[Activation of the complement system and cytokine production by radiographic contrast media in vascular endothelial cells in vitro].

The direct effect of four different radiographic contrast media (RCM) on the release of C3a and C5a and the production of IL-1 alpha and TNF-alpha from vascular endothelial cells was examined in vitro. The test RCM were as follows: diatrizoate (ionic monomer), iopamidol (nonionic monomer), ioxaglate (ionic dimer), and iotrolan (nonionic dimer). These were added to serum-free medium and adjusted to a final concentration of 1% (2.8 mg Iodine/ml). Human microvascular endothelial cells were stimulated by serum-free medium containing the test RCM for eight hours. After incubation, the media were aspirated and assayed for the concentrations of C3a, C5a, IL-1 alpha and TNF-alpha. Finally, the cells were harvested by trypsin, and their viability was determined by the dye-exclusion method. Diatrizoate and iotrolan had higher C3a release than the control (p < 0.05). No increase in C5a, IL-1 alpha or TNF-alpha levels was observed with any of the tested RCM, and there was no significant difference in cell viability with any of the tested RCM. The results of this study suggest that diatrizoate and iotrolan activated the complement system through the alternative pathway by directly stimulating vascular endothelial cells. These observations suggest that a direct effect of RCM on vascular endothelium might play a role in the pathogenesis of local drug eruptions due to RCM.