Compartmental analysis of short-lived platelet dynamics.
111In-labelled platelets were used for analysing platelet dynamics in 43 patients with idiopathic thrombocytopenic purpura (ITP). The detected time-activity curves, recorded with a gamma camera, were analysed by three methods: two- and three-compartment models, and an open model in which only the splenic curve was analysed. In the two-compartment model the mean rate constant from blood to spleen was 0.328 +/- 0.028 min-1 (mean +/- SEM) and from spleen to blood 0.061 +/- 0.007 min-1, whereas in the three-compartment model the corresponding values were 0.236 +/- 0.020 and 0.044 +/- 0.007 min-1, respectively. The mean rate constant from blood to liver was 0.466 +/- 0.149 min-1 and from liver to blood 0.341 +/- 0.106 min-1 as derived from the three-compartment model. The rate constant from spleen to blood, as determined from the three-compartment model, was significantly higher in patients with a strongly positive result for platelet-associated auto-antibodies (platelet suspension immunofluorescence test (PSIFT] than in patients with a negative PSIFT. The mean hepatic net rate in patients with a high level of antibodies is into the liver, while in patients with little or no antibodies the net rate is into the blood pool. The mean half-life for the fast component of the inverted splenic curve was 2.5 +/- 0.2 min and for the slow component 16 +/- 2 min. In patients with a strongly positive PSIFT the half-life for the slow component was significantly longer than in patients with a negative PSIFT.(ABSTRACT TRUNCATED AT 250 WORDS)
Savolainen
S
S
Department of Clinical Chemistry, Helsinki University Central Hospital, Finland.
Syrjälä
M T
MT
Liewendahl
K
K
Gripenberg
J
J
Nieminen
U
U
D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000032:analysis; D001792:Blood Platelets / Q000276:immunology / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D005455:Fluorescent Antibody Technique; D006207:Half-Life; D006801:Humans; D007205:Indium Radioisotopes; D008099:Liver / Q000166:cytology; D008875:Middle Aged; D008954:Models, Biological; D011696:Purpura, Thrombocytopenic / Q000097:blood*; D013154:Spleen / Q000166:cytology
D001323:Autoantibodies; D007205:Indium Radioisotopes