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 (lgG) in persons with SCI that specifically blocks the high-affinity prostacyclin (PGI) receptors on the platelet surface without affecting the low-affinity PGI 2 receptors.Objective: In this study, the relationship between the time course after SCI to the development of lgG to the high-affinity PGI 2 receptor was determined.Methods: Blood samples were collected 1, 3, 5, 10, and > 1 0 (15 ±4) years after SCI (n = 36). Plasma samples (50 11g) were analyzed by polyacrylamide gel electrophoresis (PAGE)followed by ensitometry.Results: The optical density (OD) of the lgG (molecular weight 47,000) at 1 year afterSCI was significantly higher than control (1 .65 ±0.08 vs 1.33 ±0.04; P < 0.01 ). Thisanti-receptor lgG 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 ±0.1 0, and 1.87 ±0.08, respectively. With an increase in this specific lgG, there was a concomitant decrease in the binding of prostacyclin to its high-affinity receptors on SCIplatelets, (non-SCI vs 1, 3, and5years after injury; n1 = 1 72 ±25 vs 153 ±15, 1 07 ±25, and 40 ±4 sites/platelet, respectively; P < 0.001 ), with no significant change inreceptor 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. Plateletsfrom subjects with SCI had a reduction in numbers of high-affinity receptors.