Haematologica 2004;89: supplement no. 8 - Supplements ...

78Oral Communicationsmost frequent inherited thrombocytopenias wereMYH9-RD and BSS; c) some patients with the phenotypeof MYH9-RD or heterozygous BSS had nomutations in the genes for MYH9 or GPIb/IX/V,respectively, thus indicating genetic heterogeneityof these disorders.CO-111THERAPY WITH HIGH-DOSE DEXAMETHASONE (HD-DXM) INPREVIOUSLY UNTREATED PATIENTS AFFECTED BY IDIOPATHICTHROMBOCYTOPENIC PURPURAMazzucconi MG,* Bernasconi S,* Fazi P,*Amendola A,* De Rossi G,° Baronci C,° Leone G,^Carbone C,' Vianelli N,°° Quattrin S,** Fioritoni G,''Gugliotta L,^^ Mandelli F* for the GIMEMACooperative ITP Study Group*Dip. Biotec. Cellulari ed Ematologia Univ. "LaSapienza", Rom; °Divisione di Ematologia, OspedalePediatrico Bambino Gesù, Rome; ^Divisione diEmatologia, Università Cattolica del Sacro Cuore,Rome; 'Sezione di Ematologia e Trapianti, SpedaliCivili, Brescia; °° Istituto di Ematologia e OncologiaMedica L.e A. Seragnoli, Università di Bologna; **U.O.Oncoematologia Ospedale Santa Maria delleGrazie, Pozzuoli; ''Div. Emat. con Trapianto, AziendaUSL, Pescara, ^^ Servizio di Ematologia, Arcispedale"Santa Maria Nuova", Reggio Emilia, ItalyWe evaluated the efficacy, safety, feasibililty ofpulsed HD-DXM, as first-line therapy, in a series ofnewly diagnosed untreated ITP patients (pts).Patients with platelet (plt) count 30×10 9 /L or>30×10 9 /L with bleeding symptoms, were enrolled.HD-DXM was given at daily doses of 40 mg for 4days for four courses (on days: 0-14-28-42).Response was evaluated at day 60 from the treatmentonset: plt count 150×10 9 /L complete response(CR); 503030’) and defective in vitroplatelet aggregation to collagen were observed in thepropositus from family 1. Normal MPV, platelet aggregationand clot retraction were detected in family 2where only one member with mild bleeding tendencyhad prolonged bleeding time (11’). A reducedplatelet surface expression of GPIa-IIa was detectedby routine flow cytometry in all patients (32-50% ofcontrol). It is known that nucleotide polymorphysmsin the GPIa gene define multiple alleles associatedwith a different density of GPIa-IIa: allele 1(807T/837T/873A/Brb), allele 2 (807C/837T/ 873G/Brb)and allele 3 (807C/837C/873G/Bra) are associatedwith increased, low and intermediate levels of GPIa-IIa, respectively. Therefore, we typed these polymorphysmsin our patients and the results of subsequentanalyses were compared with genotype-matcheddonors. Defective expression levels of GPIa-IIa wereconfirmed both by flow cytometry and SDS-PAGE withimmunoblotting (30-60% of control). Platelet adhesionto monomeric collagen type I ranged from 15 to40% of that observed for controls. In family 1, residualadhesion to decorin was 40% while in family 2residual adhesion to the CB8 peptide, obtained fromdigestion of collagen II, ranged from 30 to 55% ofhaematologica vol. 89(suppl. n. 8):september 2004