Effect of iodinated contrast media on the synthesis and metabolism of leukotriene B₄

To investigate whether the endogenous vasoactive substrate, leukotriene B₄ (LTB₄), was induced in adverse reactions observed after intravenous injection of iodinated contrast media (CM), the authors measured the in vitro production and metabolism of LTB₄ by human polymorphonuclear leukocytes (PMNs) after stimulation with different doses of commercial CM preparations: iopamidol, 300 mg I/mL; iodamide, 300 mg I/mL; iohexol, 300 mg I/mL; ioxaglate, 320 mg I/mL; and the experimental preparation, iomeprolo. This study showed that the CM studied do not stimulate the production or metabolism of LTB₄ by isolated human blood PMNs. All of the CM studied except iodamide do not inhibit the production or metabolism of LTB₄ in PMNs stimulated by A23187. The in vitro hepatic microsomal oxidation of exogenous LTB₄ to (w-l)OH LTB₄ and w-OH LTB4 was inhibited by all the CM studied. LTB₄ production by PMNs seems not to play a major role in anaphylactoid reactions observed after iodinated CM. However, a transient blockade by CM of LTB₄ metabolism, leading to an increase of steady-state concentrations of LTB₄, could not be excluded by these experiments.