Granulocyte Adherence after Intravenous and Intraarterial Injection of Ioxaglate or Iohexol

The effect of iohexol and ioxaglate on granulocyte adherence to nylon fibers was investigated with blood from 15 patients undergoing angiography, and from 24 patients undergoing excretory urography. Decreased adherence and increased numbers of granulocytes in the circulation were observed soon after injection of iohexol or ioxaglate in the aorta, or injection of ioxaglate i.v. Increased adherence and decreased numbers of granulocytes in the circulation were observed soon after injection of iohexol i.v. The differences were small soon after the injection of contrast media (CM). More pronounced decreased adherence and increased numbers of granulocytes were detected 2 and 5 hours after injection in the aorta for both CM.

Granulocyte Adherence is Inhibited by Radiographic Contrast Media in Vitro

Different amounts of diatrizoate, ioxaglate, iohexol, iodixanol, NaCl 1000 mOsm/kg, mannitol 1098 mOsm/kg, and meglumine (meglumine concentrations corresponding to the content in the diatrizoate solutions) were added to either whole blood or a suspension of granulocytes in autologous plasma, and the adherence to nylon fibers was determined. At high concentrations all the investigated contrast media (CM) inhibited granulocyte adherence. The degree of inhibition was significantly greater when the ionic CM diatrizoate and ioxaglate were used, as compared with the nonionic media. Meglumine solutions at high concentrations also inhibited adherence but significantly less than diatrizoate solutions containing the same amount of meglumine. Diatrizoate showed the greatest inhibitory effect on granulocyte adherence, and significant inhibition could be detected even with a 1.25% solution.

Granulocyte Chemotaxis

One of the important functions of granulocytes is the ability to respond to a chemoattractive signal by migration. The influence of radiographic contrast media (CM) on the chemoattractive properties of serum was investigated by under agarose technique for chemotaxis. No chemotactic response was seen when serum was incubated with different concentrations of CM after heat inactivation. The CM did not generate the heat stable complement split product C5a-desarg which would have resulted in a chemotactic response. Without heat inactivation all complement available in the serum was activated by the agarose in the chemotaxis assay. Low concentrations of iohexol and iodixanol brought about an increased chemotactic response relative to a reference with saline instead of CM. This may be due to activation of heat labile chemoattractants from other sources than the complement cascade. At high concentrations of all five investigated CM, a decreased number of granulocytes migrated over a shorter distance when compared with the reference, and this may be due to interactions between the CM and chemoattractants or their precursors.

Granulocyte Chemotaxis before and after Urography

Granulocytes isolated from whole blood of 10 volunteers with Hypaque/Ficoll or Percoll gradient centrifugation showed a significant inhibition of their chemotactic response when incubated with diatrizoate. The influence of 4 different i.v. injected radiographic contrast media (CM) on granulocyte chemotaxis was evaluated using the under agarose assay. Each CM was injected in 10 consecutive outpatients referred for urography. Cells and serum were obtained before and 20 min after the injection of CM. Autologous serum was used as chemoattractive agent, and the cell suspensions from both samples were tested against serum drawn both before and after the injection of CM. No significant changes in granulocyte chemotaxis or the chemotactic potential of serum were seen. Furthermore, there was no change in the chemotactic response towards homologous serum or N-fmlp after injection of diatrizoate or iohexol. In conclusion, the investigation did not unveil any change in granulocyte chemotaxis 20 min after the injection of CM in the 40 subjects studied.

Phagocytic Properties of Granulocytes after Intravenous Injection of Ioxaglate or Iohexol

To evaluate the influence of radiographic contrast media (CM) on human granulocytes, the ability of these cells to ingest latex particles after intravenous injection of ioxaglate and iohexol was investigated. Both CM inhibited the phagocytic properties of granulocytes; the inhibition was the most pronounced immediately after the injection, but inhibition was also observed 60 min after injection of ioxaglate. The inhibition 1 and 5 min after injection of CM was more pronounced after injection of ioxaglate than after injection of iohexol. However, this difference between the 2 CM was not significant. Significant inhibition of phagocytosis was found for mannitol solutions with osmolalities higher than 369 mOsm/***1. Significant inhibition of phagocytosis was observed when granulocytes were isolated with either Hypaque/Ficoll or Percoll gradient centrifugation and then incubated with diatrizoate. Thus the ability of granulocytes to phagocytize latex particles was inhibited after i.v. injection of 50 ml ioxaglate or iohexol. Part of this inhibition may be due to hyperosmolality.

Comparison of two classes of non-peptide drugs as antagonists of neutrophil receptors for f-Met-Leu-Phe. Pyrazolons and iodinated radiographic contrast agents

The radiographic contrast agent sodium diatrizoate (DTR) reportedly inhibits f-Met-Leu-Phe-induced chemotaxis in human neutrophils. DTR is also an ingredient of Ficoll-Paque, a density centrifugation medium widely used to purify human polymorphonuclear leukocytes (PMNs). Exposure of PMNs to DTR during preparation had no detrimental effect on subsequent binding characteristics of tritiated f-Met-Leu-Phe, probably owing to a rapid dissociation of DTR from the PMN receptors. DTR competed directly with f-Met-Leu-Phe for receptor binding, but was 160- and 640-fold less potent than phenylbutazone and 1,2-diphenyl-4-[3-(1-naphthyl)-propyl]-3,5-pyrazolidinedione (DPN; an analog of phenylbutazone), respectively. Iohexol and the methylamide of DTR did not compete with [3H]f-Met-Leu-Phe in receptor binding, supporting the existence of a definite interaction between iodinated aromatic molecules and the f-Met-Leu-Phe receptor. DTR did not inhibit prostaglandin synthesis, as did DPN. Both drugs inhibited chemotactic peptide-induced release of superoxide anion in a concentration-dependent manner, and were relatively selective for f-Met-Leu-Phe, as opposed to C5a. Both drugs at 10 microM interfered non-selectively with chemotactic peptide-induced beta-glucuronidase release from PMNs. Available non-peptide antagonists of f-Met-Leu-Phe exhibited other pharmacodynamic properties that could make them unsuitable for future in vivo studies designed to probe the physiological role of the receptor.