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.
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.