COMPLEMENT RECEPTOR-TYPE-1 (CR-1) DEFICIENCY ON NEUTROPHILS IN MYELODYSPLASTIC-SYNDROME

We present a patient with myelodysplastic syndromes (MDS) whose neutro phils exhibited defective expression of complement receptor type 1 (CR 1). A 73-year-old man was admitted with an evolution of MDS from RA in to RAEBT according to the FAB classification of MDS. The neutrophil al kaline phosphatase (NAP) score was zero. The surface expression of mem brane effector molecules on neutrophils was determined by indirect imm unofluorescence using now cytometry and monoclonal antibodies. The exp ression of CR1 on neutrophils as identified by staining with CD35 was defective in the patient, and the expression of other complement recep tors (CR3 and CR4), Fc receptors and adhesion molecules was normal. CR 1 deficiency and defective NAP score on neutrophils in the patient mig ht account for impairment of common storage pool, presumably novel int racellular secretory vesicles.