[Specific antibodies to iodinated contrast media. Research techniques, specificity]

Immuno-allergology of iodine contrast products is much discussed, the main questions posed by these molecules particularly concern the existence of specific IgE and their frequency, the specificity of the antibodies, involvement of the iodine atoms and their routes of sensitisation. Our preliminary study on 6 cases of urticaria (5) and erythema (1) after use of ioxaglate and with positive search for ioxaglate-specific IgE (2.3 to 6.7) after coupling to Sepharose (Baldo and Fisher technique). The results of this technique are expressed with reference to a pool of serum of subjects who had no contact with these contrast products. The threshold of positivity was 2, the mean of the results from 10 subjects who were exposed lay between 1.37 +/- 0.42. Inhibition of specific IgE by ioxaglate was positive in 6 cases. In 2/3 cases inhibition by potassium iodide was also observed. Several published studies in favour of the existence of specific IgE of close specificity, the inhibitions of specific IgE presented were mostly only observed for the contrast product used. An hypothesis would be that the ionic molecules have a greater capacity to induce the synthesis of specific IgE than non-ionic molecules because of their affinity for carrier proteins. The inhibitions seen with mineral iodine in this short study do not permit total elimination of the participation of the iodine atom at the antigenic site.