title: Platelet splenic transit times in idiopathic thrombocytopenic purpura. Compartmental vs. non-compartmental model.
abstract: Platelet splenic transit times following injection of autologous or homologous 111In-labeled platelets were studied in 42 patients with idiopathic thrombocytopenic purpura. The transit times were determined by two methods from the splenic time-activity curves recorded with a gamma camera: closed two-compartmental model and non-compartmental model (deconvolution analysis). By compartmental analysis the mean splenic transit time for platelets was 6.3 +/- 0.3 min (mean +/- S.E.) and by non-compartmental analysis 7.6 +/- 0.4 min for all cases studied. The mean splenic transit time for autologous platelets was significantly (p less than 0.001) shorter (5.1 +/- 0.3 min) in patients with platelet-associated IgG (measured by platelet suspension immunofluorescence test) than in those with no autoantibodies (7.1 +/- 0.4 min), when the compartmental model was employed. There was no significant difference between mean transit times for autologous platelets in antibody positive and negative patients when deconvolution analysis was applied, but the residue of the splenic transfer function was lower for antibody positive than negative patients (7.2 +/- 1.0% vs. 11.7 +/- 1.6%, p less than 0.05). It is concluded that in idiopathic thrombocytopenic purpura the presence of platelet-associated autoantibodies expands the splenic platelet pool and reduces recirculation of platelets.
authors.affiliation: Department of Physics, University of Helsinki, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Savolainen
authors.forename: K
authors.initials: K
authors.lastname: Liewendahl
authors.forename: M T
authors.initials: MT
authors.lastname: Syrjälä
authors.forename: J
authors.initials: J
authors.lastname: Gripenberg
mesh_terms: D000293:Adolescent; D000368:Aged; D002648:Child; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000097:blood*; D012039:Regional Blood Flow; D013154:Spleen / Q000098:blood supply*