title: Persistent aggregates in apheresis platelet concentrates.
abstract: BACKGROUND
  Aggregates often appear during apheresis. Sometimes, these persist throughout storage, causing product wastage. This study assessed product quality of apheresis concentrates containing persistent aggregates (PA) and aimed to identify the factors that contribute to their formation.
  
  
  METHODS
  Donation (n = 180) and platelet indices (n ≥ 10) from apheresis concentrates with PA were compared with aggregate-free products.
  
  
  RESULTS
  The proportion of donors with at least one previous PA donation was twofold higher in the PA group (P < 0·0001) indicating a donor dependence. Significantly higher donor whole blood platelet counts (286 ± 50 vs. 266 ± 49 × 10(3) /μl, P < 0·0001) and higher apheresis yields (6·0 ± 1·6 vs. 5·4 ± 1·5 × 10(11) , P < 0·0001) were noted in the PA group. Haematocrit was also slightly higher, but age, gender and body mass were similar. The pH of PA products on day six postdonation was significantly lower (P < 0·001), in line with higher lactic acid concentrations. Flow cytometry showed no differences in GPIbα levels or phosphatidylserine exposure. However, there was slightly more integrin activation as well as increased degranulation measured by P-selectin expression. Cytokine concentrations were also significantly higher in PA concentrates. Aggregation was normal in response to SFLLRN peptide and collagen stimulation, but agglutination at low-dose ristocetin was significantly higher (P = 0.01) in PA products. Finally, PA were disintegrated by plasmin-mediated thrombolysis but not by integrin αIIb β3 inhibition.
  
  
  CONCLUSIONS
  Products with PA have acceptable quality parameters, but additional functional studies are warranted. Furthermore, PA are more likely to recur in certain donors who have higher platelet counts.
authors.affiliation: Transfusion Research Center, Belgian Red Cross-Flanders, Ghent, Belgium.
authors.forename: H B
authors.initials: HB
authors.lastname: Feys
authors.forename: J
authors.initials: J
authors.lastname: Coene
authors.forename: R
authors.initials: R
authors.lastname: Devloo
authors.forename: B
authors.initials: B
authors.lastname: Van Aelst
authors.forename: H
authors.initials: H
authors.lastname: Pottel
authors.forename: P
authors.initials: P
authors.lastname: Vandekerckhove
authors.forename: V
authors.initials: V
authors.lastname: Compernolle
mesh_terms: D000328:Adult; D001781:Blood Component Removal / Q000009:adverse effects*; D001792:Blood Platelets / Q000378:metabolism* / Q000502:physiology; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D019007:P-Selectin / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010718:Phosphatidylserines / Q000378:metabolism; D010974:Platelet Aggregation; D040201:Platelet Membrane Glycoprotein IIb / Q000378:metabolism
chemical_list: D019007:P-Selectin; D010446:Peptide Fragments; D010718:Phosphatidylserines; D040201:Platelet Membrane Glycoprotein IIb; C082835:thrombin receptor peptide (42-47); D019344:Lactic Acid
keywords: apheresis; blood collection; platelet concentrates