vs. normal donors 72.0 +/- 36.9 ng mL(-1)). Like 'norma l' basophils, basophils in MDS expressed interleukin-3 receptor alpha (CD12 3), E-NPP3 (CD203c), CR1 (CD35), CR3 (CD11b), CR4 (CD11c), membrane co-fact or protein (CD46), decay-accelerating factor (CD55) and membrane attack com plex inhibitory factor (CD59), as well as receptors for C3a, C5a (CD88), an d IgE. Recombinant human (rh) C5a and anti-IgE induced significant release of histamine from basophils in both groups of donors without significant di fferences between MDS and healthy controls. Conclusions The absolute numbers of basophils in MDS patients are lower tha n in normal donors. However, basophils in MDS do not differ from their 'nor mal counterparts' in terms of complement receptor expression, IgE-receptor expression, or functional responses to respective ligands.