Detection of plasma alpha-granule membrane protein GMP-140 using radiolabeled monoclonal antibodies in thrombotic diseases.

There is an assumption that platelet activation and endothelium damage play a critical role in the pathogenesis of thrombotic disorders. A radioimmunoassay based on using two monoclonal antibodies (MAbs) to different epitopes of alpha-granule membrane protein (GMP-140) was used to determine whether plasma GMP-140 can be detected in patients suffering from acute myocardial infarction (AMI) or cerebral thrombosis and in patients during cardiopulmonary bypass (CPB). MAb SZ-51 was used as a solid phase, and 125I-labeled MAb S12 was used as a fluid phase. The assay is so sensitive that it can detect as little as 1 ng/ml of purified GMP-140. The intra- and interassay coefficients of variation were 4.2% (n = 5) and 7.1% (n = 8), respectively. The concentration of plasma GMP-140 was found to be 10.0 +/- 4.5 ng/ml (mean +/- SD, n = 20) in normal subjects. Ten patients undergoing CPB demonstrated a transient increase in the concentration of plasma GMP-140, especially at 2 h after CPB, and the plasma GMP-140 level was inversely correlated with the decreased platelet counts during bypass (r = -0.81, p < 0.01). It was found that the concentration of plasma GMP-140 increased significantly after AMI. Plasma GMP-140 reached the peak within 3 days and changed with the process of AMI (n = 16) patients. The concentration of plasma GMP-140 increased significantly in patients with cerebral thrombosis in the acute phase but not after relief.(ABSTRACT TRUNCATED AT 250 WORDS)