title: Appearance of a novel prostacyclin receptor antibody and duration of spinal cord injury.
abstract: BACKGROUND
  Cardiovascular disease (CVD) appears to be accelerated in individuals with chronic spinal cord injury (SCI). Previously, we have identified a novel circulating antibody (IgG) in persons with SCI that specifically blocks the high-affinity prostacyclin (PGI2) receptors on the platelet surface without affecting the low-affinity PGI2 receptors.
  
  
  OBJECTIVE
  In this study, the relationship between the time course after SCI to the development of IgG to the high-affinity PGI2 receptor was determined.
  
  
  METHODS
  Blood samples were collected 1, 3, 5, 10, and > 10 (15 +/- 4) years after SCI (n = 36). Plasma samples (50 microg) were analyzed by polyacrylamide gel electrophoresis (PAGE) followed by densitometry.
  
  
  RESULTS
  The optical density (OD) of the IgG (molecular weight 47,000) at 1 year after SCI was significantly higher than control (1.65 +/- 0.08 vs 1.33 +/- 0.04; P < 0.01). This anti-receptor IgG appears to increase for 5 years and then plateau. At 5 years, 6-10 years, and > 10 years of injury, the OD was 1.83 +/- 0.09, 1.83 +/- 0.10, and 1.87 +/- 0.08, respectively. With an increase in this specific IgG, there was a concomitant decrease in the binding of prostacyclin to its high-affinity receptors on SCI platelets, (non-SCI vs 1, 3, and 5 years after injury; n1 = 172 +/- 25 vs 153 +/- 15, 107 +/- 25, and 40 +/- 4 sites/platelet, respectively; P < 0.001), with no significant change in receptor affinity.
  
  
  CONCLUSIONS
  The level of the high-affinity PGI2-receptor antibody determined in individuals with SCI was associated with the duration and not with the level of injury. Platelets from subjects with SCI had a reduction in numbers of high-affinity receptors.
authors.affiliation: Department of Medicine, Mount Sinai School of Medicine, New York, New York, USA. nighat.kahn@med.va.gov
authors.forename: Nighat N
authors.initials: NN
authors.lastname: Kahn
authors.forename: William A
authors.initials: WA
authors.lastname: Bauman
authors.forename: Asru K
authors.initials: AK
authors.lastname: Sinha
mesh_terms: D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000503:physiopathology; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005500:Follow-Up Studies; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008875:Middle Aged; D010264:Paraplegia / Q000097:blood / Q000209:etiology; D011782:Quadriplegia / Q000097:blood / Q000209:etiology; D044006:Receptors, Epoprostenol / Q000097:blood*; D013119:Spinal Cord Injuries / Q000097:blood* / Q000150:complications; D013997:Time Factors
chemical_list: D007074:Immunoglobulin G; D044006:Receptors, Epoprostenol