Upregulation of Microparticles and CD40 Ligand in Antiphospholipid Syndrome: Potential Implication in Inflammatory Responses and Thrombosis.

Antiphospholipid syndrome (APS) represents a complex pathphysiologic state where vascular endothelium, platelet activation, coagulation and inflammatory processes are contributory to the overall outcome. Cellular apoptosis and immune mediated fragmentation results in the generation of microparticles (MP). Platelet associated CD40 Ligand contributes to the inflammatory complications, which may be further augmented by MP. To test the hypothesis that both the MP and CD40 ligand are increased in patients with APS, 90 samples received at Hines VA/Loyola Medical Center laboratories for antiphospholipid screening were profiled for MP utilizing a functional method and CD40 ligand employing an ELISA method (R&D, Minneapolis, MN). ProteinChip Array analysis was also carried out for biomarker profiling to identify a previously described inflammatory biomarker at 11.9 kDa utilizing surface enhanced laser desorption/ionization (SELDI). Fifty normal healthy male and female plasma samples were used as controls for comparative purposes. Of the 90 samples screened, 30 were found to be positive for the antiphospholipid antibody (APA) titer using an ELISA method (American Diagnostica, Stamford, CT). All of the 30 positive samples have elevated DRVVT; however, wide variations in the APTT were noted. The remainder of the 60 samples, which were negative for APA, also showed variability in the DRVVT and APTT values. In contrast, the DRVVT and APTT values in the normal were within the expected range. None of the normal samples were positive for the APA antibody. Most strikingly, the CD40 ligand in the samples positive for APA titer were markedly higher (480 ± 230 pg/ml) than the 60 which were negative (180 ± 80 pg/ml). The normal values were much lower (90 ± 30 pg/ml). The MP titer in the APA positive samples was also much higher (34 ± 14 nM) in contrast to the APA negative samples (18 ± 12 nM). The normal levels were even lower (9 ± 4 nM). In the ProteinChip Array analysis, the APA positive samples showed a higher prevalence of the unique biomarker at 11.9 kDa. This unique biomarker was absent in the normal human plasma. These findings clearly suggest that APA represents a complex syndrome where hemostatic activation involving the formation of the MP, upregulation of inflammatory process as evident by the generation of CD40 ligand and protease activation resulting in the formation of unique biomarkers contribute to its overall pathophysiologic outcome. Sequential profiling of these parameters may be helpful in the risk stratification of these patients.