NEUTROPHILS FROM PATIENTS WITH MYELODYSPLASTIC SYNDROMES - RELATIONSHIP BETWEEN IMPAIRMENT OF GRANULAR CONTENTS, COMPLEMENT RECEPTORS, FUNCTIONAL ACTIVITIES AND DISEASE STATUS

Myelodysplastic syndromes (MDS) are stem cell disorders of clonal orig in in which infections and leukemic transformation are quite frequent. Neutrophils from 28 patients with MDS were analysed by flow cytometry for the expression of the two complement receptors CR1 and CR3, the a ntigenic reactivity of some granule constituents-myeloperoxidase, lyso zyme, elastase, lactoferrin-and functional activities, such as locomot ion, respiratory burst and cy totoxicity. The results were correlated with the FAB disease subtypes, grouped as low risk (RA) and high risk patients (RAEB, RAEB-t, CMML) and with 30 healthy subjects. A signific ant reduction in the percentage of neutrophil. CR1, CR3 positivity and chemotaxis induced by endotoxin-activated serum was detected in the h igh risk group when compared with the low risk group and healthy contr ols. Furthermore, the high risk group also showed a low amount of myel operoxidase, elastase, lysozyme and superoxide anion, but both low and high risk groups displayed reduced cellular cytotoxicity in compariso n with the control. This work indicates that MDS patients belonging to the more advanced FAB categories frequently show multiple abnormaliti es in the expression of neutrophil complement receptors, and granular components (>3), as well as in cell functions, suggesting the possibil ity of using these phenotypic abnormalities in the monitoring of disea se progression.