EFFECT OF RADIOGRAPHIC CONTRAST-MEDIA ON GRANULOCYTE PHAGOCYTOSIS OF ESCHERICHIA-COLI IN A WHOLE-BLOOD FLOW CYTOMETRIC ASSAY

RATIONALE AND OBJECTIVES. Earlier studies have demonstrated an adverse effect of radiographic contrast media (CM) on granulocyte phagocytosis. Most studies in the past have depended on granulocyte separative procedures that may themselves affect granulocyte functions. This study was performed to evaluate the effect of CM on phagocytosis using a flow cytometric assay allowing more physiological assay conditions. METHODS. Twenty consecutive patients were blindly randomized to receive the nonionic ratio 3.0 CM iohexol or the ionic ratio 3.0 CM ioxaglate for intravenous urography. Granulocyte phagocytic potential was measured before and at 1, 5, and 20 minutes after CM administration with a flow cytometric whole blood method evaluating the ingestion of complement- and immunoglobulin G (IgG)-opsonized fluorescent Escherichia Coli bacteria. RESULTS. The ability of granulocytes to phagocytize opsonized E. Coli was adversely affected by both CM used. Compared with baseline values, significantly decreased phagocytic activity was observed for iohexol at 1, 5, and 20 minutes and for ioxaglate at 1 and 5 minutes. The largest decrease with ioxaglate was from 85.3 +/- 10.5 to 69.3 +/- 16.3 (5 minutes), and the largest change with iohexol was from 87.1 +/- 8.5 to 74.5 +/- 15.9 (5 minutes). CONCLUSIONS. These results confirm earlier reports that ionic and nonionic CM adversely affect the phagocytic ability of granulocytes after intravenous administration.